SELECTED ARTICLES

Download CV for a full list of publications. [PDF 512 KB]

Twenty-three articles with more than 100 citations; more than 8,000 total citations; h-index = 41.
(Data from Science Citation Index Expanded and Google Scholar)

*former Ph.D. student;

†postdoctoral research scientist or fellow.

1. Deformation and basin formation along strike-slip faults [download PDF 22.2 MB]

This paper, which is among my most highly cited, was an outgrowth of lectures prepared for Exxon schools in structural analysis and basin tectonics in the early 1980s, and my six years in southern California. It still represents one of the best available summaries of the geological attributes of strike-slip basins. Kevin Biddle, who joined Exxon just two years before I did, remained with the corporation until his retirement in 2014.

Christie-Blick, N., and Biddle, K.T., 1985, Deformation and basin formation along strike-slip faults, in Biddle, K.T., and Christie-Blick, N., eds., Strike-Slip Deformation, Basin Formation, and Sedimentation: Society of Economic Paleontologists and Mineralogists Special Publication No. 37, p. 1-34.

2. Sequence stratigraphy in Proterozoic successions [download PDF 532 KB]

This paper and two Geological Society of America abstracts published in 1985 represent the first application of sequence stratigraphic principles in Proterozoic rocks.

Christie-Blick, N., †Grotzinger, J.P., and von der Borch, C.C., 1988, Sequence stratigraphy in Proterozoic successions: Geology, v. 16, p. 100-104.

3. Pre-Mesozoic palinspastic reconstruction of the eastern Great Basin (western United States) [download PDF 2.4 MB]

In putting together a pre-Mesozoic palinspastic reconstruction for the eastern Great Basin, we made two simplifying assumptions. One was to accept the recently published pre-Miocene reconstruction of Wernicke et al. (1988) for the transect between the Sierra Nevada and Colorado Plateau at the latitude of Las Vegas. The other was to assume on the basis of available paleomagnetic data that the Sierra Nevada had experienced little or no net rotation. Initially presented as a poster at the Denver Centennial meeting of the Geological Society of America in 1988, the reconstruction attracted a lot of attention. Given what we have learned over the past few years in the central Basin and Range Province (e.g., Anders et al., 2006, Journal of Geology, v. 114, p. 645-664; Renik et al., 2008, Journal of Sedimentary Research, v. 78, p.199-219), it is now our view that the magnitude of late Cenozoic crustal extension will prove to be appreciably smaller than we assumed in 1989.

*Levy, M., and Christie-Blick, N., 1989, Pre-Mesozoic palinspastic reconstruction of the eastern Great Basin (western United States): Science, v. 245, p. 1454-1462.

4. Working hypotheses for the origin of the Wonoka canyons (Neoproterozoic), South Australia [download PDF 12 MB]

This paper focuses on a series of intriguing kilometer-deep incised valleys of late Neoproterozoic age in the Flinders Ranges of South Australia. It’s significance is in working through the full range of explanations permitted by available evidence at that time. Field work completed in the 1990s, but not yet properly published, reinforced the view that the canyons were cut subaerially, most likely as a result of the desiccation of a marine embayment  temporarily cut off from the open ocean.

Christie-Blick, N., von der Borch, C.C., DiBona, P.A., 1990, Working hypotheses for the origin of the Wonoka canyons (Neoproterozoic), South Australia: American Journal of Science, v. 290-A (Cloud volume), p. 295-332.

5. Onlap, offlap, and the origin of unconformity-bounded depositional sequences [download PDF 2.4 MB]

This paper is an extension of my 1990 National Academy of Sciences article on the seismic stratigraphic record of sea-level change, and a second attempt to communicate a conclusion that had struck me as self-evident since around 1984, but that is still not widely appreciated or accepted. Unconformities or sequence boundaries develop over a finite interval of geological time, not instantaneously, and they don’t necessarily have anything to do with sea-level change.

Christie-Blick, N., 1991, Onlap, offlap, and the origin of unconformity-bounded depositional sequences: Marine Geology, v. 97, p. 35-56.

6. Tectonic subsidence of the early Paleozoic passive continental margin in eastern California and southern Nevada  [download PDF 1.8 MB]

The significance of this paper is that we investigated the subsidence history of a Cambro-Ordovician passive continental margin in a region in which post-rift thermal subsidence can be compared directly with evidence for crustal extension in underlying Proterozoic rocks. The mismatch that emerged, and that later work indicates is common at younger passive margins, is best explained by inhomogeneous extension of the continental lithosphere. The paper is notable also for quantifying early Paleozoic eustatic change. Most of what passes for sea-level change in the Paleozoic literature is a local assessment of changes in paleowater depth (a different term in the backstripping equation). Subsequent revision of the Cambrian timescale only amplifies the basic conclusions, though details could be usefully revisited.

*Levy, M., and Christie-Blick, N., 1991, Tectonic subsidence of the early Paleozoic passive continental margin in eastern California and southern Nevada: Geological Society of America Bulletin, v. 103, p. 1590-1606.

7. Is the Sevier Desert reflection of west-central Utah a normal fault?

[download PDF 532 KB]

The abundance of healed and partially healed microfractures in quartz particles recovered from cuttings from two wells in the Sevier Desert is invariant with depth, contrary to what might be expected above a detachment fault with several tens of kilometers of displacement. This paper was very controversial at the time because the existence of a regional-scale low-angle normal fault had been generally accepted since the mid-1970s, based upon the interpretation of seismic reflection data. Not much changed in that regard over the next decade or so, in spite of a series of papers extending the initial conclusions (e.g., Anders et al., 2001, Geological Society of America Bulletin, v. 113, p. 895-907; Wills et al., 2005, American Journal of Science, v. 305, p. 42-100; Christie-Blick et al., 2007, Geological Society of London Special Publication No. 282, p. 419-439). However, strong community support has emerged for scientific drilling and making in situ measurements in the Sevier Desert basin, under the auspices of the International Continental Scientific Drilling Program, to test the detachment hypothesis and to determine the conditions under which the fault may have slipped.

Anders, M.H., and Christie-Blick, N., 1994, Is the Sevier Desert reflection of west-central Utah a normal fault?: Geology, v. 22, p. 771-774.

8. Sequence stratigraphy [download PDF 2 MB]

This paper tends to be cited more frequently than it is read. The intent was to balance the generally accepted essence of sequence stratigraphy with an evaluation of practical shortcomings – foremost of which are the subjective interpretation of systems tracts, and a tendency to ignore the role of tectonic phenomena, even in sedimentary basins in which stratal geometry is clearly influenced by deformation. I credit Rex Cole of Unocal (and now Mesa State College) for drawing my attention to the absence of detached lowstand sandstones in the late Cretaceous foreland of eastern Utah and western Colorado – unintentionally providing critical support for the idea that in most sedimentary basins, incised valleys are fundamentally highstand rather than lowstand features.

Christie-Blick, N., and *Driscoll, N.W., 1995, Sequence stratigraphy: Annual Review of Earth and Planetary Sciences, v. 23, p. 451-478.

9. Sequence stratigraphy and the interpretation of Neoproterozoic earth history [download PDF 2.3 MB]

This paper deals with practical issues for the sequence stratigraphic interpretation of Proterozoic successions, with examples drawn from the Flinders Ranges of South Australia. It also makes a specific recommendation for the location of what became the base-Ediacaran Global Boundary Stratotype Section and Point (GSSP) from the perspective of sequence stratigraphy (Knoll et al., 2004, Science, v. 305, p. 621-622; Knoll et al., 2006, Lethaia, v. 39, p. 13-30).

Christie-Blick, N., Dyson, I.A., and von der Borch, C.C., 1995, Sequence stratigraphy and the interpretation of Neoproterozoic earth history, in Knoll, A.H., and Walter, M., eds., Neoproterozoic Stratigraphy and Earth History: Precambrian Research, v. 73 (special volume), p. 3-26.

10. Paleomagnetic polarity reversals in Marinoan (ca. 600 Ma) glacial deposits of Australia: Implications for the duration of low-latitude glaciation in Neoproterozoic time  [download PDF 1.8 MB]

More than 40 years after Brian Harland first floated the idea of Proterozoic equatorial glaciation, Linda Sohl’s paper provided definitive evidence for the near-depositional age of the low-inclination C component of magnetization in the glaciogenic Elatina Formation (a positive regional fold test, and evidence for multiple polarity reversals). Initial data were first presented to a packed room at the 1995 annual meeting of the Geological Society of America, and they materially influenced the development of the snowall Earth hypothesis (P.F. Hoffman et al., 1998, Science, v. 281, p. 1342-1346). Linda deserves credit for collecting a set of pilot samples during her first field season in Australia (1993), in spite of my lukewarm support for tackling a problem that had long stymied those with considerably more experience in paleomagnetics. That things worked out was due to a combination of good luck, and dogged processing of a huge number of samples. Ironically, while the snowball Earth contributed to a sea change in opinion, from general doubt about the viability of equatorial glaciation to widespread support for the idea that the Earth may have remained totally ice-covered for millions of years under what were effectively super-greenhouse conditions, the hypothesis failed more or less immediately to withstand scrutiny (e.g., Christie-Blick et al., 1999, Science, v. 284, p. 1087; Kennedy et al., 2001, Geology, v. 29, p. 1135-1138).

*†Sohl, L.E., Christie-Blick, N., and Kent, D.V., 1999, Paleomagnetic polarity reversals in Marinoan (ca. 600 Ma) glacial deposits of Australia: Implications for the duration of low-latitude glaciation in Neoproterozoic time: Geological Society of America Bulletin, v. 111, p. 1120-1139.

11. Are Proterozoic cap carbonates and isotopic excursions a record of gas hydrate destabilization following Earth's coldest intervals?  [download PDF 220 KB]

This is the first of a series of papers promoting an alternative to the snowball Earth. Martin Kennedy and I had spent a field season in Australia in 1995 looking at weird fabrics that he had first noted are widely developed in cap carbonates (Kennedy, 1996, Journal of Sedimentary Research, v. 66, p. 1050-1064), and I had become intrigued by Gerry Dickens’s explanation for the late Paleocene carbon isotope excursion in terms of the degradation of methane hydrates. We reasoned that methane hydrates ought to have been extraordinarily abundant on a planet sufficiently cold to support low-latitude glaciation. So we suggested methane release as a way to account for diverse evidence for syn-depositional disruption of the carbonates and, at a global scale, for the marked negative carbon isotope anomaly with which they are commonly associated.

†Kennedy, M.J., Christie-Blick, N., and *†Sohl, L.E., 2001, Are Proterozoic cap carbonates and isotopic excursions a record of gas hydrate destabilization following Earth's coldest intervals?Geology, v. 29, p. 443-446.

12. Evaluating the stratigraphic response to eustasy from Oligocene strata in New Jersey  [download PDF 312 KB]

Sequence boundaries in the New Jersey Oligocene correspond with eustatic lows, and condensed sections (intervals of sediment starvation) with eustatic highs. The conclusion is significant because according to standard concepts in sequence stratigraphy, for an up-dip location at an old passive continental margin, where rates of glacially modulated sea-level change ought to have been as much as an order of magnitude greater than the rate of subsidence, sequence boundaries would be expected to form early, as sea level began to fall. The unexpected phase lag corresponds with almost half a cycle.

†Pekar, S.F., Christie-Blick, N., Kominz, M.A., and Miller, K.G., 2001, Evaluating the stratigraphic response to eustasy from Oligocene strata in New Jersey: Geology, v. 29, p. 55-58.

13. Sequence stratigraphy of the Neoproterozoic Infra Krol Formation and Krol Group, Lesser Himalaya, India  [download PDF 1.7 MB]

This is a particularly nice example of sequence stratigraphic analysis in a Neoproterozoic succession, with intriguing implications for chemostratigraphy in old rocks. The paper also departs markedly from previously published interpretations of Lesser Himalayan stratigraphy and sedimentology. Regional stratigraphic discontinuities were traced over a distance of nearly 300 km in an oblique cross-section through the Krol platform. Three of the surfaces are interpreted as sequence boundaries on the basis of locally developed incised valleys and breccia-filled paleokarstic depressions. Inconsistencies in the stratigraphic location of carbon isotopic minima with respect to unconformities raise doubts about the interpretation of such data in isolated sections elsewhere. That it took an additional four years to publish the details of the geochemical data (Kaufman et al., 2006, Precambrian Research, v. 147, p. 156-185), with minimal conclusions, reflects a continuing lack of agreement among the authors with respect to the significance of those data. A companion paper (Jiang et al., Sedimentology, v. 50, p. 921-952) deals with details of the sedimentology and sedimentary cyclicity.

*Jiang Ganqing, Christie-Blick, N., Kaufman, A.J., Banerjee, D.M., and Rai, V., 2002, Sequence stratigraphy of the Neoproterozoic Infra Krol Formation and Krol Group, Lesser Himalaya, India: Journal of Sedimentary Research, v. 72, p. 524-542.

14. Calibration between eustatic estimates from backstripping and oxygen isotopic records for the Oligocene  [download PDF 480 KB]

A long-standing goal in the quantification of ancient sea-level change was to merge constraints from passive continental margins with deep-sea oxygen isotope data. This paper is notable for accomplishing that goal for the first time, and for deriving the first pre-Pleistocene calibration between sea-level change and δ18O (0.10‰-0.13‰/10 m for Oligocene time). The paper also draws attention to the important difference between eustasy and what we term apparent sea-level change. In the case of eustasy, the reference frame is the center of the Earth, or at least a continental interior acting as a proxy for stability.). As sea level rises and falls eustatically, flooded portions of the crust undergo water loading or unloading, so that observed fluctuations in water depth (apparent sea-level change) exceed the eustatic changes that were responsible by a factor of ~1.48. The oxygen isotope calibration refers to this larger figure.

†Pekar, S.F., Christie-Blick, N., Kominz, M.A., and Miller, K.G., 2002, Calibration between eustatic estimates from backstripping and oxygen isotopic records for the Oligocene: Geology, v. 30, p. 903-906.

15. Quantitative constraints on the origin of stratigraphic architecture at passive continental margins: Oligocene sedimentation in New Jersey, U.S.A.  [download PDF 1.2 MB]

This article is the last of a series that Steve Pekar and I put together as an extension of his Ph.D. research at Rutgers University. The unifying idea for the paper was to evaluate all of the factors governing Oligocene sedimentation and sequence development at the New Jersey margin. Among key conclusions: The unexpected correspondence of sequence boundaries with eustatic minima and the absence of lowstand deposits in this example relates to an active wave climate that permitted the efficient transfer of sediment across the shallow shelf, and prevented the development of point sources. The paper was selected as the outstanding contribution in the Journal of Sedimentary Research for 2003. Ironically, given the general significance of the conclusions, the paper had yet to garner a single literature citation at the time the award was made two years after publication.

†Pekar, S.F., Christie-Blick, N., Miller, K.G., and Kominz, M.A., 2003, Quantitative constraints on the origin of stratigraphic architecture at passive continental margins: Oligocene sedimentation in New Jersey, U.S.A.: Journal of Sedimentary Research, v. 73, p. 227-245.

16. Stable isotopic evidence for methane seeps in Neoproterozoic postglacial cap carbonates  [download PDF 564 KB]

An obvious criticism of the methane hydrate hypothesis (Kennedy et al., 2001, Geology, v. 29, p. 443-446) was the apparent absence of the large local variations in carbon isotopic composition that might be expected in the vicinity of cold seeps. Analyses of limestone peloids, clots and fringing cements in marine tepee-like structures in the Doushantuo cap carbonate of South China reveal δ13C values ranging from +5‰ to –41‰. Comparable data have now been obtained at other locations. Among implications: dolomitization of the cap in many places may have resulted in partial re-equilibration of isotopic values, as we had long suspected.

*Jiang Ganqing, †Kennedy, M.J., and Christie-Blick, N., 2003, Stable isotopic evidence for methane seeps in Neoproterozoic postglacial cap carbonates: Nature, v. 426, p. 822-826.

17. A new period for the geologic time scale  [download PDF 184 KB]

This paper and two related articles (Knoll et al., 2004, Episodes, v. 27, p. 222; Knoll et al., 2006, Lethaia, v. 39, p. 13-30) constitute the final product of 16 years of work by the Subcommission on the Terminal Proterozoic System of the International Union of Geological Sciences (IUGS). Andy Knoll was the chair of the subcommission. I was lead proponent (with Martin Kennedy and Linda Sohl) for one of two proposals for the ultimately successful location. The Enorama Creek section in the Flinders Ranges, Australia, and the Nuccaleena post-glacial cap carbonate level in that section, were endorsed by IUGS in 2004 as a Global Boundary Stratotype Section and Point (GSSP) formally marking the base of a newly defined system and the beginning of a period of pre-Cambrian geological time (Ediacaran, 635 to 542 Ma). The same level at nearby Bunyeroo Gorge had been promoted, unsuccessfully at the time, as the base of a system with the same name by Preston Cloud and Martin Glaessner (1982, Science, v. 217, p. 783-792). Cloud, who died in 1991, was a member of my Ph.D. advisory committee at the University of California, Santa Barbara in the late 1970s. My own work in Australia began in 1986.

Knoll, A.H., Walter, M.R., Narbonne, G.M., and Christie-Blick, N., 2004, A new period for the geologic time scale: Science, v. 305, p. 621-622.

18. Water shortages, development, and drought in Rockland County, New York  [download PDF 11.6 MB]

An examination of climate data over the past century reveals that the severity of recent droughts in Rockland County in the suburbs of New York City is well within the range of past variability. Rather than climate alone, shortfalls in the domestic water supply, beginning in the 1990s, are due to an increasing mismatch between supply and demand as the population of the county increased over several decades. The situation is not likely to improve so long as planning and zoning in the State of New York remain effectively decoupled from decision-making with respect to water resources.

Lyon, B., Christie-Blick, N., and Gluzberg, Y., 2005, Water shortages, development, and drought in Rockland County, New York: Journal of American Water Resources Association, December, p. 1457-1469.

19. The Phanerozoic record of global sea-level change  [download PDF 568 KB]

A serious effort to investigate global changes in sea level under the auspices of the Ocean Drilling Program, and later the Integrated Ocean Drilling Program, dates back to the Second Conference on Scientific Ocean Drilling (COSOD II), organized in Strasbourg, France in 1987. This paper pulls together more than two decades of work by numerous scientists, including a core group based at Rutgers University and Lamont-Doherty Earth Observatory. All of the authors except Browning and Sugarman were associated at one time or another with both institutions. The main conclusion of the research is that sea-level change was a primary driver of sedimentary cyclicity for at least the last 34 million years, with a lesser role in the substantially warmer Cretaceous and Paleogene periods. Long-term sea level peaked at 100 ± 50 m during the Cretaceous, implying that ocean-crust production rates were much lower than previously inferred. The sea-level record is less well established for Phanerozoic time before about 100 Myr ago.

Miller, K.G., Kominz, M.A., Browning, J.V., Wright, J.D., Mountain, G.S., Katz, M.E., Sugarman, P.J., Cramer, B.S., Christie-Blick, N., and Pekar, S.F., 2005, The Phanerozoic record of global sea-level change: Science, v. 310, p. 1293-1298.

20. Observations from the Basin and Range Province (western United States) pertinent to the interpretation of regional detachment faults  [download PDF 11.6 MB]

Studies over several years in three areas of the Basin and Range Province cast doubt on the interpretation of specific regional detachment faults and the large extensional strains with which such faults are commonly associated. The Sevier Desert detachment of west-central Utah is reinterpreted as an unconformity aligned down dip in some profiles with a Mesozoic thrust fault, though that view has not been generally accepted by the structural geological community (see above). The Mormon Peak detachment of southeastern Nevada is reinterpreted as the basal contact of a series of Miocene slide blocks (see Anders et al., 2006, Journal of Geology, v. 114, p. 645-664). That conclusion is also strongly disputed by those responsible for the rooted fault interpretation. Re-evaluation of middle Miocene deposits in eastern California shows that they cannot be used as a piercing point to constrain large-scale extension and displacement on detachment faults across the Death Valley region (Renik et al., 2008, Journal of Sedimentary Research, v. 78, p. 199-219).

Christie-Blick, N., Anders, M.H., Wills, S., Walker, C.D., and *Renik, B., 2007, Observations from the Basin and Range Province (western United States) pertinent to the interpretation of regional detachment faults, in Karner, G.D., Manatschal, G., and Pinheiro, L.M., eds., Imaging, Mapping and Modelling Continental Lithosphere Extension and Breakup: Geological Society of London Special Publication No. 282, p. 421-441.

21. Is there a role for sequence stratigraphy in chronostratigraphy?  [download PDF 140 KB]

Sequence stratigraphy provides a useful framework for local or regional stratigraphic interpretation. However, a lack of consensus on criteria for recognizing, mapping and hence dating sequence boundaries, interpretations of uneven quality, and doubts about the universal eustatic origin and synchrony of unconformity-related sequences limit the usefulness of sequence stratigraphy in chronostratigraphy.

Christie-Blick, N., †Pekar, S.F., and *Madof, A.S., 2007, Is there a role for sequence stratigraphy in chronostratigraphy?: Stratigraphy, v. 4, No. 2/3, p. 217-229.

22. Re-evaluation of the middle Miocene Eagle Mountain Formation, and its significance as a piercing point for the interpretation of extreme extension across the Death Valley region, California, U.S.A. [download PDF 13.5 MB]

A sedimentological and stratigraphic re-evaluation of the middle Miocene Eagle Mountain Formation at Eagle Mountain, California, indicates that deposition took place in a fluvial-lacustrine setting. The result is important because the presence of distinctive clasts as large as boulders derived from the Hunter Mountain batholith of the Cottonwood Mountains, combined with an alluvial fan interpretation for the conglomerate in which the clasts are found, has been regarded as providing definitive, independent support for long-hypothesized, large-scale crustal extension across the Death Valley region.

*Renik, B., Christie-Blick, N., Troxel, B.W., Wright, L.A., and Niemi, N.A., 2008, Re-evaluation of the middle Miocene Eagle Mountain Formation and its significance as a piercing point for the interpretation of extreme extension across the Death Valley region, California, U.S.A.: Journal of Sedimentary Research, v. 78, p. 199-219.

23. Testing the extensional detachment paradigm: A borehole observatory in the Sevier Desert basin [download PDF 880 KB]

Low-angle normal faults or detachments are widely regarded as playing an important role in crustal extension and the development of rifted continental margins. However, no consensus exists on how to resolve the mechanical paradox implied by the gentle dips of these faults and by the general absence of evidence for associated seismicity. As part of a new initiative to rationalize geological and geophysical evidence and our theoretical understanding of how rocks deform, a group of forty-seven scientists and drilling experts from five countries met for four days on 15–18 July, 2008 to discuss the present status of the paradox and a borehole-based strategy for resolving it.

Christie-Blick, N., Anders, M.H., Manatschal, G., and Wernicke, B.P., 2009, Testing the extensional detachment paradigm: A borehole observatory in the Sevier Desert basin: Scientific Drilling, No. 8, p. 57-59.

24. Stratigraphic controls on a salt-withdrawal intraslope minibasin, north-central Green Canyon, Gulf of Mexico: Implications for misinterpreting sea level change [download PDF 2.2 MB]

3D seismic reflection data show that sedimentation along the Gulf of Mexico continental margin was strongly influenced by salt tectonics, casting doubt on the role of eustasy in modulating off-shelf "lowstand" sedimentation, and more generally on the paradigm of reciprocal sedimentation.

*Madof, A.S., Christie-Blick, N., and Anders, M.H., 2009, Stratigraphic controls on a salt-withdrawal intraslope minibasin, north-central Green Canyon, Gulf of Mexico: Implications for misinterpreting sea level change: American Association of Petroleum Geologists Bulletin, v. 93, p. 535-561.

25. Terminology of geological time: Establishment of a community standard

[download PDF 288 KB]

Consistent with a convention that has been used widely since the 1970s, this paper recommends standardization of the distinction between geohistorical dates (with the symbols ‘a’ for annus, ‘ka’, ‘Ma’ and ‘Ga’ for years and thousands, millions and billions of years before present) and spans of geological time (expressed in ‘yr’, ‘kyr’, ‘Myr’ and ‘Gyr’). The manuscript was rushed into print in the fall of 2009 in an unsuccessful effort to head off the formal abandonment of this convention by the International Union of Geological Sciences (IUGS) and the International Union of Pure and Applied Chemistry (IUPAC) in favor of adopting the symbols ‘a’, ‘ka’, ‘Ma’ and ‘Ga’ for use in both senses.

Aubry, M.-P., Van Couvering, J.A., Christie-Blick, N., Landing, E., Pratt, B.R., Owen, D.E., and Ferrusquía-Villafranca, I., 2009, Terminology of geological time: Establishment of a community standard: Stratigraphy, v. 6, No. 2, p. 100-105.

26. Condensation origin for Neoproterozoic cap carbonates during deglaciation [download PDF 412 KB]

This paper evolved through multiple drafts (and rejections) since it was first conceived in 1995. The essence is very simple: Neoproterozoic cap carbonates represent very slow, and likely episodic sedimentation (over at least hundreds of thousands of years), not the geologically instantaneous event popularized by the snowball Earth hypothesis. It is possible to demonstrate in the Amadeus basin of central Australia how a classic cap carbonate no more than a few meters thick passes laterally into a 175-m-thick succession of non-marine conglomerate and sandstone representing four unconformity-bounded sequences (the Gaylad Sandstone). Over the 16 years in which the manuscript was in fitful gestation, it came to be known affectionately as the ‘laughing child’.

Kennedy, M.J., and Christie-Blick, N., 2011, Condensation origin for Neoproterozoic cap carbonates during deglaciation: Geology, v. 39, p. 319-322.

27. Neoproterozoic strata of southeastern Idaho and Utah: record of Cryogenian rifting and glaciation [download PDF 668 KB]

Thirty years after the publication of Hambrey and Harland’s massive 1981 synthesis of the pre-Pleistocene glacial record, this volume focuses on substantial progress made in understanding the Neoproterozoic part of that record. The chapter on Idaho and Utah summarizes important new U/Pb SHRIMP geochronology on detrital zircons, as well as research on non-glacial facies, stratigraphy and tectonics undertaken since the completion of our respective dissertations in 1982 and 1979.

Link, P.K., and Christie-Blick, N., 2011, Neoproterozoic strata of southeastern Idaho and Utah: record of Cryogenian rifting and glaciation, in Arnaud, E., Halverson, G.P., and Shields-Zhou, G., eds., The Geological Record of Neoproterozoic Glaciations: Geological Society, London, Memoirs, v. 36, p. 425-436.

28. Does God exist? Does it matter? [download PDF 340 KB]

This short, peer-reviewed article represents an attempt to stake out a position purposefully on a sensitive topic. After years of mulling, I have come to accept Richard Dawkins’s view: that the distinction between propositions that are testable (subject to the scientific method) and matters of faith (supposedly outside the realm of science) is at best fuzzy. Given that much of what is believed is inconsistent with science and that the rest is so fundamentally anthropocentric that it makes no sense at the length scales and timescales of the universe, as they are now understood, it seems to me not unreasonable to point that out. The manuscript was written in May-June, 2010 for Freethought Today, a monthly newspaper of the Freedom from Religion Foundation, and provisionally accepted at that time. I pulled the plug after one year when no publication date could be confirmed.

Christie-Blick, N., 2011, Does God exist? Does it matter?: American Atheist, v. 49, No. 3, p. 20-21 and 39.

Addendum: A conversation with Christian Chapman [download PDF 300 KB]

Christian Chapman is an aptly named evangelical Christian, a pastor by training, and a speaker for the Colorado-based Kingdom Building Ministries. I wrote to Christian in late December, 2011, after an article appeared in the New York Times concerning his evangelical work in public schools. This is the lightly edited text of a conversation that I had with Christian, via Facebook, from 2-13 May, 2012. The exchange illuminates how those with sufficiently deep faith justify positions that are strikingly inconsistent with what has been discovered through painstaking scientific research; and at least in part why it has proven so difficult to communicate scientific results to lay people in some parts of the United States.

29. Geological time conventions and symbols [download PDF 132 KB]

This article was written as a rebuttal of action by the International Union of Geological Sciences (IUGS) and the International Union of Pure and Applied Chemistry (IUPAC) to abandon the longstanding convention in Earth science of distinguishing between geohistorical dates and spans of geological time. The symbols a, ka, Ma, and Ga are recommended for exclusive use for points in geological time 100, 103, 106, and 109 years before present; and yr, kyr, Myr, and Gyr for geohistorical time in years duration (again adopting SI prefixes). Such usage is consistent with current practice of the American Geophysical Union, Geological Society of America, American Association of Petroleum Geologists, etc.

Christie-Blick, N., 2012, Geological time conventions and symbols: GSA Today, v. 22, no. 2, p. 28-29.

30. Cominco American well: Implications for the reconstruction of the Sevier orogen and Basin and Range extension in west-central Utah [download PDF 3.2 MB]

This paper sheds new light on the interpretation of Neoproterozoic and Cambrian stratigraphy and Mesozoic structure in a region that has been influential in the development of ideas about crustal shortening and extension. The Canyon Range thrust is shown to cut the Cominco American well at an appreciably shallower level than generally accepted (e.g., DeCelles and Coogan, 2006, Geological Society of America Bulletin, v. 118, p. 841-864; Coogan and DeCelles, 2007, Geological Society of America Bulletin, v. 119, p. 508-512), and not to provide a piercing point for the estimation of displacement on the Sevier Desert detachment or justification for the existence of the detachment.

Anders, M.H., Christie-Blick, N., and Malinverno, A., 2012, Cominco American well: Implications for the reconstruction of the Sevier orogen and Basin and Range extension in west-central Utah: American Journal of Science, v. 312, p. 508-533.

31. Do phreatomagmatic eruptions at Ubehebe Crater (Death Valley, California) relate to a wetter than present hydro-climate? [download PDF 608 KB]

The Ubehebe project was hatched during the 2008 Spring Break trip to Death Valley, in a discussion of why most eruptions at Ubehebe Crater have been phreatomagmatic – steam explosions caused by the interaction of rising magma with groundwater – in one of the most arid places on Earth. Beryllium-10 (10Be) surface exposure dating confirmed that the main and most recent period of activity was between 0.8 and 2.1 ka, a span that encompassed an interval of prolonged drought in the American southwest (the Medieval Warm Period). We conclude on that basis that sufficient groundwater was generally available at the Ubehebe site to trigger phreatomagmatic eruptions, in spite of the prevailing arid conditions. Peri Sasnett prepared the samples during a summer internship at Lamont in 2009, and used the results for her 2011 senior thesis.

https://news.agu.org/press-release/waiting-for-death-valleys-big-bang-a-volcanic-explosion-crater-may-have-future-potential/

Sasnett, P., Goehring, B.M., Christie-Blick, N., and Schaefer, J.M., 2012, Do phreatomagmatic eruptions at Ubehebe Crater (Death Valley, California) relate to a wetter than present hydro-climate?: Geophysical Research Letters, v. 39, L02401, doi:10.1029/2011GL050130.

32. A new hypothesis for the amount and distribution of dextral displacement along the Fish Lake Valley-northern Death Valley-Furnace Creek fault zone, California-Nevada [download PDF 5.5 MB]

The Fish Lake Valley–northern Death Valley–Furnace Creek strike-slip fault zone is the easternmost active element of the San Andreas transform plate boundary, and it provides a key constraint for tectonic reconstructions of the Death Valley area and the central Basin and Range Province. The main contribution of this paper is to show that offset since 13-10 million years ago was no more than ~50 km. This is appreciably less than estimates as high as 80 km obtained by previous authors. Among implications of our result: the increase in line length across Death Valley between points in what are now the Cottonwood Mountains and Nopah Range, and through a combination of extension and strike slip, has been overestimated by a factor of 50%. Displacement along and tilting of discrete normal faults is sufficient to account for the inferred extension. Mechanically problematic mechanisms such as regional-scale detachment faulting and the rolling hinge model aren’t required.

*Renik, B., and Christie-Blick, N., 2013, A new hypothesis for the amount and distribution of dextral displacement along the Fish Lake Valley-northern Death Valley-Furnace Creek fault zone, California-Nevada: Tectonics, v. 32, p. 123-145, doi:10.1029/2012TC003170.

33. Tectonically controlled nearshore deposition: Cozzette Sandstone, Book Cliffs, Colorado, U.S.A. [download PDF 10.4 MB]

Eustasy remains the generally accepted explanation for sedimentary cyclicity at timescales of < 1 Myr even in tectonically active settings such as the Cretaceous interior seaway (a foreland basin). This paper challenges that view by using a combination of outcrop and downhole log data from 294 gas wells to demonstrate a key role in this basin for brittle deformation and three-dimensional tectonic tilting at length scales of up to 50 km and timescales of ~200 kyr. An innovation in the reported research was to make use of a set of overlapping photographs acquired by helicopter for the entire 40 km panel of the Book Cliffs encompassed by our study. Those photographs and subsurface constraints were critical in establishing subtle stratal geometry (e.g., offlap at parasequence scale) that may be generally present but commonly missed in conventional outcrop work.

*Madof, A.S., Christie-Blick, N., and Anders, M.H., 2015, Tectonically controlled nearshore deposition: Cozzette Sandstone, Book Cliffs, Colorado, U.S.A.: Journal of Sedimentary Research, v. 85, p. 459-488, doi:10.2110/jsr.2015.26.

34. Reexamination of the crustal boundary context of Mesoproterozoic granites in southern Nevada using U-Pb zircon chronology and Nd and Pb isotopic compositions [download PDF 2.1 MB]

New dating of Rapakivi or A-type granites in southern Nevada yields a surprising result: none of the granites we sampled from the supposedly widespread 1,400-1,450 Ma suite is of that age. Most samples cluster in age around 1,680 Ma. One sample, from Gold Butte, Nevada, yielded an age of 1,373 ± 6 Ma. Previously inconsistent mapping of isotopic crustal boundaries is refined and rationalized in the context of the new geochronology to accommodate new and published Nd and Pb isotopic data.

*Almeida, R.V., Cai, Y., Hemming, S.R., Christie-Blick, N., and Neiswanger, L.S., 2016, Reexamination of the crustal boundary context of Mesoproterozoic granites in southern Nevada using U-Pb zircon chronology and Nd and Pb isotopic compositions: Journal of Geology, v. 124, p. 313-329, doi:10.1086/685766.

35. Unreciprocated sedimentation along a mud-dominated continental margin, Gulf of Mexico, U.S.A.: Implications for sequence stratigraphy in muddy settings devoid of depositional sequences [download PDF 16.5 MB]

According to widely accepted sequence stratigraphic and fill-and-spill models, sedimentary cyclicity at continental margins is modulated by a combination of sea-level change and the filling of pre-existing bathymetric depressions. New work in the Pliocene to Holocene of offshore Louisiana suggests that the distribution of facies, timing and location of mass transport deposits, and rates of sediment accumulation are controlled instead by salt-related subsidence.

*Madof, A.S., Christie-Blick, N., Anders, M.H., and Febo, L.A., 2017, Unreciprocated sedimentation along a mud-dominated continental margin, Gulf of Mexico, U.S.A.: Implications for sequence stratigraphy in muddy settings devoid of depositional sequences: Marine and Petroleum Geology, v. 80, p. 492-516, doi:10.1016/j.marpetgeo.2016.12.022.