Earth science

@misc{chamberlin1904the1,
    author = "Chamberlin, T. C",
    title = "The methods of the earth-science",
    year = "1904",
    howpublished = "Popular Science Monthly, v. 66, p. 66-75",
    note = "talkorigins\_source = {true}; raw\_reference = {Chamberlin, T. C., 1904, The methods of the earth-science: Popular Science Monthly, v. 66, p. 66-75.}"
}

I. Introductory. Of all regions of the earth none invites speculation more than that which lies beneath our feet, and in none is speculation more dangerous; yet, apart from speculation, it is little that we can say regarding the constitution of the interior of the earth. We know, with sufficient accuracy for most purposes, its size and shape: we know that its mean density is about 5 1/2 times that of water, that the density must increase towards the centre, and that the temperature must be high, but beyond these facts little can be said to be known. Many theories of the earth have been propounded at different times: the central substance of the earth has been supposed to be fiery, fluid, solid, and gaseous in turn, till geologists have turned in despair from the subject, and become inclined to confine their attention to the outermost crust of the earth, leaving its centre as a playground for mathematicians. The object of this paper is not to introduce another speculation, but to point out that the subject is, at least partly, removed from the realm of speculation into that of knowledge by the instrument of research which the modern seismograph has placed in our hands. Just as the spectroscope opened up a new astronomy by enabling the astronomer to determine some of the constituents of which distant stars are composed, so the seismograph, recording the unfelt motion of distant earthquakes, enables us to see into the earth and

@article{doi101144gsljgs1906062010421,
    author = "Oldham, Richard Dixon",
    title = "The Constitution of the Interior of the Earth, as Revealed by Earthquakes",
    year = "1906",
    journal = "Quarterly Journal of the Geological Society",
    abstract = "I. Introductory. Of all regions of the earth none invites speculation more than that which lies beneath our feet, and in none is speculation more dangerous; yet, apart from speculation, it is little that we can say regarding the constitution of the interior of the earth. We know, with sufficient accuracy for most purposes, its size and shape: we know that its mean density is about 5 1/2 times that of water, that the density must increase towards the centre, and that the temperature must be high, but beyond these facts little can be said to be known. Many theories of the earth have been propounded at different times: the central substance of the earth has been supposed to be fiery, fluid, solid, and gaseous in turn, till geologists have turned in despair from the subject, and become inclined to confine their attention to the outermost crust of the earth, leaving its centre as a playground for mathematicians. The object of this paper is not to introduce another speculation, but to point out that the subject is, at least partly, removed from the realm of speculation into that of knowledge by the instrument of research which the modern seismograph has placed in our hands. Just as the spectroscope opened up a new astronomy by enabling the astronomer to determine some of the constituents of which distant stars are composed, so the seismograph, recording the unfelt motion of distant earthquakes, enables us to see into the earth and",
    url = "https://doi.org/10.1144/gsl.jgs.1906.062.01-04.21",
    doi = "10.1144/gsl.jgs.1906.062.01-04.21",
    openalex = "W1980688227"
}

The observed variation of the seismic velocities with depth, below the crust, is examined with reference to the variation to be expected in a homogeneous medium. A general equation is derived for the variation of the quantity,, in a homogeneous gravitating layer with an arbitrary gradient of temperature. The parameters of this equation are then discussed in terms of the experimental and theoretical relations for solids. The principal parameter is (∂KT/∂P)T, the rate of change of isothermal incompressibility with pressure, which can be found for large compressions from Bridgman's measurements. Comparison of observed and expected rates of variation of ϕ throughout the Earth's interior leads to conclusions regarding homogeneity and, with a larger uncertainty, to estimates of temperature. A shadow zone at a depth of about 100 km, as suggested by Gutenberg, may be accounted for by a gradient of temperature of about 6°/km in a homogeneous layer of ultrabasic rock. Between depths of about 900 and 2,900 km, the mantle appears to be substantially uniform, and at a relatively uniform temperature of the order of several thousand degrees. Between about 200 and 900 km, the rate of rise of velocity is too great for a homogeneous layer, and indicates a gradual change of composition, or of phase, or both. New phases are required to account for the high elasticity of the deeper part of the mantle (below 900 km), and it is suggested that, beginning at about 200 to 300 km, there is a gradual shift toward high-pressure modifications of the ferro-magnesian silicates, probably close-packed oxides, with the transition complete at about 800 to 900 km. There may also be a concentration of alumina, lime, and alkalis toward the upper part of the mantle, in and above the transitional layer but below the crust, existing in minerals of high elasticity such as garnets and jadeites. The transitional layer appears to hold the key to a number of major geophysical problems. The velocities in the core and inner core are also reviewed. The inner core is most simply interpreted as crystalline iron, the outer part as liquid iron, perhaps alloyed with a small fraction of lighter elements. The density and compressibility of iron at high pressures are estimated with the aid of the experimental compressions of the alkali metals; the central density is found to be about 15. Several other recent proposals regarding the crust are discussed.

@article{doi101029jz057i002p00227,
    author = "Birch, Francis",
    title = "Elasticity and constitution of the Earth's interior",
    year = "1952",
    journal = "Journal of Geophysical Research Atmospheres",
    abstract = "The observed variation of the seismic velocities with depth, below the crust, is examined with reference to the variation to be expected in a homogeneous medium. A general equation is derived for the variation of the quantity,, in a homogeneous gravitating layer with an arbitrary gradient of temperature. The parameters of this equation are then discussed in terms of the experimental and theoretical relations for solids. The principal parameter is (∂KT/∂P)T, the rate of change of isothermal incompressibility with pressure, which can be found for large compressions from Bridgman's measurements. Comparison of observed and expected rates of variation of ϕ throughout the Earth's interior leads to conclusions regarding homogeneity and, with a larger uncertainty, to estimates of temperature. A shadow zone at a depth of about 100 km, as suggested by Gutenberg, may be accounted for by a gradient of temperature of about 6°/km in a homogeneous layer of ultrabasic rock. Between depths of about 900 and 2,900 km, the mantle appears to be substantially uniform, and at a relatively uniform temperature of the order of several thousand degrees. Between about 200 and 900 km, the rate of rise of velocity is too great for a homogeneous layer, and indicates a gradual change of composition, or of phase, or both. New phases are required to account for the high elasticity of the deeper part of the mantle (below 900 km), and it is suggested that, beginning at about 200 to 300 km, there is a gradual shift toward high-pressure modifications of the ferro-magnesian silicates, probably close-packed oxides, with the transition complete at about 800 to 900 km. There may also be a concentration of alumina, lime, and alkalis toward the upper part of the mantle, in and above the transitional layer but below the crust, existing in minerals of high elasticity such as garnets and jadeites. The transitional layer appears to hold the key to a number of major geophysical problems. The velocities in the core and inner core are also reviewed. The inner core is most simply interpreted as crystalline iron, the outer part as liquid iron, perhaps alloyed with a small fraction of lighter elements. The density and compressibility of iron at high pressures are estimated with the aid of the experimental compressions of the alkali metals; the central density is found to be about 15. Several other recent proposals regarding the crust are discussed.",
    url = "https://doi.org/10.1029/jz057i002p00227",
    doi = "10.1029/jz057i002p00227",
    openalex = "W2087983709"
}

@article{doi1010160032063363901132,
    author = "Runcorn, S. K.",
    title = "Earth Science and meteoritics",
    year = "1963",
    journal = "Planetary and Space Science",
    url = "https://doi.org/10.1016/0032-0633(63)90113-2",
    doi = "10.1016/0032-0633(63)90113-2",
    openalex = "W232118281"
}

@article{doi1010160016003266902705,
    author = "Knopoff, L.",
    title = "Advances in earth science",
    year = "1966",
    journal = "Journal of the Franklin Institute",
    url = "https://doi.org/10.1016/0016-0032(66)90270-5",
    doi = "10.1016/0016-0032(66)90270-5",
    openalex = "W251429503"
}

@article{bennett1969physical,
    author = "Bennett, Clifford",
    title = "Physical science: Bedrock of the earth sciences",
    year = "1969",
    journal = "Science Education",
    url = "https://doi.org/10.1002/sce.3730530209",
    doi = "10.1002/sce.3730530209",
    number = "2",
    openalex = "W2003739053",
    pages = "125-126",
    volume = "53"
}

@article{doi1010160012821x69901836,
    author = "Turekian, Karl K. and Clark, Sydney P.",
    title = "Inhomogeneous accumulation of the earth from the primitive solar nebula",
    year = "1969",
    journal = "Earth and Planetary Science Letters",
    url = "https://doi.org/10.1016/0012-821x(69)90183-6",
    doi = "10.1016/0012-821x(69)90183-6",
    openalex = "W2036773053"
}

It follows from the analysis of observation data that the secular variation of the mean temperature of the Earth can be explained by the variation of short-wave radiation, arriving at the surface of the Earth. In connection with this, the influence of long-term changes of radiation, caused by variations of atmospheric transparency on the ther-mal regime is being studied. Taking into account the influence of changes of planetary albedo of the Earth under the development of glaciations on the thermal regime, it is found that comparatively small variations of atmospheric transparency could be suffi-cient for the development of quaternary glaciations. As paleogeographical research including ma-terials on paleotemperature analyses has shown (Bowen, 1966, et al), the Earth's climate has long differed from the present one. During the last two hundred million years the temperature difference between the poles and equator has been comparatively small and there were no zones of cold climate on the Earth. By the end of the Tertiary period the temperature at tem-perate and high latitudes had decreased ap-preciably, and in the Quaternary time subse-quent increase in the thermal contrast between the poles and equator took place, that waa fol-lowed by the development of ice cover on the land and o c e m a t temperate and high latitudes. The size of Quaternary glaciations changed several times, the present epoch correspbnding to the moment of a decrease in the area of gla-ciations that still occupy a considerable part of the Earth's surface. To answer the question of in what way the climate will change in future, it is necessary to establish the causes of Quaternary glaciations initiation and to determine the direction of their development. Numerous studies on this problem contain various and often contradic-tory hypotheses on the causes of glaciations. The absence of the generally accepted view-point as regards this seems to be explained by the fact that the existing hypotheses were based mainly on qualitative consideratiow allowing different interpretation. Tellus XXI (1969), 6

@article{doi101111j215334901969tb00466x,
    author = "Budyko, M. I.",
    title = "The effect of solar radiation variations on the climate of the Earth",
    year = "1969",
    journal = "Tellus",
    abstract = "It follows from the analysis of observation data that the secular variation of the mean temperature of the Earth can be explained by the variation of short-wave radiation, arriving at the surface of the Earth. In connection with this, the influence of long-term changes of radiation, caused by variations of atmospheric transparency on the ther-mal regime is being studied. Taking into account the influence of changes of planetary albedo of the Earth under the development of glaciations on the thermal regime, it is found that comparatively small variations of atmospheric transparency could be suffi-cient for the development of quaternary glaciations. As paleogeographical research including ma-terials on paleotemperature analyses has shown (Bowen, 1966, et al), the Earth\'s climate has long differed from the present one. During the last two hundred million years the temperature difference between the poles and equator has been comparatively small and there were no zones of cold climate on the Earth. By the end of the Tertiary period the temperature at tem-perate and high latitudes had decreased ap-preciably, and in the Quaternary time subse-quent increase in the thermal contrast between the poles and equator took place, that waa fol-lowed by the development of ice cover on the land and o c e m a t temperate and high latitudes. The size of Quaternary glaciations changed several times, the present epoch correspbnding to the moment of a decrease in the area of gla-ciations that still occupy a considerable part of the Earth\'s surface. To answer the question of in what way the climate will change in future, it is necessary to establish the causes of Quaternary glaciations initiation and to determine the direction of their development. Numerous studies on this problem contain various and often contradic-tory hypotheses on the causes of glaciations. The absence of the generally accepted view-point as regards this seems to be explained by the fact that the existing hypotheses were based mainly on qualitative consideratiow allowing different interpretation. Tellus XXI (1969), 6",
    url = "https://doi.org/10.1111/j.2153-3490.1969.tb00466.x",
    doi = "10.1111/j.2153-3490.1969.tb00466.x",
    openalex = "W2118222708",
    references = "doi1011751520046919670240241teotaw20co2"
}

@misc{strahler1971the4,
    author = "Strahler, A. N",
    title = "The Earth Sciences [2nd ed.]",
    year = "1971",
    howpublished = "New York, Harper \& Row, 824 p",
    note = "talkorigins\_source = {true}; raw\_reference = {Strahler, A. N., 1971, The Earth Sciences [2nd ed.]: New York, Harper \& Row, 824 p.}"
}

@article{beckinsale1972the,
    author = "Beckinsale, Robert P. and Runcorn, Stanley Keith",
    title = "The Royal Institution Library of Science. Earth Sciences",
    year = "1972",
    journal = "The Geographical Journal",
    url = "https://doi.org/10.2307/1795982",
    doi = "10.2307/1795982",
    number = "2",
    openalex = "W2315631865",
    pages = "245",
    volume = "138"
}

@book{hallam1973a3,
    author = "Hallam, A",
    title = "A Revolution in the Earth Sciences",
    year = "1973",
    publisher = "New York, Oxford University Press",
    note = "talkorigins\_source = {true}; raw\_reference = {Hallam, A., 1973, A Revolution in the Earth Sciences: New York, Oxford University Press.}"
}

@article{doi1010160012821x7590223x,
    author = "Cumming, G. L. and Richards, John R.",
    title = "Ore lead isotope ratios in a continuously changing earth",
    year = "1975",
    journal = "Earth and Planetary Science Letters",
    url = "https://doi.org/10.1016/0012-821x(75)90223-x",
    doi = "10.1016/0012-821x(75)90223-x",
    openalex = "W2114276383",
    references = "doi1010160016003266902705"
}

In 1896 when Emil Wiechert proposed his model of the Earth with an iron core and stony shell, scientists generally believed that the entire earth was a solid as rigid as steel. R. D. Oldham’s identification of P and S waves in seismological records allowed him to detect a discontinuity corresponding to a boundary between core and shell (mantle) in 1906, and Beno Gutenberg established the depth of this boundary as 2900 km. But failure to detect propagation of S waves through the core was not sufficient evidence to persuade seismologists that it is fluid (contrary to modern textbook statements). Not until 1926 did Harold Jeffreys refute the arguments for solidity and establish that the core is liquid. In 1936 Inge Lehmann discovered the small inner core. K. E. Bullen argued, on the basis of plausible assumptions about compressibility and density, that the inner core is solid. Attempts to find seismic signals that have passed through the inner core as S waves have so far failed (with one possible exception), but analysis of free oscillations provided fairly convincing evidence for its solidity.

@article{doi101119112026,
    author = "Brush, Stephen G.",
    title = "Discovery of the Earth’s core",
    year = "1980",
    journal = "American Journal of Physics",
    abstract = "In 1896 when Emil Wiechert proposed his model of the Earth with an iron core and stony shell, scientists generally believed that the entire earth was a solid as rigid as steel. R. D. Oldham’s identification of P and S waves in seismological records allowed him to detect a discontinuity corresponding to a boundary between core and shell (mantle) in 1906, and Beno Gutenberg established the depth of this boundary as 2900 km. But failure to detect propagation of S waves through the core was not sufficient evidence to persuade seismologists that it is fluid (contrary to modern textbook statements). Not until 1926 did Harold Jeffreys refute the arguments for solidity and establish that the core is liquid. In 1936 Inge Lehmann discovered the small inner core. K. E. Bullen argued, on the basis of plausible assumptions about compressibility and density, that the inner core is solid. Attempts to find seismic signals that have passed through the inner core as S waves have so far failed (with one possible exception), but analysis of free oscillations provided fairly convincing evidence for its solidity.",
    url = "https://doi.org/10.1119/1.12026",
    doi = "10.1119/1.12026",
    openalex = "W2061082812"
}

We suggest that the partial pressure of carbon dioxide in the atmosphere is buffered, over geological time scales, by a negative feedback mechanism in which the rate of weathering of silicate minerals (followed by deposition of carbonate minerals) depends on surface temperature, and surface temperature, in turn, depends on carbon dioxide partial pressure through the greenhouse effect. Although the quantitative details of this mechanism are speculative, it appears able partially to stabilize earth's surface temperature against the steady increase of solar luminosity believed to have occurred since the origin of the solar system.

@article{doi101029jc086ic10p09776,
    author = "Walker, James C. G. and Hays, P. B. and Kasting, James F.",
    title = "A negative feedback mechanism for the long‐term stabilization of Earth's surface temperature",
    year = "1981",
    journal = "Journal of Geophysical Research Atmospheres",
    abstract = "We suggest that the partial pressure of carbon dioxide in the atmosphere is buffered, over geological time scales, by a negative feedback mechanism in which the rate of weathering of silicate minerals (followed by deposition of carbonate minerals) depends on surface temperature, and surface temperature, in turn, depends on carbon dioxide partial pressure through the greenhouse effect. Although the quantitative details of this mechanism are speculative, it appears able partially to stabilize earth's surface temperature against the steady increase of solar luminosity believed to have occurred since the origin of the solar system.",
    url = "https://doi.org/10.1029/jc086ic10p09776",
    doi = "10.1029/jc086ic10p09776",
    openalex = "W2097828895",
    references = "doi1010160016703772901196, doi1010160016703779900590, doi101016b0080437516071036, doi101029jc085ic10p05529, doi101038277640a0, doi101126science177404352, doi1011751520045019690080392agcmbo20co2, doi1011751520046919750322033toebcm20co2, doi1011751520046919750322044teocts20co2, openalexw1564144063"
}

The history of ideas about the earth's core is reviewed, from the l9th century to the present. Following the determination of the outer core boundary by B. Gutenberg and the establishment of the fluidity of the core by H. Jeffreys, the current model for the overall physical structure was completed by Inge Lehmann's discovery of the inner core and the proposal by F. Birch and K.E. Bullen that the inner core is solid > The traditional assumption that the core is primarily iron was challenged by several scientists in the 1940's, especially W.H. Ramsey, who proposed that the core boundary marks a change in physical but not chemical state. His hypothesis, that the core is a liquid ‘metallized silicate,’ was refuted by research on the properties of silicates at high pressures, but it raised the question whether a theory of the present state of the earth's interior should be consistent with some plausible theory of its origin and development. While Western geophysicists tended to ignore this criterion, a group of Russian scientists developed a theory which satisfied it, although it was difficult to maintain the metallized silicate hypothesis. A compromise model, proposed in the 1970s, involves iron and oxygen in proportions chosen to satisfy density conditions but also derivable by physicochemical evolution from an initially homogeneous earth.

@article{doi101029eo063i047p01185,
    author = "Brush, Stephen G.",
    title = "Chemical history of the Earth's core",
    year = "1982",
    journal = "Eos",
    abstract = "The history of ideas about the earth's core is reviewed, from the l9th century to the present. Following the determination of the outer core boundary by B. Gutenberg and the establishment of the fluidity of the core by H. Jeffreys, the current model for the overall physical structure was completed by Inge Lehmann's discovery of the inner core and the proposal by F. Birch and K.E. Bullen that the inner core is solid > The traditional assumption that the core is primarily iron was challenged by several scientists in the 1940's, especially W.H. Ramsey, who proposed that the core boundary marks a change in physical but not chemical state. His hypothesis, that the core is a liquid ‘metallized silicate,’ was refuted by research on the properties of silicates at high pressures, but it raised the question whether a theory of the present state of the earth's interior should be consistent with some plausible theory of its origin and development. While Western geophysicists tended to ignore this criterion, a group of Russian scientists developed a theory which satisfied it, although it was difficult to maintain the metallized silicate hypothesis. A compromise model, proposed in the 1970s, involves iron and oxygen in proportions chosen to satisfy density conditions but also derivable by physicochemical evolution from an initially homogeneous earth.",
    url = "https://doi.org/10.1029/eo063i047p01185",
    doi = "10.1029/eo063i047p01185",
    openalex = "W2075901119",
    references = "beckinsale1972the, doi101007bf01454192, doi1010160012821x69901836, doi1010160032063363901132, doi101016s0016703767800139, doi101038194127a0, doi101039jr9370000655, doi101086141260, doi101111j1365246x1926tb05385x, doi101119112026, doi101144gsljgs1906062010421"
}

Major developments in earth structure in the last four years have been concentrated in the description of the earth's lateral heterogeneity: the regions that are heterogenous and the per cent variation of velocity and density in each region. Most studies find that lateral variation is concentrated in the upper 400 and lower 200 km. of the mantle. A radially symmetric earth model has been defined that represents the best average fit to seismic data in a broad frequency band, sampling many regions. P and S velocity is found to increase in zones of 50 km. or less at 400 and 650 to 700 km. depth. The model is transversely anisotropic in the upper mantle. It possesses a vertical axis of symmetry such that the elastic constants are different for vertical propagation than for horizontal and intermediate angles of propagation. The real earth generally exhibits azimuthal anisotropy as well, but the azimuthal anisotropy cannot be resolved by a global average of data. The nature and magnitude of the anisotropy agrees with that found in ultramafic samples of the upper mantle. In attenuation, models of intrinsic attenuation have included the dispersive properties of intrinsic anelasticity and constructed relaxation models consistent with an observed frequency dependence of Q in the body wave band. There has been progress in mapping the scattering properties of the lithosphere. Attenuation due to scattering in the crust and lithosphere has been shown to have strong effects on the amplitudes of seismic waves at local and teleseismic distances.

@article{doi101029rg021i006p01277,
    author = "Cormier, Vernon F.",
    title = "Deep earth structure",
    year = "1983",
    journal = "Reviews of Geophysics",
    abstract = "Major developments in earth structure in the last four years have been concentrated in the description of the earth's lateral heterogeneity: the regions that are heterogenous and the per cent variation of velocity and density in each region. Most studies find that lateral variation is concentrated in the upper 400 and lower 200 km. of the mantle. A radially symmetric earth model has been defined that represents the best average fit to seismic data in a broad frequency band, sampling many regions. P and S velocity is found to increase in zones of 50 km. or less at 400 and 650 to 700 km. depth. The model is transversely anisotropic in the upper mantle. It possesses a vertical axis of symmetry such that the elastic constants are different for vertical propagation than for horizontal and intermediate angles of propagation. The real earth generally exhibits azimuthal anisotropy as well, but the azimuthal anisotropy cannot be resolved by a global average of data. The nature and magnitude of the anisotropy agrees with that found in ultramafic samples of the upper mantle. In attenuation, models of intrinsic attenuation have included the dispersive properties of intrinsic anelasticity and constructed relaxation models consistent with an observed frequency dependence of Q in the body wave band. There has been progress in mapping the scattering properties of the lithosphere. Attenuation due to scattering in the crust and lithosphere has been shown to have strong effects on the amplitudes of seismic waves at local and teleseismic distances.",
    url = "https://doi.org/10.1029/rg021i006p01277",
    doi = "10.1029/rg021i006p01277",
    openalex = "W2064116248",
    references = "doi101029eo063i047p01185"
}

A brief historical introduction to the study of the Earth's core is followed by a review of recent advances in the dynamics of the liquid outer core and the rotation of the solid inner body. In particular, the scaling of the fluid motion equations is reviewed and a detailed derivation of the 'subseismic equation' which governs small-amplitude, low-frequency oscillations is given following methods first outlined by Rochester. Attention is given to the compressibility of the outer core and its role in dynamo theory as well as its effect on Proudman-Taylor flow, where it produces a fluid motion with helicity. The theorem of J.B. Taylor is also generalised to real core compressibility. Rotational motions of the inner core are examined under the strong gravity torque exerted on it by the rest of the Earth. Both the motion ignoring back reaction on the mantle's rotation and the full coupled problem are solved.

@article{doi10108800344885477002,
    author = "Smylie, D. E. and Szeto, A. M. K. and Rochester, M. G.",
    title = "The dynamics of the Earth's inner and outer cores",
    year = "1984",
    journal = "Reports on Progress in Physics",
    abstract = "A brief historical introduction to the study of the Earth's core is followed by a review of recent advances in the dynamics of the liquid outer core and the rotation of the solid inner body. In particular, the scaling of the fluid motion equations is reviewed and a detailed derivation of the 'subseismic equation' which governs small-amplitude, low-frequency oscillations is given following methods first outlined by Rochester. Attention is given to the compressibility of the outer core and its role in dynamo theory as well as its effect on Proudman-Taylor flow, where it produces a fluid motion with helicity. The theorem of J.B. Taylor is also generalised to real core compressibility. Rotational motions of the inner core are examined under the strong gravity torque exerted on it by the rest of the Earth. Both the motion ignoring back reaction on the mantle's rotation and the full coupled problem are solved.",
    url = "https://doi.org/10.1088/0034-4885/47/7/002",
    doi = "10.1088/0034-4885/47/7/002",
    openalex = "W2094882200",
    references = "doi101029eo063i047p01185"
}

The history of the discovery of the earth's liquid core and its role in geophysics is briefly reviewed. Among the core's still undetermined properties is the extent to which its density gradient departs from an adiabat, as characterized by the Brunt‐Vaisala frequency. Since this parameter must affect the eigenfrequencies of the hitherto unobserved inertia‐gravity wave segment of the earth's normal mode spectrum, considerable effort has gone into theoretical studies of these core oscillations over the past decade. We relate these studies to those of internal gravity and Rossby waves in oceanography. The deployment of sensitive gravimeters with long‐term recording capability is now begining to yield data in which core modes may already have been observed.

@article{doi101029eo068i017p0048101,
    author = "Rochester, M. G. and Crossley, David",
    title = "Earth's Third Ocean: The Liquid Core",
    year = "1987",
    journal = "Eos",
    abstract = "The history of the discovery of the earth's liquid core and its role in geophysics is briefly reviewed. Among the core's still undetermined properties is the extent to which its density gradient departs from an adiabat, as characterized by the Brunt‐Vaisala frequency. Since this parameter must affect the eigenfrequencies of the hitherto unobserved inertia‐gravity wave segment of the earth's normal mode spectrum, considerable effort has gone into theoretical studies of these core oscillations over the past decade. We relate these studies to those of internal gravity and Rossby waves in oceanography. The deployment of sensitive gravimeters with long‐term recording capability is now begining to yield data in which core modes may already have been observed.",
    url = "https://doi.org/10.1029/eo068i017p00481-01",
    doi = "10.1029/eo068i017p00481-01",
    openalex = "W2037658639",
    references = "doi101029eo063i047p01185"
}

@misc{cloud1988oasis2,
    author = "Cloud, P",
    title = "Oasis in Space",
    year = "1988",
    howpublished = "Earth History from the Beginning: New York, Norton Books",
    note = "talkorigins\_source = {true}; raw\_reference = {Cloud, P., 1988, Oasis in Space: Earth History from the Beginning: New York, Norton Books.}"
}

@article{doi1010160012821x8890132x,
    author = "Hofmann, Albrecht W.",
    title = "Chemical differentiation of the Earth: the relationship between mantle, continental crust, and oceanic crust",
    year = "1988",
    journal = "Earth and Planetary Science Letters",
    url = "https://doi.org/10.1016/0012-821x(88)90132-x",
    doi = "10.1016/0012-821x(88)90132-x",
    openalex = "W2119438235",
    references = "doi1010160012821x7990013x"
}

@article{doi101016003192018990263x,
    author = "Cross, PA",
    title = "Lecture notes in Earth sciences",
    year = "1989",
    journal = "Physics of The Earth and Planetary Interiors",
    url = "https://doi.org/10.1016/0031-9201(89)90263-x",
    doi = "10.1016/0031-9201(89)90263-x",
    openalex = "W2931574751"
}

This paper focuses upon the process of using curriculum and instructional frameworks to develop a curriculum unit in the earth sciences. The work stems from a graduate level seminar in science education which required participants to use a curriculum framework to design a unit of individualized science instruction. This research was guided by Duschl's thesis that the growth and development of scientific theories can guide decisions about what the most important content is. The paper focuses upon three issues: (1) the need for a thinking curriculum; (2) the rationale behind the curriculum and instructional frameworks; and (3) the rationale behind selecting content for the specific curriculum: the development of theories for the earth's interior structure. The proposed curriculum places the evaluation of six historical models of the earth's interior structure as the focal point of instruction. It includes individual, collaborative, and classroom activities centered around the evaluation and debate of the dynamic roles which evidence, technology, and aims of research have played in the development of scientific models. It offers opportunities for related laboratory and research work, classroom dialogue and presentation, and the individual and social construction of multiple models so as to foster conceptual change in learners and meaningful understanding of the goals and products of scientific endeavor. Contains 34 references. (Author/MDH) *********************************************************************** Reproductions supplied by EDRS are the best that can be made from the original document. *********************************************************************** Using Curriculum Frameworks to Incorporate the History and Nature of Science and Technology into Earth Science Instruction U.S. DEPAIITTMENT OF EDUCATION 011ce al Eaucatronai Research and Improvement EDUCATIONAL RESOURCES INFORMATION CENTER (ERIC) 5:t This document has bee reproduced as recemed from the person Or organization ortginating r Minor changes have been miat tO imprOve reproduction quality hnts at view or opinions staled in this dotu menl do not necessarily represent Oficial OE RI position or polity by Michael J. Smith 4H01 Forbes Quad University of Pittsburgh Pittsburgh, PA 15260 M.1SST35@vms.as.Prrr.EDu PERMISSION TO REPRODUCE THIS MATERIAL HAS BEEN GRANTED BY Mi chap.],Thhn Smith TO THE EDUCATIONAL RESOURCES INFORMATION CENTER (ERIC). Abstract This paper focuses upon the process of using curriculum and instructional frameworks to develop a curriculum unit in the earth sciences. The work stems from a graduate level seminar in science education which required participants to use a curriculum framework to design a unit of individualized science instruction. Curriculum frameworks commonly contain a rationale behind what knowledge, skills, and values they recommend be addressed, some explication of content to be covered, and suggestions as to where and how such recommendations be implemented. Curriculum frameworks are, by their very namre incomplete, requiring added effort and materials to develop a complete scope and sequence, select topics and activities, and resolve issues of management and materials. To answer the curriculum question What to teach?, this research was guided. by Duschl's (1990) thesis that the growth and development of scientific theories can guide decisions about what the most important content is. Thus, the curriculum unit developed here merged Duschl's epistemological perspective that the procedural guidelines that philosophers of science have proposed for explaining the structuring and restructuring of scientific theories can be a tool for classroom teachers with the curriculum and instructional framework for incorporating the history and nature of science and technology into science instruction jointly developed by BSCS and SSEC (1992). This paper focuses upon three issues: 1) the need for a thinking curriculum, 2) the rationale behind the curriculum and instructional frameworks, and 3) the rationale behind selecting content for the specific curriculum: the development of theories for the earth's interior structure. The proposed curriculum places the evaluation of six historical models of the earth's interior structure as the focal point of instruction. It includes individual, collaborative, and classroom activities centered around the evaluation and debate of the dynamic roles which evidence, technology, and aims of research have played in the development of scientific models. It offers opportunities for related laboratory and research work, classroom dialogue and presentation, and the individual and social construction of multiple models so as to foster conceptual change in learners and meaningful understanding of the goals and products of scientific endeavor.This paper focuses upon the process of using curriculum and instructional frameworks to develop a curriculum unit in the earth sciences. The work stems from a graduate level seminar in science education which required participants to use a curriculum framework to design a unit of individualized science instruction. Curriculum frameworks commonly contain a rationale behind what knowledge, skills, and values they recommend be addressed, some explication of content to be covered, and suggestions as to where and how such recommendations be implemented. Curriculum frameworks are, by their very namre incomplete, requiring added effort and materials to develop a complete scope and sequence, select topics and activities, and resolve issues of management and materials. To answer the curriculum question What to teach?, this research was guided. by Duschl's (1990) thesis that the growth and development of scientific theories can guide decisions about what the most important content is. Thus, the curriculum unit developed here merged Duschl's epistemological perspective that the procedural guidelines that philosophers of science have proposed for explaining the structuring and restructuring of scientific theories can be a tool for classroom teachers with the curriculum and instructional framework for incorporating the history and nature of science and technology into science instruction jointly developed by BSCS and SSEC (1992). This paper focuses upon three issues: 1) the need for a thinking curriculum, 2) the rationale behind the curriculum and instructional frameworks, and 3) the rationale behind selecting content for the specific curriculum: the development of theories for the earth's interior structure. The proposed curriculum places the evaluation of six historical models of the earth's interior structure as the focal point of instruction. It includes individual, collaborative, and classroom activities centered around the evaluation and debate of the dynamic roles which evidence, technology, and aims of research have played in the development of scientific models. It offers opportunities for related laboratory and research work, classroom dialogue and presentation, and the individual and social construction of multiple models so as to foster conceptual change in learners and meaningful understanding of the goals and products of scientific endeavor. A paper presented at the 1993 NARST Annual Meeting in Atlanta, Georgia April 18, 1993 The curriculum document that accompanies this paper is available from the author at the above address.

@article{openalexw155124742,
    author = "Smith, Mike J.",
    title = "Using Curriculum Frameworks to Incorporate the History and Nature of Science and Technology into Earth Science Instruction",
    year = "1993",
    abstract = "This paper focuses upon the process of using curriculum and instructional frameworks to develop a curriculum unit in the earth sciences. The work stems from a graduate level seminar in science education which required participants to use a curriculum framework to design a unit of individualized science instruction. This research was guided by Duschl's thesis that the growth and development of scientific theories can guide decisions about what the most important content is. The paper focuses upon three issues: (1) the need for a thinking curriculum; (2) the rationale behind the curriculum and instructional frameworks; and (3) the rationale behind selecting content for the specific curriculum: the development of theories for the earth's interior structure. The proposed curriculum places the evaluation of six historical models of the earth's interior structure as the focal point of instruction. It includes individual, collaborative, and classroom activities centered around the evaluation and debate of the dynamic roles which evidence, technology, and aims of research have played in the development of scientific models. It offers opportunities for related laboratory and research work, classroom dialogue and presentation, and the individual and social construction of multiple models so as to foster conceptual change in learners and meaningful understanding of the goals and products of scientific endeavor. Contains 34 references. (Author/MDH) *********************************************************************** Reproductions supplied by EDRS are the best that can be made from the original document. *********************************************************************** Using Curriculum Frameworks to Incorporate the History and Nature of Science and Technology into Earth Science Instruction U.S. DEPAIITTMENT OF EDUCATION 011ce al Eaucatronai Research and Improvement EDUCATIONAL RESOURCES INFORMATION CENTER (ERIC) 5:t This document has bee reproduced as recemed from the person Or organization ortginating r Minor changes have been miat tO imprOve reproduction quality hnts at view or opinions staled in this dotu menl do not necessarily represent Oficial OE RI position or polity by Michael J. Smith 4H01 Forbes Quad University of Pittsburgh Pittsburgh, PA 15260 M.1SST35@vms.as.Prrr.EDu PERMISSION TO REPRODUCE THIS MATERIAL HAS BEEN GRANTED BY Mi chap.],Thhn Smith TO THE EDUCATIONAL RESOURCES INFORMATION CENTER (ERIC). Abstract This paper focuses upon the process of using curriculum and instructional frameworks to develop a curriculum unit in the earth sciences. The work stems from a graduate level seminar in science education which required participants to use a curriculum framework to design a unit of individualized science instruction. Curriculum frameworks commonly contain a rationale behind what knowledge, skills, and values they recommend be addressed, some explication of content to be covered, and suggestions as to where and how such recommendations be implemented. Curriculum frameworks are, by their very namre incomplete, requiring added effort and materials to develop a complete scope and sequence, select topics and activities, and resolve issues of management and materials. To answer the curriculum question What to teach?, this research was guided. by Duschl's (1990) thesis that the growth and development of scientific theories can guide decisions about what the most important content is. Thus, the curriculum unit developed here merged Duschl's epistemological perspective that the procedural guidelines that philosophers of science have proposed for explaining the structuring and restructuring of scientific theories can be a tool for classroom teachers with the curriculum and instructional framework for incorporating the history and nature of science and technology into science instruction jointly developed by BSCS and SSEC (1992). This paper focuses upon three issues: 1) the need for a thinking curriculum, 2) the rationale behind the curriculum and instructional frameworks, and 3) the rationale behind selecting content for the specific curriculum: the development of theories for the earth's interior structure. The proposed curriculum places the evaluation of six historical models of the earth's interior structure as the focal point of instruction. It includes individual, collaborative, and classroom activities centered around the evaluation and debate of the dynamic roles which evidence, technology, and aims of research have played in the development of scientific models. It offers opportunities for related laboratory and research work, classroom dialogue and presentation, and the individual and social construction of multiple models so as to foster conceptual change in learners and meaningful understanding of the goals and products of scientific endeavor.This paper focuses upon the process of using curriculum and instructional frameworks to develop a curriculum unit in the earth sciences. The work stems from a graduate level seminar in science education which required participants to use a curriculum framework to design a unit of individualized science instruction. Curriculum frameworks commonly contain a rationale behind what knowledge, skills, and values they recommend be addressed, some explication of content to be covered, and suggestions as to where and how such recommendations be implemented. Curriculum frameworks are, by their very namre incomplete, requiring added effort and materials to develop a complete scope and sequence, select topics and activities, and resolve issues of management and materials. To answer the curriculum question What to teach?, this research was guided. by Duschl's (1990) thesis that the growth and development of scientific theories can guide decisions about what the most important content is. Thus, the curriculum unit developed here merged Duschl's epistemological perspective that the procedural guidelines that philosophers of science have proposed for explaining the structuring and restructuring of scientific theories can be a tool for classroom teachers with the curriculum and instructional framework for incorporating the history and nature of science and technology into science instruction jointly developed by BSCS and SSEC (1992). This paper focuses upon three issues: 1) the need for a thinking curriculum, 2) the rationale behind the curriculum and instructional frameworks, and 3) the rationale behind selecting content for the specific curriculum: the development of theories for the earth's interior structure. The proposed curriculum places the evaluation of six historical models of the earth's interior structure as the focal point of instruction. It includes individual, collaborative, and classroom activities centered around the evaluation and debate of the dynamic roles which evidence, technology, and aims of research have played in the development of scientific models. It offers opportunities for related laboratory and research work, classroom dialogue and presentation, and the individual and social construction of multiple models so as to foster conceptual change in learners and meaningful understanding of the goals and products of scientific endeavor. A paper presented at the 1993 NARST Annual Meeting in Atlanta, Georgia April 18, 1993 The curriculum document that accompanies this paper is available from the author at the above address.",
    openalex = "W155124742",
    references = "doi101029eo063i047p01185"
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@article{doi1010160012821x9500123t,
    author = "Allègre, Claude J. and Poirier, Jean-Paul and Humler, Eric and Hofmann, Albrecht W.",
    title = "The chemical composition of the Earth",
    year = "1995",
    journal = "Earth and Planetary Science Letters",
    url = "https://doi.org/10.1016/0012-821x(95)00123-t",
    doi = "10.1016/0012-821x(95)00123-t",
    openalex = "W2048506031",
    references = "doi1010079781461261674, doi1010160016003266902705, doi101098rsta19880066"
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@article{copeland1996education,
    author = "COPELAND, Sandra and KAWACHI, Yosuke and LEE, Daphne",
    title = "Education of Earth Sciences. Earth Science Education in New Zealand.",
    year = "1996",
    journal = "Journal of Geography (Chigaku Zasshi)",
    url = "https://doi.org/10.5026/jgeography.105.6\_779",
    doi = "10.5026/jgeography.105.6\_779",
    number = "6",
    openalex = "W2513880236",
    pages = "779-782",
    volume = "105"
}

Negative carbon isotope anomalies in carbonate rocks bracketing Neoproterozoic glacial deposits in Namibia, combined with estimates of thermal subsidence history, suggest that biological productivity in the surface ocean collapsed for millions of years. This collapse can be explained by a global glaciation (that is, a snowball Earth), which ended abruptly when subaerial volcanic outgassing raised atmospheric carbon dioxide to about 350 times the modern level. The rapid termination would have resulted in a warming of the snowball Earth to extreme greenhouse conditions. The transfer of atmospheric carbon dioxide to the ocean would result in the rapid precipitation of calcium carbonate in warm surface waters, producing the cap carbonate rocks observed globally.

@article{doi101126science28153811342,
    author = "Hoffman, Paul F. and Kaufman, Alan J. and Halverson, Galen P. and Schrag, Daniel P.",
    title = "A Neoproterozoic Snowball Earth",
    year = "1998",
    journal = "Science",
    abstract = "Negative carbon isotope anomalies in carbonate rocks bracketing Neoproterozoic glacial deposits in Namibia, combined with estimates of thermal subsidence history, suggest that biological productivity in the surface ocean collapsed for millions of years. This collapse can be explained by a global glaciation (that is, a snowball Earth), which ended abruptly when subaerial volcanic outgassing raised atmospheric carbon dioxide to about 350 times the modern level. The rapid termination would have resulted in a warming of the snowball Earth to extreme greenhouse conditions. The transfer of atmospheric carbon dioxide to the ocean would result in the rapid precipitation of calcium carbonate in warm surface waters, producing the cap carbonate rocks observed globally.",
    url = "https://doi.org/10.1126/science.281.5381.1342",
    doi = "10.1126/science.281.5381.1342",
    openalex = "W2100634462",
    references = "doi101016000925419500049r, doi1010160012821x84900177, doi1010160016703788903134, doi101016030442039500008f, doi101017s0094837300016808, doi10102994pa01455, doi101038321832a0, doi101038356673a0, doi101038382127a0, doi101126science1585174, doi101126science25250111409, doi101126science2735274452, doi101146annurevearth241191"
}

The Earth is shaped by processes as fleeting as molecular motion and as slow as the movement of tectonic plates. This landmark book is the first comprehensive treatment of the huge range of kinetic processes that lie along the continuum from one of these extremes to the other. A leading researcher in modern geochemistry and geophysics, Antonio Lasaga reviews the theories and quantitative tools that explain these processes, and he shows how they can be applied in the field and laboratory. Chapters focus on such theoretical topics as rate laws of chemical reactions, transport theory, diffusion, irreversible thermodynamics, nucleation theory, and the theory of crystal growth and dissolution. These theories help to explain such kinetic processes as molecular complexation, fluid flow, weathering, oxidation, nucleation, growth, magma generation, biological membrane reactions, atmospheric gas reactions, geochemical cycles, mantle creep, subduction, and erosion. Throughout, Lasaga emphasizes the need to view earth-science phenomena as ongoing processes--to add fully the element of time to models of earth dynamics. He draws on extensive knowledge of geology, chemistry, physics, and mathematics and makes creative use of numerous examples from both nature and the laboratory. Kinetic Theory in the Earth Sciences will be essential reading for geologists and chemists who wish to understand the application of chemical kinetics to the workings of the Earth. Originally published in 1998. The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These editions preserve the original texts of these important books while presenting them in durable paperback and hardcover editions. The goal of the Princeton Legacy Library is to vastly increase access to the rich scholarly heritage found in the thousands of books published by Princeton University Press since its founding in 1905.

@book{doi1015159781400864874,
    author = "Lasaga, Antonio C.",
    title = "Kinetic Theory in the Earth Sciences",
    year = "1998",
    booktitle = "Princeton University Press eBooks",
    abstract = "The Earth is shaped by processes as fleeting as molecular motion and as slow as the movement of tectonic plates. This landmark book is the first comprehensive treatment of the huge range of kinetic processes that lie along the continuum from one of these extremes to the other. A leading researcher in modern geochemistry and geophysics, Antonio Lasaga reviews the theories and quantitative tools that explain these processes, and he shows how they can be applied in the field and laboratory. Chapters focus on such theoretical topics as rate laws of chemical reactions, transport theory, diffusion, irreversible thermodynamics, nucleation theory, and the theory of crystal growth and dissolution. These theories help to explain such kinetic processes as molecular complexation, fluid flow, weathering, oxidation, nucleation, growth, magma generation, biological membrane reactions, atmospheric gas reactions, geochemical cycles, mantle creep, subduction, and erosion. Throughout, Lasaga emphasizes the need to view earth-science phenomena as ongoing processes--to add fully the element of time to models of earth dynamics. He draws on extensive knowledge of geology, chemistry, physics, and mathematics and makes creative use of numerous examples from both nature and the laboratory. Kinetic Theory in the Earth Sciences will be essential reading for geologists and chemists who wish to understand the application of chemical kinetics to the workings of the Earth. Originally published in 1998. The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These editions preserve the original texts of these important books while presenting them in durable paperback and hardcover editions. The goal of the Princeton Legacy Library is to vastly increase access to the rich scholarly heritage found in the thousands of books published by Princeton University Press since its founding in 1905.",
    url = "https://doi.org/10.1515/9781400864874",
    doi = "10.1515/9781400864874",
    openalex = "W1552158845"
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Mass-independent isotopic signatures for delta(33)S, delta(34)S, and delta(36)S from sulfide and sulfate in Precambrian rocks indicate that a change occurred in the sulfur cycle between 2090 and 2450 million years ago (Ma). Before 2450 Ma, the cycle was influenced by gas-phase atmospheric reactions. These atmospheric reactions also played a role in determining the oxidation state of sulfur, implying that atmospheric oxygen partial pressures were low and that the roles of oxidative weathering and of microbial oxidation and reduction of sulfur were minimal. Atmospheric fractionation processes should be considered in the use of sulfur isotopes to study the onset and consequences of microbial fractionation processes in Earth's early history.

@article{doi101126science2895480756,
    author = "Farquhar, James and Bao, Huiming and Thiemens, M. H.",
    title = "Atmospheric Influence of Earth's Earliest Sulfur Cycle",
    year = "2000",
    journal = "Science",
    abstract = "Mass-independent isotopic signatures for delta(33)S, delta(34)S, and delta(36)S from sulfide and sulfate in Precambrian rocks indicate that a change occurred in the sulfur cycle between 2090 and 2450 million years ago (Ma). Before 2450 Ma, the cycle was influenced by gas-phase atmospheric reactions. These atmospheric reactions also played a role in determining the oxidation state of sulfur, implying that atmospheric oxygen partial pressures were low and that the roles of oxidative weathering and of microbial oxidation and reduction of sulfur were minimal. Atmospheric fractionation processes should be considered in the use of sulfur isotopes to study the onset and consequences of microbial fractionation processes in Earth's early history.",
    url = "https://doi.org/10.1126/science.289.5480.756",
    doi = "10.1126/science.289.5480.756",
    openalex = "W2081383679",
    references = "doi1010160016703783901515, doi1010160301926887900015, doi101016s0012821x68800597, doi101029jz070i014p03475, doi101029rg020i002p00280, doi10103835003517, doi101126science27653161217, doi101126science28253931459, doi101126science2835400341, openalexw1569598449"
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The gradual discovery that late Neoproterozoic ice sheets extended to sea level near the equator poses a palaeoenvironmental conundrum. Was the Earth's orbital obliquity > 60° (making the tropics colder than the poles) for 4.0 billion years following the lunar‐forming impact, or did climate cool globally for some reason to the point at which runaway ice‐albedo feedback created a `snowball' Earth? The high‐obliquity hypothesis does not account for major features of the Neoproterozoic glacial record such as the abrupt onsets and terminations of discrete glacial events, their close association with large (> 10‰) negative δ 13 C shifts in seawater proxies, the deposition of strange carbonate layers (`cap carbonates') globally during post‐glacial sea‐level rise, and the return of large sedimentary iron formations, after a 1.1 billion year hiatus, exclusively during glacial events. A snowball event, on the other hand, should begin and end abruptly, particularly at lower latitudes. It should last for millions of years, because outgassing must amass an intense greenhouse in order to overcome the ice albedo. A largely ice‐covered ocean should become anoxic and reduced iron should be widely transported in solution and precipitated as iron formation wherever oxygenic photosynthesis occurred, or upon deglaciation. The intense greenhouse ensures a transient post‐glacial regime of enhanced carbonate and silicate weathering, which should drive a flux of alkalinity that could quantitatively account for the world‐wide occurrence of cap carbonates. The resulting high rates of carbonate sedimentation, coupled with the kinetic isotope effect of transferring the CO 2 burden to the ocean, should drive down the δ 13 C of seawater, as is observed. If cap carbonates are the `smoke' of a snowball Earth, what was the `gun'? In proposing the original Neoproterozoic snowball Earth hypothesis, Joe Kirschvink postulated that an unusual preponderance of land masses in the middle and low latitudes, consistent with palaeomagnetic evidence, set the stage for snowball events by raising the planetary albedo. Others had pointed out that silicate weathering would most likely be enhanced if many continents were in the tropics, resulting in lower atmospheric CO 2 and a colder climate. Negative δ 13 C shifts of 10–20‰ precede glaciation in many regions, giving rise to speculation that the climate was destabilized by a growing dependency on greenhouse methane, stemming ultimately from the same unusual continental distribution. Given the existing palaeomagnetic, geochemical and geological evidence for late Neoproterozoic climatic shocks without parallel in the Phanerozoic, it seems inevitable that the history of life was impacted, perhaps profoundly so.

@article{doi101046j13653121200200408x,
    author = "Hoffman, Paul F. and Schrag, Daniel P.",
    title = "The snowball Earth hypothesis: testing the limits of global change",
    year = "2002",
    journal = "Terra Nova",
    abstract = "The gradual discovery that late Neoproterozoic ice sheets extended to sea level near the equator poses a palaeoenvironmental conundrum. Was the Earth's orbital obliquity > 60° (making the tropics colder than the poles) for 4.0 billion years following the lunar‐forming impact, or did climate cool globally for some reason to the point at which runaway ice‐albedo feedback created a `snowball' Earth? The high‐obliquity hypothesis does not account for major features of the Neoproterozoic glacial record such as the abrupt onsets and terminations of discrete glacial events, their close association with large (> 10‰) negative δ 13 C shifts in seawater proxies, the deposition of strange carbonate layers (`cap carbonates') globally during post‐glacial sea‐level rise, and the return of large sedimentary iron formations, after a 1.1 billion year hiatus, exclusively during glacial events. A snowball event, on the other hand, should begin and end abruptly, particularly at lower latitudes. It should last for millions of years, because outgassing must amass an intense greenhouse in order to overcome the ice albedo. A largely ice‐covered ocean should become anoxic and reduced iron should be widely transported in solution and precipitated as iron formation wherever oxygenic photosynthesis occurred, or upon deglaciation. The intense greenhouse ensures a transient post‐glacial regime of enhanced carbonate and silicate weathering, which should drive a flux of alkalinity that could quantitatively account for the world‐wide occurrence of cap carbonates. The resulting high rates of carbonate sedimentation, coupled with the kinetic isotope effect of transferring the CO 2 burden to the ocean, should drive down the δ 13 C of seawater, as is observed. If cap carbonates are the `smoke' of a snowball Earth, what was the `gun'? In proposing the original Neoproterozoic snowball Earth hypothesis, Joe Kirschvink postulated that an unusual preponderance of land masses in the middle and low latitudes, consistent with palaeomagnetic evidence, set the stage for snowball events by raising the planetary albedo. Others had pointed out that silicate weathering would most likely be enhanced if many continents were in the tropics, resulting in lower atmospheric CO 2 and a colder climate. Negative δ 13 C shifts of 10–20‰ precede glaciation in many regions, giving rise to speculation that the climate was destabilized by a growing dependency on greenhouse methane, stemming ultimately from the same unusual continental distribution. Given the existing palaeomagnetic, geochemical and geological evidence for late Neoproterozoic climatic shocks without parallel in the Phanerozoic, it seems inevitable that the history of life was impacted, perhaps profoundly so.",
    url = "https://doi.org/10.1046/j.1365-3121.2002.00408.x",
    doi = "10.1046/j.1365-3121.2002.00408.x",
    openalex = "W2120852101",
    references = "doi101016001670379290064p, doi101016004019519090116p, doi1010160301926894000708, doi101016s0009254199000819, doi101016s0301926899000820, doi101017s0022336000059977, doi101017s0094837300016808, doi101029jc086ic10p09776, doi101029jd090id01p02167, doi101029rg027i004p00471, doi101038231498a0, doi10103824839, doi101038321832a0, doi10103835036572, doi101038356673a0, doi101111j215334901969tb00466x, doi101126science28153811342, doi101126science28454232129, doi101126science2895480756, doi101130001676061974851869gsaavt20co2, doi101130b250661, doi101130spe70, doi101130spe70p1, doi101144gsjgs14940607, doi1015159780691220239, doi1015159781400864874, doi1016660094837320000260386bpngns20co2, doi10182618200376494199401, doi102110pec88010039, openalexw45631376, wright1978algal"
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@article{doi101016jepsl200509017,
    author = "Steefel, Carl I. and DePaolo, Donald J. and Lichtner, Peter C.",
    title = "Reactive transport modeling: An essential tool and a new research approach for the Earth sciences",
    year = "2005",
    journal = "Earth and Planetary Science Letters",
    url = "https://doi.org/10.1016/j.epsl.2005.09.017",
    doi = "10.1016/j.epsl.2005.09.017",
    openalex = "W2047476280",
    references = "doi101016002532279390147n, doi101016jchemgeo200303001, doi102475ajs2963197"
}

@article{crossref2007intute,
    title = "Intute: Science, Engineering \& Technology: Earth Sciences",
    year = "2007",
    journal = "Choice Reviews Online",
    url = "https://doi.org/10.5860/choice.44-4465",
    doi = "10.5860/choice.44-4465",
    number = "08",
    openalex = "W4231310801",
    pages = "44-4465-44-4465",
    volume = "44"
}

The automation of agricultural mapping using satellite-derived remotely sensed data remains a challenge in Africa because of the heterogeneous and fragmental landscape, complex crop cycles, and limited access to local knowledge. Currently, consistent, continent-wide routine cropland mapping of Africa does not exist, with most studies focused either on certain portions of the continent or at most a one-time effort at mapping the continent at coarse resolution remote sensing. In this research, we addressed these limitations by applying an automated cropland mapping algorithm (ACMA) that captures extensive knowledge on the croplands of Africa available through: (a) ground-based training samples, (b) very high (sub-meter to five-meter) resolution imagery (VHRI), and (c) local knowledge captured during field visits and/or sourced from country reports and literature. The study used 16-day time-series of Moderate Resolution Imaging Spectroradiometer (MODIS) normalized difference vegetation index (NDVI) composited data at 250-m resolution for the entire African continent. Based on these data, the study first produced accurate reference cropland layers or RCLs (cropland extent/areas, irrigation versus rainfed, cropping intensities, crop dominance, and croplands versus cropland fallows) for the year 2014 that provided an overall accuracy of around 90% for crop extent in different agro-ecological zones (AEZs). The RCLs for the year 2014 (RCL2014) were then used in the development of the ACMA algorithm to create ACMA-derived cropland layers for 2014 (ACL2014). ACL2014 when compared pixel-by-pixel with the RCL2014 had an overall similarity greater than 95%. Based on the ACL2014, the African continent had 296 Mha of net cropland areas (260 Mha cultivated plus 36 Mha fallows) and 330 Mha of gross cropland areas. Of the 260 Mha of net cropland areas cultivated during 2014, 90.6% (236 Mha) was rainfed and just 9.4% (24 Mha) was irrigated. Africa has about 15% of the world’s population, but only about 6% of world’s irrigation. Net cropland area distribution was 95 Mha during season 1, 117 Mha during season 2, and 84 Mha continuous. About 58% of the rainfed and 39% of the irrigated were single crops (net cropland area without cropland fallows) cropped during either season 1 (January-May) or season 2 (June-September). The ACMA algorithm was deployed on Google Earth Engine (GEE) cloud computing platform and applied on MODIS time-series data from 2003 through 2014 to obtain ACMA-derived cropland layers for these years (ACL2003 to ACL2014). The results indicated that over these twelve years, on average: (a) croplands increased by 1 Mha/yr, and (b) cropland fallows decreased by 1 Mha/year. Cropland areas computed from ACL2014 for the 55 African countries were largely underestimated when compared with an independent source of census-based cropland data, with a root-mean-square error (RMSE) of 3.5 Mha. ACMA demonstrated the ability to hind-cast (past years), now-cast (present year), and forecast (future years) cropland products using MODIS 250-m time-series data rapidly, but currently, insufficient reference data exist to rigorously report trends from these results.

@article{doi101016jisprsjprs201701019,
    author = "Xiong, Jun and Thenkabail, Prasad S. and Gumma, Murali Krishna and Teluguntla, Pardhasaradhi and Poehnelt, Justin and Congalton, Russell G. and Yadav, Kamini and Thau, David",
    title = "Automated cropland mapping of continental Africa using Google Earth Engine cloud computing",
    year = "2017",
    journal = "ISPRS Journal of Photogrammetry and Remote Sensing",
    abstract = "The automation of agricultural mapping using satellite-derived remotely sensed data remains a challenge in Africa because of the heterogeneous and fragmental landscape, complex crop cycles, and limited access to local knowledge. Currently, consistent, continent-wide routine cropland mapping of Africa does not exist, with most studies focused either on certain portions of the continent or at most a one-time effort at mapping the continent at coarse resolution remote sensing. In this research, we addressed these limitations by applying an automated cropland mapping algorithm (ACMA) that captures extensive knowledge on the croplands of Africa available through: (a) ground-based training samples, (b) very high (sub-meter to five-meter) resolution imagery (VHRI), and (c) local knowledge captured during field visits and/or sourced from country reports and literature. The study used 16-day time-series of Moderate Resolution Imaging Spectroradiometer (MODIS) normalized difference vegetation index (NDVI) composited data at 250-m resolution for the entire African continent. Based on these data, the study first produced accurate reference cropland layers or RCLs (cropland extent/areas, irrigation versus rainfed, cropping intensities, crop dominance, and croplands versus cropland fallows) for the year 2014 that provided an overall accuracy of around 90\% for crop extent in different agro-ecological zones (AEZs). The RCLs for the year 2014 (RCL2014) were then used in the development of the ACMA algorithm to create ACMA-derived cropland layers for 2014 (ACL2014). ACL2014 when compared pixel-by-pixel with the RCL2014 had an overall similarity greater than 95\%. Based on the ACL2014, the African continent had 296 Mha of net cropland areas (260 Mha cultivated plus 36 Mha fallows) and 330 Mha of gross cropland areas. Of the 260 Mha of net cropland areas cultivated during 2014, 90.6\% (236 Mha) was rainfed and just 9.4\% (24 Mha) was irrigated. Africa has about 15\% of the world’s population, but only about 6\% of world’s irrigation. Net cropland area distribution was 95 Mha during season 1, 117 Mha during season 2, and 84 Mha continuous. About 58\% of the rainfed and 39\% of the irrigated were single crops (net cropland area without cropland fallows) cropped during either season 1 (January-May) or season 2 (June-September). The ACMA algorithm was deployed on Google Earth Engine (GEE) cloud computing platform and applied on MODIS time-series data from 2003 through 2014 to obtain ACMA-derived cropland layers for these years (ACL2003 to ACL2014). The results indicated that over these twelve years, on average: (a) croplands increased by 1 Mha/yr, and (b) cropland fallows decreased by 1 Mha/year. Cropland areas computed from ACL2014 for the 55 African countries were largely underestimated when compared with an independent source of census-based cropland data, with a root-mean-square error (RMSE) of 3.5 Mha. ACMA demonstrated the ability to hind-cast (past years), now-cast (present year), and forecast (future years) cropland products using MODIS 250-m time-series data rapidly, but currently, insufficient reference data exist to rigorously report trends from these results.",
    url = "https://doi.org/10.1016/j.isprsjprs.2017.01.019",
    doi = "10.1016/j.isprsjprs.2017.01.019",
    openalex = "W2592712793",
    references = "doi101080014311612014930202"
}

@article{doi101038s4158601909121,
    author = "Reichstein, Markus and Camps‐Valls, Gustau and Stevens, Björn and Jung, Martin and Denzler, Joachim and Carvalhais, Nuno and Prabhat",
    title = "Deep learning and process understanding for data-driven Earth system science",
    year = "2019",
    journal = "Nature",
    url = "https://doi.org/10.1038/s41586-019-0912-1",
    doi = "10.1038/s41586-019-0912-1",
    openalex = "W2913323966",
    references = "doi1010160022169470902556, doi101016jneunet201409003, doi101038261459a0, doi101038nature14539, doi101109cvpr20095206848, doi101126science1244693, doi101162neco1997981735, doi1011752009jcli29091, doi101175jclid12005791, doi103156jsoft2951772, openalexw2557283755"
}

Land cover mapping of large areas is challenging due to the significant volume of satellite data to acquire and process, as well as the lack of spatial continuity due to cloud cover. Temporal aggregation—the use of metrics (i.e., mean or median) derived from satellite data over a period of time—is an approach that benefits from recent increases in the frequency of free satellite data acquisition and cloud-computing power. This enables the efficient use of multi-temporal data and the exploitation of cloud-gap filling techniques for land cover mapping. Here, we provide the first formal comparison of the accuracy between land cover maps created with temporal aggregation of Sentinel-1 (S1), Sentinel-2 (S2), and Landsat-8 (L8) data from one-year and test whether this method matches the accuracy of traditional approaches. Thirty-two datasets were created for Wales by applying automated cloud-masking and temporally aggregating data over different time intervals, using Google Earth Engine. Manually processed S2 data was used for comparison using a traditional two-date composite approach. Supervised classifications were created, and their accuracy was assessed using field-based data. Temporal aggregation only matched the accuracy of the traditional two-date composite approach (77.9%) when an optimal combination of optical and radar data was used (76.5%). Combined datasets (S1, S2 or S1, S2, and L8) outperformed single-sensor datasets, while datasets based on spectral indices obtained the lowest levels of accuracy. The analysis of cloud cover showed that to ensure at least one cloud-free pixel per time interval, a maximum of two intervals per year for temporal aggregation were possible with L8, while three or four intervals could be used for S2. This study demonstrates that temporal aggregation is a promising tool for integrating large amounts of data in an efficient way and that it can compensate for the lower quality of automatic image selection and cloud masking. It also shows that combining data from different sensors can improve classification accuracy. However, this study highlights the need for identifying optimal combinations of satellite data and aggregation parameters in order to match the accuracy of manually selected and processed image composites.

@article{doi103390rs11030288,
    author = "Carrasco, Luis and O’Neil, Aneurin W. and Morton, Richard and Rowland, Clare S.",
    title = "Evaluating Combinations of Temporally Aggregated Sentinel-1, Sentinel-2 and Landsat 8 for Land Cover Mapping with Google Earth Engine",
    year = "2019",
    journal = "Remote Sensing",
    abstract = "Land cover mapping of large areas is challenging due to the significant volume of satellite data to acquire and process, as well as the lack of spatial continuity due to cloud cover. Temporal aggregation—the use of metrics (i.e., mean or median) derived from satellite data over a period of time—is an approach that benefits from recent increases in the frequency of free satellite data acquisition and cloud-computing power. This enables the efficient use of multi-temporal data and the exploitation of cloud-gap filling techniques for land cover mapping. Here, we provide the first formal comparison of the accuracy between land cover maps created with temporal aggregation of Sentinel-1 (S1), Sentinel-2 (S2), and Landsat-8 (L8) data from one-year and test whether this method matches the accuracy of traditional approaches. Thirty-two datasets were created for Wales by applying automated cloud-masking and temporally aggregating data over different time intervals, using Google Earth Engine. Manually processed S2 data was used for comparison using a traditional two-date composite approach. Supervised classifications were created, and their accuracy was assessed using field-based data. Temporal aggregation only matched the accuracy of the traditional two-date composite approach (77.9\%) when an optimal combination of optical and radar data was used (76.5\%). Combined datasets (S1, S2 or S1, S2, and L8) outperformed single-sensor datasets, while datasets based on spectral indices obtained the lowest levels of accuracy. The analysis of cloud cover showed that to ensure at least one cloud-free pixel per time interval, a maximum of two intervals per year for temporal aggregation were possible with L8, while three or four intervals could be used for S2. This study demonstrates that temporal aggregation is a promising tool for integrating large amounts of data in an efficient way and that it can compensate for the lower quality of automatic image selection and cloud masking. It also shows that combining data from different sensors can improve classification accuracy. However, this study highlights the need for identifying optimal combinations of satellite data and aggregation parameters in order to match the accuracy of manually selected and processed image composites.",
    url = "https://doi.org/10.3390/rs11030288",
    doi = "10.3390/rs11030288",
    openalex = "W2913065079",
    references = "doi1010801947568320161164247"
}

Indonesia has the largest tropical peatlands in the world covered an area of 14.91 \nmillion ha. Peatlands play an important role in global carbon sequestration. This study aimed \nto: a] map the peatland in Pesisir Selatan, Sumatra Barat calculate the soil carbon stock in the \npeatlands on various land use and peat thickness and c] identify the relationship of soil \ncharacteristics to the soil carbon. We investigated thirty soil samples in Pesisir Selatan. The \nland-use types on peatland in Pesisir Selatan consisted of forest [GH], shrub [GS], oil palm \nplantations [GPs], annual cropland[GLp], and bareland [GLp]. The results showed that the \ntotal area of peatlands inPesisir Selatan is 78,998.74 ha, while the total amount of soil carbon \nstocks is 244 million tonnes, and the sequence follows GPs> GS> GH> GT>GLp. The average \nvalue of soil carbon stock is 3,090.89 per ha, the sequence follows GH> GS> GT> GPs>GLp. \nHence, the average amount of soil carbon stock based on depth is 8,529 tons for peat depth \n>600cm, 4,082 tons for peat depth 300-600 cm, and 525 tons for peat depth 0-300 cm. \nDifferences in average values of soil carbon stock per ha are highly influenced by the \ndifferences in peat thickness. The dynamics of total carbon show a higher its content in the \nsubsurface layer rather than in the surface layer. The soil carbon is linearly correlated with \nwater content and it is inversely proportional to bulk density. \nKeywords: digital mapping, peat, satellite imagery, soil carbon stock

@inproceedings{doi101088issn17551315,
    author = "Hermansah, Hermansah and Sandi, Nofrita and Naspendra, Zuldadan",
    title = "IOP Conference Series: Earth and Environmental Science",
    year = "2020",
    booktitle = "IOP Conference Series Earth and Environmental Science",
    abstract = "Indonesia has the largest tropical peatlands in the world covered an area of 14.91 \nmillion ha. Peatlands play an important role in global carbon sequestration. This study aimed \nto: a] map the peatland in Pesisir Selatan, Sumatra Barat calculate the soil carbon stock in the \npeatlands on various land use and peat thickness and c] identify the relationship of soil \ncharacteristics to the soil carbon. We investigated thirty soil samples in Pesisir Selatan. The \nland-use types on peatland in Pesisir Selatan consisted of forest [GH], shrub [GS], oil palm \nplantations [GPs], annual cropland[GLp], and bareland [GLp]. The results showed that the \ntotal area of peatlands inPesisir Selatan is 78,998.74 ha, while the total amount of soil carbon \nstocks is 244 million tonnes, and the sequence follows GPs> GS> GH> GT>GLp. The average \nvalue of soil carbon stock is 3,090.89 per ha, the sequence follows GH> GS> GT> GPs>GLp. \nHence, the average amount of soil carbon stock based on depth is 8,529 tons for peat depth \n>600cm, 4,082 tons for peat depth 300-600 cm, and 525 tons for peat depth 0-300 cm. \nDifferences in average values of soil carbon stock per ha are highly influenced by the \ndifferences in peat thickness. The dynamics of total carbon show a higher its content in the \nsubsurface layer rather than in the surface layer. The soil carbon is linearly correlated with \nwater content and it is inversely proportional to bulk density. \nKeywords: digital mapping, peat, satellite imagery, soil carbon stock",
    url = "https://doi.org/10.1088/issn.1755-1315",
    doi = "10.1088/issn.1755-1315",
    openalex = "W3208261418",
    references = "doi101007s105330079109z, doi101016jgeoderma200911013, doi101016jgeoderma201710018, doi101016jmarpetgeo201402020, doi101016jscitotenv201902420, doi101093oso97801951208370030006, doi101111j13652486201002279x, doi101111j14752743200900219x, doi1023071941811, doi104141cjss06008"
}

@article{doi103724spj7103161536,
    title = "Bulletin of the Chinese Academy of Sciences",
    year = "2020",
    journal = "Bulletin of the Chinese Academy of Sciences",
    url = "https://doi.org/10.3724/sp.j.7103161536",
    doi = "10.3724/sp.j.7103161536",
    openalex = "W4231539591"
}

@article{doi101016jearscirev2021103503,
    author = "Scotese, Christopher R. and Song, Haijun and Mills, Benjamin and van der Meer, Douwe G.",
    title = "Phanerozoic paleotemperatures: The earth’s changing climate during the last 540 million years",
    year = "2021",
    journal = "Earth-Science Reviews",
    url = "https://doi.org/10.1016/j.earscirev.2021.103503",
    doi = "10.1016/j.earscirev.2021.103503",
    openalex = "W3120450552",
    references = "doi10100797894017960024, doi1010160016703789901506, doi101016003101828790040x, doi1010160031018292901825, doi101016jcretres200805025, doi101016jearscirev201305014, doi101016jepsl200905028, doi101016jgr201212026, doi101016jmargeo200502007, doi101016jpalaeo200606026, doi101016jpalaeo200911006, doi101016jpalaeo201005036, doi101016jpalaeo201409013, doi101016jpalaeo201611005, doi101016jpalaeo201703014, doi101016jpalwor200610016, doi101016s0009254199000819, doi101016s0009254199000844, doi101016s0012825200000374, doi101016s0012825202001046, doi101016s0012825299000483, doi101016s1631071303000063, doi101017cbo9780511628948, doi101017s0016756818000110, doi1010292009gc002788, doi101038333547a0, doi101038ncomms14845, doi101038s41467018039961, doi101038s4156101700036, doi101046j13653121200200408x, doi101073pnas1319253111, doi101086648217, doi101111j14754983201201165x, doi101126sciadvaaz1346, doi101126science1155814, doi101126science1161648, doi101126science1177265, doi101126science2064415217, doi101126science21545381351, doi101126science2845414616, doi1011300016760619637493sitcio20co2, doi10113000167606198596567defie20co2, doi1011300016760619991110960cisona23co2, doi1011300091761319880160022lctvan23co2, doi1011300091761319910190867ccapct23co2, doi1011302019254214, doi101130g315791, doi101130gsab471177, doi101146annurevea05050177001535, doi101146annurevearth040610133431, doi1015159781400862924, doi1016660094837320040300522oeamdo20co2, doi105194cp1714832021, doi105194cp76032011, doi105860choice435903, openalexw2106559152, openalexw2139291338, openalexw2989964553"
}

Mapping the distribution and type of land use and land cover (LULC) is essential for watershed management. The Tigris-Euphrates basin is a transboundary region in the Middle East shared between six countries, but a recent fine-scale LULC map of the area is lacking. Using Landsat-8 time series, a 30-m resolution LULC map was produced for the Tigris-Euphrates basin. In total, 1184 Landsat scenes were processed within the Google Earth Engine (GEE). For the collection of ground truth data, differential manifestations of green cover were considered by dividing the study area into five climatic regions and the training samples were taken from each sub-region. To account for the temporal variation of LULC types, six two-month interval composite layers, including the spectral and thermal bands of Landsat-8, texture and spectral indices, as well as topographic factors were created for the target year 2019. Image segmentation and classification were performed using the simple non-iterative clustering (SNIC) and Random Forest (RF) algorithms, respectively. A computationally effective parallel processing approach was developed, which created a number of tiles and sub-tiles and a bulk command was converted into smaller parallel commands. The generated LULC map showed a satisfactory overall accuracy of 91.7%, with the highest User’s accuracy in water and wetland, and the lowest in rainfed crop and rangeland and the highest Producer’s accuracy in water and barren areas, and the lowest in garden and rangeland. This study highlights the necessity of using multi-temporal data for LULC mapping, in particular, multi-temporal NDVI, for the separation of different green cover types in arid and semi-arid environment.

@article{doi1010801548160320211947623,
    author = "Shafizadeh‐Moghadam, Hossein and Khazaei, Morteza and Alavipanah, Seyed Kazem and Weng, Qihao",
    title = "Google Earth Engine for large-scale land use and land cover mapping: an object-based classification approach using spectral, textural and topographical factors",
    year = "2021",
    journal = "GIScience \& Remote Sensing",
    abstract = "Mapping the distribution and type of land use and land cover (LULC) is essential for watershed management. The Tigris-Euphrates basin is a transboundary region in the Middle East shared between six countries, but a recent fine-scale LULC map of the area is lacking. Using Landsat-8 time series, a 30-m resolution LULC map was produced for the Tigris-Euphrates basin. In total, 1184 Landsat scenes were processed within the Google Earth Engine (GEE). For the collection of ground truth data, differential manifestations of green cover were considered by dividing the study area into five climatic regions and the training samples were taken from each sub-region. To account for the temporal variation of LULC types, six two-month interval composite layers, including the spectral and thermal bands of Landsat-8, texture and spectral indices, as well as topographic factors were created for the target year 2019. Image segmentation and classification were performed using the simple non-iterative clustering (SNIC) and Random Forest (RF) algorithms, respectively. A computationally effective parallel processing approach was developed, which created a number of tiles and sub-tiles and a bulk command was converted into smaller parallel commands. The generated LULC map showed a satisfactory overall accuracy of 91.7\%, with the highest User’s accuracy in water and wetland, and the lowest in rainfed crop and rangeland and the highest Producer’s accuracy in water and barren areas, and the lowest in garden and rangeland. This study highlights the necessity of using multi-temporal data for LULC mapping, in particular, multi-temporal NDVI, for the separation of different green cover types in arid and semi-arid environment.",
    url = "https://doi.org/10.1080/15481603.2021.1947623",
    doi = "10.1080/15481603.2021.1947623",
    openalex = "W3184629543",
    references = "doi1010801947568320161164247"
}

@misc{crossrefNonescience,
    title = "Science China Earth Sciences",
    year = "None",
    url = "https://doi.org/10.1007/11430.1869-1897",
    doi = "10.1007/11430.1869-1897",
    openalex = "W4242967994"
}