A critical review of the case for, and against, extraterrestrial impact at the K/T boundary

Alexopoulos, J. S., Grieve, R. A. F., and Robertson, P. B.: 1988, ‘Microscopic Lamellar Deformation Features in Quartz: Discriminative Characteristics of Shocks-generated Varietiers’,Geology 16, 796–799. Alvarez, W.: 1986, ‘Toward a Theory of Impact Crises,’EOS 67, 649. Alvarez, L. W., Alvarez, W., Asaro, F., and Michel, H. V.: 1980, ‘Extraterrestrial Cause of the Cretaceous-Tertiary Extinction,’Science 208, 1095–1108. Alvarez, W., Alvarez, L. W., Asaro, F., and Michel, H. V.: 1982, ‘Current Status of the Impact Theory for the Terminal Cretaceous Extinction,’ Geological Society of America Special Paper 190, 305–315. Alvarez, W., Alvarez, L. W., Asaro, F., and Michel, H. V.: 1984, ‘The End of the Cretaceous: Sharp Boundary or Gradual Transition?’,Science 223, 1183–1186. Alvarez, W., Kauffman, E. G., Surlyk, F., Alvarez, L. W., Asaro, F., and Michel, H. V.: 1984, Impact Theory of Mass Extinctions and the Invertebrane Fossil Record,Science 223, 1135–1141. Anders, E. and Ebihara, M.: 1982, ‘Solar-system Abundances of Elements,’Geochimica et Cosmochimica Acta 46, 2363–2380. Archibald, J. D., Butler, R. F., Lindsay, E. H., Clemens, W. A., and Dingus, L.: 1982, ‘Upper Cretaceous-Paleocene Biostratigraphy and Magnetostratigraphy, Hell Creekand Tullock Formations, Northeastern Montana’,Geology 10, 153–159. Archibald, J. D. and Clemens, W. A.: 1984, ‘Mammal Evolution near the Cretaceous-Tertiary Boundary’, in W. A. Berggren and J. A. van Couvering (eds.),Catastrophes in Earth History, Princeton University Press, Princeton, 339–371. Arthur, M. A., Dean, W. E., and Schlanger, S. O.: 1985, ‘Variations in the Global Carbon Cycle During the Cretaceous Related to Climate, Volcanism, and Changes in Atmospheric CO2’ in, E. T. Sundquist, and W. S. Broecker (eds.),The Carbon Cycle and Atmospheric CO 2:Natural Variations Archaen to Present, American Geophysical Union, Washington, 504–529. Arthur, M. A., Dean, W. E., and Pratt, L. M.: 1988: ‘Geochemical and Climatic Effects of Increased Marine Organic Carbon Burial at the Cenomanian/Turonian Boundary’,Nature 335, 714–717. Asaro, F., Michel, H. V., Alvarez, L. W., and Alvarez, W. 1982: ‘Results of a Dating Attempt: Chemical and Physical Measurement Relevant to the Cause of the Cretaceous-Tertiary Extinction’,American Chemical Society Symposium Series 176, 401–409. Askin, R. A.: 1988, ‘The Palynological Record across the Cretaceous/Tertiary Transition on Seymour Island, Antartica’,Geological Society of America, Memoir 169, 156–162. Baadsgaard, H., Lerbekmo, J. F., and McDougall, I.: 1988, ‘A Radiometric Age for the Cretaceous-Tertiary Boundary Based upon K−Ar, Rb−Sr, and U−Pb Ages of Bentonites from Alberta, Saskatchewan, and Montana’,Canadian Journal of Earth Sciences 25, 1088–1097. Badjukov, D. D., Nazarov, M. A., and Alekseev, A. S.: 1987, ‘The K/T Event: Amount of the Crater Ejecta and the Possible Impact Site’ (abs.), Lunar and Planetary Science, 18, Lunar and Planetary Institute, Houston, 40–41. Barker, J. L. and Anders, E.: 1968: ‘Accretion Rate of Cosmic Matter from Iridium and Osmium Contents of Deep-see Sediments’,Geochimica et Cosmochimica Acta 32, 627–645. Barrera, E., Huber, B. T., Savin, S. M., and Webb, P-N.: 1987, ‘Antarctic Marine Temperatures Late Campian through Early Paleocene’,Paleoceanography 2, 21–47. Batten, D. J.: 1981, ‘Stratigraphic, Palaeographic and Evolutionary Significance of Late Cretaceous and Early Tertiary Normapolles Pollen’,Review of Palaeobotony and Palynology 35, 125–137. Bentor, Y. K.: 1986, ‘A New Approchs to the Problem of Tektite Genesis’,Earth Planetary Science Letters 77, 1–13. Betzer, P. R. and others: 1988, ‘Long-range Transport of Mineral Aerosol Particles’,Nature 336, 568–571. Bhandari, N., Gupta, M., Pandey, J., and Shulka, P. N.: 1988. ‘Geochemistry of K/T Boundaries in India and Contributions of Deccan Volcanism’ (abs.), in Global Catastrophies in Earth History: An Interdisciplinary Conference on Impacts, Volcanism, and Mass Mortality’, Lunar And Planetary Institute, Houston, 15–16. Bohor, B. F.: 1988, ‘Shocked Quartz and More: Impact Signatures in K/T Boundary Clays and Claystones’ (abs.),ibid., India and Contributions of Deccan Volcanism’ (abs.), in Global Catastrophies in Earth History: An Interdisciplinary Conference on Impacts, Volcanism, and Mass Mortality’, Lunar And Planetary Institute, Houston, 17–18. Bohor, B. F. and Izett, G. A.: 1986, ‘Worldwide Size Distribution of Shocked Quartz at the K/T Boundary: Evidence for a North American Impact Site’, Lunar and Planetary Science 17, Lunar and Planetary Institute, Houston, 68–69. Bohor, B. F. and Foord, E. E.: 1987, ‘Magnesioferrite from a Nonmarine K-T Boundary Clay in Wyoing’ (abs.), Lunar and Planetary Sciences18, Lunar and Planetary Institute, Houston, 101–102. Bohor, B. F. and Triplehorn, D. M.: 1987, ‘Flaysh: An Analog for Spherules in K-T Boundary Clays’ (abs.), Lunar and Planetary Science18, Lunar and Planetary Institute, Houston, 103–104> Bohor, B. F., Foord, E. E., Modreski, P. J., and Triplehorn, D. M.: 1984, ‘Mineralogic Evidence for an Impact Event at the Cretaceous-Tertiary Boundary’,Sciences 224, 867–869. Bohor, B. F., Foord, E. E., and Ganapathy, R.: 1986, ‘Magnesioferrite from the Cretaceous-Teriary Boundary, Carvaca Spain’,Earth and Planetary Science Letters 81, 57–66. Bohor, B. F., Modreski, P. J. and Foord, E. E.: 1987a, ‘Shocked Quartz in the Cretaceous-Tertiary Boundary Clays: Evidence for a Global Distribution’,Science 236, 705–710. Bohor, B. F., Triplehorn, D. M., Nichols, D. J., and Millard, H. T., Jr.: 1987b, ‘Dinosaurs, Spherules, and the “Magic” Layer: a New K-T Boundary Clay Site in Wyoming’,Geology 15, 896–899. Bohor, B. F., Betterton, W. J., and Foord, E. E.: 1988, ‘Coesite, Glass, and Shocked Quartz at DSDP Site 612’ (abs.), Lunar and Planetary Science 19, Lunar and Planetary Institute, Houston, 114–115. Borella, P. E.: 1984, ‘Sedimentology, Petrology, and Cyclic Sedimentation Pantterns, Walvis Ridge Transect, Leg 74, Deep Sea Drilling Project’,DSDP Initial Reports 74, 645–662. Bott, M. H. P.: 1988, ‘A New Look at the Causes and Consequences of the Icelandic Host-spot’,Geological Society Special Publication 39, 15–23. Bottomley, R. and York, D.: 1988, ‘Age Measurement of the Submarine Montagnais Impact Crater’,Geophysical Research Letters 15, 1409–1412. Bourgeois, J., Hansen, T. A., Wiberg, P. L., and Kaufmann, E. G.: 1988, ‘A Tsunami Deposit at the Cretaceous-Tertiary Boundary in Texas’,Science 241, 567–570. Brett, R.: 1967, ‘Metallic Spherules in Impactite and Tektite Glass’,American Mineralogist 52, 721–733. Brooks, M.: 1973, ‘Some Aspects of the Paleogene Evolution of Western Britain in the Context of an Underlying Mantle Hot Spot’,Journal of Geology 81, 81–88. Brooks, R. B., Reeves, R. D., Xing-Hua Yang, Ryan, D. E., Holzbecher, J., Collen, J. D., Neall, V. E., and Lee, J.: 1984, ‘Weathered Spheroids in a Cretaceous/Tertiary Boundary Shale at Woodside Creek, New Zealand’,Science 226, 539–542. Butler, R. F. and Lindsay, E. H.: 1985, Mineralogy of Magnetic Minerals and Revised Magnetic Polarity Stratigraphy of Continental Sediments, San Juan Basin, New Mexico,Journal of Geology 93, 535–554. Butler, R. F., Gingerich, P. D., and Lindsay, E. H.: 1981, ‘Magnetic Polarity Straigraphy and Biostratigraphy of Paleocene and Lower Eocene Continetal Deposits, Clark's Fork Basin, Wyoming’,Journal of Geology 89, 299–316. Byers, P. N.: 1969, ‘Mineralogy and Origin of the Upper Eastend and Whitemud Formations of Southcentral and Southwestern Saskatchewan and Southeastern Alberta’,Canadian Journal of Earth Sciences 6, 317–334. Carter, N. L., Officer, C. B., Chesner, C. A., and Rose, W. I.: 1986, ‘Dynamic Deformation of Volcanic Ejecta from the Toba Caldera: Possible Relevance to Cretaceous/Tecrtiary Boundary Phenomena’,Geogy 14, 380–383. Carter, N. L., Officer, C. B., and Drake, C. L.: 1990, ‘Dynamic Deformation of Quartz and Feldspar: Clues to Causes of Some Natural Crises,’Tectonophysics (in press): Chamley, H., Maillot, H., Duee, G., and Robert, C., 1984, ‘Paleoenvironmental History of the Walvis Ridge at the Cretaceous-Tertiary Transition, from Mineralogical and Geochemical Investigations’,DSDP Inital Report 74, 685–695. Cisowski, S. M.: 1988a, ‘Magnetic Properties of K/T and E/O Microspherule: Origin by Combustion’,Earth and Planetary Science Letters 88, 193–208. Cisowski, S. M.: 1988b, ‘Analogues for Magnetic Microspherules Associated with the K/T and Upper Eocene Extinction Events’ (abs.), Lunar and Planetary Science 19, Lunar and Planetary Institute, Houston, 186–187. Cisowski, S. M.: 1988c, ‘Paleomagnetism of Manson Structure Cores Inconsistent with a K/T Link’ (abs), Lunar and Planetary Science 19, Lunar and Planetary Institute, Houston, 188–189. Clark, D. L. and Byers, C. W.: 1986, ‘Cretaceous Black Mud from the Central Arctic Ocean’,Paleooceanography 1, 265–271. Clarke, D. B.: 1970, ‘Tertiary basalts of Baffin Bay: possible primary magma from the mantle’,Contributions to Mineralogy and Petrology 25, 203–224. Clarke, D. B. and Pedersen, A. K.: 1976, ‘Tertiary Volcanic Province of West Greenland’, in A. Escher and W. S. Watt (eds.),Geology of Greenland, The Geological Survey of Greenland, 366–385. Clarke, D. B. and Upton, B. G. J.: 1971, ‘Tertiary Basalts of Baffin Island: Field Relations and Tectonic Setting’,Canadian Journal of Earth Science 8, 248–258. Courtillot, V. E. and Cisowski, S. M.: 1987, ‘The Cretaceous-Tertiary Boundary Events: External or Internal Causes?’,EOS 68, 193,200. Courtillot, V., Besse, J., Vandamme, D., Montigny, R., Jaeger, J-J., and Cappetta, H.: 1986, ‘Deccan Flood Basalts at the Cretaceous/Tertiary Boundary?’,Earth Planetary Science Letters 80, 361–374. Courtillot, V., Vandamme, D., and Besse, J.: 1987, ‘Reply to Comments on “Deccan Flood Basalts at the Cretaceous/Tertiary Boundary?” by H. Wensink,Earth and Planetary Science Letters 86, 122–123. Courtillot, V., Feraud, G., Maluski, H., Vandamme, D., Moreau, M. G., and Besse, J.: 1988, ‘Deccan Flood Basalts and the Cretaceous/Tertiary Boundary’,Nature 333, 843–846. Crawford, A. R.: 1963, ‘Large Ring Structures in a South Australian Precambrian Volcanic Complex’,Nature 197, 140–142. Crocket, J. H., Officer, C. B., Wezel, and Johnson, G. D.: 1988, ‘Distribution of Noble Metals across the Cretaceous/Tertiary Boundary at Gubbio, Italy: Iridium Variation as a Constrain on the Duration and Nature of Cretaceous/Tertiary Boundary Events’,Geology 16, 77–80. Croxton, C. A.: 1980, ‘Aquilapollenites from the Late Cretaceous-Paleocene (?) of Central West Greenland’,Rapports Gronlands Geologiske Undersogelse 101, 5–27. DePaolo, D. J., Kyte, F. T., Marshall, B. D., O'Neil and Smit, J.: 1983, ‘Rb−Sr, Sm−Nd, K−Ca, O and H Isotopic Study of Cretaceous-Tertiary Boundary Sediments, Carvaca, Spain: Evidence for an Oceanic Impact Site’,Earth and Planetary Science Letters 64, 356–373. De Laubenfels, M. W.: 1956, ‘Dinosaur Extinction: One More Hypothesis’,Journal of Paleontology 30, 207–218. Dickinson, R. G., Leopold, E. B. and Marvin, R. F.: 1968, ‘Late Cretaceous Uplift and Volcanism on the North Flank of the San Juan Mountains, Colorado’,Quarterly of the Colorado School of Mines 63, 125–148. Doehne, E. and Margolis, S. V.: 1989, ‘Platinum and Nickel-Rich Mineral Phases from the Cretaceous-Tertiary Boundary Sediments at Zumaya, Spain’, Proceedings of the Conference on Global Catastrophes in Earth History (in press). Donovan, A. D. and Vail, P. R.: 1986, ‘Sequence Stratigraphy of the K−T Boundary in Alabama: a Noncatastrophic Alternative’ (abs.), Geological Society of America Annual Meeting, 587. Draper, R. B.: 1935, ‘The Synthesis of Magnesioferrite and Some Observations on “Mineralization”’,American Journal of Science 30, 106–115. Duncan, R. A. and Pyle, D. G.: 1988, ‘Rapid Eruption of the Deccan Flood Basalts at the Cretaceous/Tertiary Boundary’,Nature 333, 841–843. Elliot, W. C., Aronson, J. L., Millard, H. T. and Gierlowski-Kordesch, E.: 1989, ‘The Origin of the Clay Minerals at the Cretaceous/Tertiary Boundary in Denmark’,Geological Societ of America Bulletin 101, 702–710. Emiliani, C., Kraus, E. B., and Shoemaker, E. M.: 1981, ‘Sudden Death at the End of the Mesozoic’,Earth and Planetary Science Letters 55, 317–334. Eugster, O., Geiss, J., and Krahenbuhl, U.: 1985, ‘Noble Gas Isotopic Abundances and Noble Metal Concentrations in Sediments from the Cretaceous-Tertiary Boundary’,Earth and Planetary Science Letters 74, 27–34. Evans, A. L., Fitsch F. J., and Miller, J. A.: 1973, ‘Potassium-argon Age Determinations on Some British Tertiary Igneous Rocks’,Journal of the Geological Society of London 129, 419–443. Ezeji-Okoye, S.: 1986, The Origin of the Eagle Butte Structure, Pan Canadian Petroleum Limited, internal report, Calgary, 75 pp. Gallet, Y., Weeks, R., Vandamme, D., and Courtillot, V.: 1989, ‘Duration of Deccan Trap Volcanism: A Statistical Approach’,Earth and Planetary Science Letters 93, 273–282. Ganapathy, R.: 1980, ‘Major Meteorite Impact on the Earth 65 Million Years Ago: Evidence from the Cretaceous-Tertiary Boundary Clay’,Science 209, 921–923. Ganapathy, R. andLarimer, J. W.:1983, ‘Nickel-iron Spherules in Tektites: Non-meteoritic in Origin’,Earth and Planetary Science Letters 65, 225–228. Gerstel, J., Thunnel, R. C., Zachos, J. C., and Arthur, M. A.: 1986, The Cretaceous/Tertiary Boundary Event in the North Pacific: Planktonic Foraminiferal Results from Deep Sea Drilling Project Site 577, Shatsky Rise’,Paleooceanography 1, 97–117. Gijbels, R., Henderson, P., and Zels, J.: 1976, ‘Geochemistry of Some Trace Elements in Mineral Seperates from Rhum, Inner Hebrides, with Special Emphasis on Iridium,”Economic Geology 71, 1364–1370. Gilmore, J. S., Knight, J. D., Orth, C. J., Pillmore, C. L., and Tschudy, R. H.: 1984, ‘Trace Element Patterns at a Nonmarine Cretaceous-Tertiary Boundary, Western Interior’,Nature 307, 224–228. Gilmour, I. and Anders, E., 1989, ‘Cretaceous-Tertiary Boundary Event: Evidence for a Short Time Scale’,Geochemica et Cosmochimica Acta 53, 503–511. Gilmour, I. and Guenther, F.: 1988, ‘The Global Cretaceous-Tertiary Fire: Biomass or Fossil Carbon?’ (abs.), in Global Catastrophes in Earth History: an Interdisciplinary Conference on Impacts Volcanism, and Mass Mortality, Lunar and Planetary Institute, Houston, 60–61. Glass, B. P., Burns, C. A., Crosbie, J. R., and DuBois, D. L.: 1985, ‘Late Eocene North American Microtektites and Clinopyroxene-bearing Spherules’, Proceedings of the 16th Lunar Planetary Science Conference, D175–D196. Gostin, V. A., Keays, R. R., and Wallace, M. W.: 1989, ‘Iridium Anomaly from the Acraman Impact Ejecta Horizon: Impacts Can Produce Sedimentary Iridium Peaks’Nature 340, 542–544. Gottfried, D. and Greenland, L. P.: 1972, ‘Variation of Iridium and Gold in Oceanic and Continental Basalts’,International Geological Congress 24th 10, 135–144. Graup, G.: 1988, ‘Mineralogy and Phase-chemistry of the Cretaceous/Tertiary Section in the Lattengebirge, Bavarian Alps’, (abs.), inGlobal Catastrophes in Earth History: An Interdisciplinary Conference on Impacts, Volcanism, and Mass Mortality, Lunar and Planetary Institute, Houston, 65. Grieve, R. A. F. and Alexopoulos, J.: 1988, ‘Microscopic Planar Features in Quartz from Scollard Canyon, Alberta, and the Cretaceous-Tertiary Boundary Event’,Canadian Journal of Earth Sciences 25, 1530–1534. Grieve, R. A. F., and Sharpton, V. L.: 1986, ‘The K/T Impact Event: Some Implications from the Evidence’ (abs.), Lunar and Planetary Science17, Lunar and Planetary Institute, Houston, 289–290. Gross, S.: 1977, ‘The Mineralogy of the Hatrurim Formation,Israel Geological Survey of Israel Bulletin 70, 8–9. Hald, N. and Larsen, J. G.: 1987, ‘Early Tertiary, Low-potassium Tholeiites from Exploration Wells on the West Greenland Shelf’, Gronlands Geologiske Undersogelse 136. Hald, N. and Pedersen, A. K.: 1975, ‘Lithostratigraphy of the Early Tertiary Volcanic Rocks of Central West Greenland’,Rapports Gronlands Geologiske Undersogelse 69, 17–24. Hallam, A.: 1987, ‘End-Cretaceous Mass Extinction Event: Argument for Terrestrial Causation,’Science 238, 1237–1242. Hansen, H. J.: 1988, ‘Diachronism between Extinction Time of Terrestrial and Marine Dinosaurs (abs.)’, in Global Catastrphies in Earth History: An Interdisciplinary Conference on Impacts, Volcanism, and Mass Mortality, Lunar and Planetary Institute, Houston, 68–69. Hansen, H. J., Gwozdz, R., Bromley, R. G., Rasmussen, K. L., Vogensen, E. W., and Pedersen, K. R.: 1986. ‘Cretaceous-Tertiary Boundary Spherules from Denmark, New Zealand and Spain,’,Bulletin of the Geological Society of Denmark 35, 75–82. Hansen, H. J., Rasmussen, K. L., Gwozdz, R., and Kunzendorf, H.: 1987, ‘Iridium-bearing C Carbon Black at the Cretaceous-Tertiary Boundary’,Bulletin of the Geological Society of Denmark 36, 305–314. Hansen, H. J., Gwozdz, R., and Rasmussen, K. L.: 1988, ‘High-resolution Trace Element Chemistry across the Cretaceous-Tertiary Boundary in Denmark’,.Journal Espanola de Paleontologia (in press). Haq, U. H., Hardenbol, J., and Vail, P. R.: 1987, ‘Chronology of Fluctuating Sea Levels since the Triassic’,Science 235, 1156–1167. Harriss, R. C., Crocket, J. H., and Stainton, M.: 1973, ‘Palladium, Iridium and Gold in Deep-sea Manganese Nodules,’Geochimica et, Cosmochimica Acta 32, 1049–1056. Hartnady, C. J. H.: 1986, ‘Amirante Basin, Western Indian Ocean: Possible Impact Site of the Cretaceous/Tertiary Bolide’,Geology 14, 423–426. Heissin, K.: 1986, ‘No Effect of the Ries Impact Event on the Local Mammal Fauna’,Modern Geology 10, 171–179. Hertogen, J., Janssens, M.-J., and Palme, H.: 1980, ‘Trace Elements in Ocean Ridge Basalt Glasses: Implications for Fractionations during Mantle Evolution and Petrogenesis’,Geochimica et Cosmochimica Acta 44, 2125–2143. Herring, J. R.: 1985, ‘Charcoal Fluxes into Sedidments of the North Pacific Ocean: the Cenozoic Record of Burning,’ in E. T. Sundquist and W. S. Broecker,The Carbon Cycle and Atmospheric CO 2:Natural Variations Archean to Present, American Geophysical Union, Washington, 419–442. Hickey, L. J.: 1984, ‘Changes in the Angiosperm Flora across the Cretaceous-Tertiary Boundary’, in W. A. Berggren and J. A. Van Couvering,Catastrophes and Earth History, Princeton University Press, Princeton, 279–313. Hildebrand, A. R., Boynton, W. V., and Zoller, W. H.: 1984, ‘Kilauea Volcano Aerosols: Evidence in Siderophile Element Abundances for Impact-induced Oceanic Volcanism at the K/T Boundary’ (abs.),Meteoritics 19, 239. Hildebrand, A. R. and Boynton, W. V.: 1988a, ‘Provenance of the K/T Boundary Layers’ (abs.), Global Catastrophies in Earth History: An Interdisciplinary Conference on Impacts, Volcanism, and Mass Mortality, Lunar and Planetary Institute, Houston, 78–79. Hildebrand, A. R. and Boynton, W. V.: 1988b, ‘Impact Wave Deposits Provide a New Constraint on the Location of the K/T Boundary Impact’ (abs.),ibid., 76–77. Hinz, K.: 1981, ‘A Hypothesis on Terrestrial Catastrophies, Wedges of Very Thick Oceanward Dipping Layers beneath Passive Continental Margins’,Geologische Jahrbuch 22, 3–28. Hsu, K. J.: 1980, ‘Terrestrial Catastrophe Caused by Cometary Impact at the End of the Cretaceous,’Nature 285, 201–203. Hsu, K. J.: 1982, in D. A. Russell and G. Rice (eds.),Cretaceous-Tertiary Extinctions and Possible Terrestrial and Extraterrestrial Causes, Syllogeus 39, National Museum of Natural Sciences, Ottawa. Hsu, K. J., and others: 1982, ‘Mass Mortality and its Environmental and Evolutionary Consequences,’Science 216, 249–256. Huffman, A. R., Crocket, J. H., and Carter, N. L.: 1988, ‘Iridium, Shocked Minerals, and Trace Elements across the Cretaceous/Tertiary Boundary at Maud Rise, Weddell Sea, and Walvis Ridge, South Atlantic Ocean’ (abs.), inGlobal Catastrophes in Earth History: an Interdisciplinary Conference on Impacts, Volcanism and Mass Mortality Lunar and Planetary Institute, Houston, 81–82. Hut, P., Alvarez, W., Elder, W. P., Hansen, T., Kauffman, E. G., Keller, G., Shoemaker, E. G., and Weissman, P. R.: 1987, ‘Comet Showers as a Cause, of Mass Extinctions’Nature 329, 118–126. Hyndman, R. D.: 1973, ‘Evolution of the Labrador Sea’,Canadian Journal of Earth Sciences 10, 637–644. Irvine, T. N.: 1965, ‘Chromian Spinel as a Petrogenetic Indicator’,Canadian Journal of Earth Sciences 2, 648–672. Izett, G. A.: 1987a, ‘Authigenic “Spherules” in K-T Boundary Sediments at Carvaca, Spain, and Raton Basin, Colorado and New Mexico, may Not be Impact Derived’,Geological Society of America Bulletin 99, 78–86. Izett, G. A.: 1987b, ‘The Cretaceous-Tertiary (K-T) Boundary Interval, Raton Basin, Colorado and New Mexico, and its Content of Shock-Metamorphosed Minerals: Implications Concerning the K-T Boundary Impact-Extinction Theory’, U.S. Geological Survey Open-File Report 87-606, 125 pp. Jagoutz, E., Palme, H., Baddenhausen, H., Blum, K., Cendales, M., Dreibus, G., Spettel, B., Lorenz, V., and Wanke, H.: 1979, ‘The Abundance of Major, Minor and Trace Elements in the Earth's Mantle as Derived from Primitive Ultramafic Nodules’, Proceedings of the 10th Lunar Planetary Science Conference, 2031–2050. Jamieson, B. G. and Clarke, D. B.: 1970, ‘Potassium and Associated Elements in Tholeitic Basalts’, Journal of Petrology 11, 183–204. Janssens, M-J., Hertofen, J., Takahashi, H., and Anders, E.: 1977, ‘Rochechouart Meteorite Crater: Identification of Projectile’,Journal of Geophysical Research 82, 750–758. Jerzykiewicz, T. and Sweet, A. R.: 1986, ‘The Cretaceous-Tertiary Boundary in the Central Alberta Foothills. I: Stratigraphy’Canadian Journal of Earth Sciences 23, 1356–1374. Jiang, M. J. and Gartner, S.: 1986, ‘Calcareous Nannofossil Succession across the Cretaceous/Tertiary Boundary in East-central Texas’,Micropaleontology 32, 232–255. John, C. and Glass, B. P.: 1974, ‘Clinopyroxene-bearing Glass Spherules Associated with North American Microtektites’,Geology 2, 599–602. Johnson, K. R. and Hickey, L. J.: 1988, ‘Patterns of Megafloral Change across the Cretaceous-Tertiary Boundary in the Northern Great Plains and Rocky Mountains’, inGlobal Catastrophes in Earth History: An Interdisciplinary Conference on Impacts, Volcanism, and Mass Mortality, Lunar and Planetary Institute, Houston, 87. Johnsson, M. J. and Reynolds, R. C.: 1986, ‘Clay Mineralogy of Shale-limestone Rhythmites in the Scaglia Rossa (Turonian-Euocene), Italian Apennines’,Journal of Sedimentary Petrology 56, 501–509. Jones, D. S., Mueller, P. A., Bryan, J. R., Dobson, J. P., Channell, J. E. T., Zachos, J. C., and Arthur, M. A.: 1987, ‘Biotic, Geochemical, and Paleomagnetic Changes across the Cretaceous/Tertiary Boundary at Braggs, Alabama’,Geology 15, 311–315. Jones, E. J. W., Ramsay, A. T. S., Preston, N. J., and Smith, A. C. S.: 1974, ‘A Cretaceous Guyot in the Rockall Trough’,Nature 251, 129–131. Jurgensen, T. and Mikkelsen, N.: 1974, ‘Coccoliths from Volcanic Sediments (Danian) in Nugssuaq, West Greenland,’Bulletin of the Geological Society of Denmark 23, 225–231. Kastner, M., Asaro, F., Michel, H. V., Alvarez, W., and Alvarez, L. W.: 1984, ‘The Precursor of the Cretaceous-Tertiary Boundary Clays at Stevns Klint Denmark, and DSDP Hole 465A’,Science 226, 137–143. Keith, M. L.: 1982, ‘Violent Volcanism, Stagnant Oceans and Some Inferences Regarding Petroleum, Strat-bound Ores and Mass Extinctions’,Geochimica Cosmochimica Acta 46, 2621–2637. Keller, G.: 1988, ‘Extinction, Survivorship and Evolution of Planktic Foraminifera across the Cretaceous/Tertiary Boundary at El Kef, Tunisia’,Marine Micropaleontology 13, 239–263. Kennett, J. P. and others: 1985, ‘Palaeotectonic Implications of Increased Late Ecocene-Early Oligocene Volcanism from South Pacific DSDP Sites,’,Nature 316, 1–5. Kent, D. V.: 1977, ‘An Estimate of the Duration of the Faunal Change at the Cretaceous-Tertiary Boundary,”Geology 5, 769–771. Kieffer, S. W.: 1971, ‘Shock Metamorphism of the Coconino Sandstone at Meteor Crater, Arizona’,Journal of Geophysical Research 76, 5449–5473. Klöck, W., Palme, H., and Tobschall, H. J.: 1984, ‘Trace Elements in Native Iron from Disko Island, West Greenland’ (abs),Meteoritics 19, 252–253. Koeberl, C.: 1989, ‘Iridium Enrichment in Volcanic Dust from the Blue Ice Fields, Antarctica, and Possible Relevance to the K/T Boundary Event’,Earth and Planetary Science Letters 92, 317–322. Koeberl, C., Nazarov, M. A., Harrison, T. M., Sharpton, V. L., Murali, A. V., and Burke, K.: 1988, ‘The Kara and Ust-Kara Impact Structures (USSR) and Their Relevance to the K/T Boundary Event’ (abs.),ibid., 95–96. Krähenbühl, U.: 1984, ‘Spuren von Asteroideneinschlagen auf der Erde. Neue Erkenntnisse aus chemischen Analysen alter Sedimentgeteine’,Chimia 38, 107–113. Krishnamurthy, P. and Cox, K. G.: 1977, ‘Picrite Basalts and Related Lavas from the Deccan Traps of Western India’,Contributions to Mineralogy and Petrology 62, 53–75. Kucha, H.: 1981, ‘Precious Metal Alloys and Organic Matter in the Zechstein Copper Deposits, Poland’,TMPM Tschermaks Mineralogische und Petrographische Mitteilungen 28, 1–16. Kunk, M., Izett, G. A., Haugerud, R. A., and Sutter, J. F.: 1989 ‘40Ar−39Ar Dating of the Manson Impact Structure: A Cretaceous-Tertiary Boundary Crater Candidate’,Science 244, 1565–1568. Kyte, F. T.: 1982, ‘Extraterrestrial Siderophiles in Abyssal Sediments’ (abs.),Meteoritics 17, 345. Kyte, F. T. and Brownlee, D. E.: 1985, ‘Unmelted Meteoritic Debris in the Late Pliocene Iridium Anomaly: Evidence for the Ocean Impact of a Nonchondritic Asteroid’,Geochimica et Cosmochimica Acta 49, 1095–1108. Kyte, F. T. and Smit, J.: 1986, ‘Regional Variations in Spinel Composition: an Important Key to the Cretaceous/Tertiary Event’,Geology 14, 485–487. Kyte, F. T. and Wasson, J. T.: 1982, ‘Geochemical Constraints on the Nature of Large Accretionary Events’,Geological Society of America Special Paper 190, 235–242. Kyte, F. T. and Wasson, J. T.: 1986, ‘Accretion Rate of Extraterrestrial Matter: Iridium Deposited 33 to 76 Million Years Ago’,Science 232, 1225–1229. Kyte, F. T., Zhou, Z., and Wasson, J. T.: 1980, ‘Siderophile-enriched Sediments from the Cretaceous-Tertiary Boundary’,Nature 288, 651–656. Kyte, F. T., Smit, J., and Wasson, J. T.: 1985, ‘Siderophile Interelement Variations in the Cretaceous-Tertiary Boundary Sediments from Carvaca, Spain’,Earth and Planetary Science Letters 73, 183–195. Lanphere, M. A. and Jones, D. L.: 1978, ‘Cretaceous Time Scale for North America’,Studies in Geology 6, 259–268. Larsen, O.: 1982, ‘The Age of the Kap Washington Group Volcanics, North Greenland’,Bulletin of the Geological Society of Denmark 31, 49–55. Lauf, R. J.: 1981, ‘Cenospheres in Fly Ash and Conditions Leading to their Formation’,Fuel 60, 1177–1179. Lauf, R. J.: Harris, L. A., and Rawlston, S. S.: 1982, ‘Pyrite Framboids as the Source of Magnetite Spheres in Fly Ash’,Environmental Science and Technology 16, 218–220. Lefevre, R., Gaudichet, A., and Billon-Galland, M. A.: 1986, ‘Silicate Microspherules Intercepted in the Plume of Etna Volcano’,Nature 322, 817–820. Lerbekmo, J. F. and Coulter, K. C.: 1982, ‘Magnetostratigraphic and Biostratigraphic Correlations of Late Cretaceous to Early Paleocene Strata between Alberta and North Dakota’, Canadian Society of Petroleum Geologists,Memoir 9, 313–317. Lerbekmo, J. F. and Coulter, K. C.: 1985, ‘Late Cretaceous to Early Tertiary Magnetostratigraphy of a Continental Sequence: Red Deer Valley, Alberta, Canada’,Canadian Journal of Earth Sciences 22, 567–583. Lerbekmo, J. F. and St. Louis, R. M.: 1986, ‘The Terminal Cretaceous Iridium Anomaly in the Red Deer Valley, Alberta, Canada’,Canadian Journal of Earth Sciences 23, 120–124. Lerbekmo, J. F., Sweet, A. R., and St. Louis, R. M.: 1987, ‘The Relationship between the Iridium Anomaly and Palynological Floral Events at Three Cretaceous-Tertiary Boundary Localities in Western Canada’,Geological Society of America Bulletin 99, 325–330. Lichte, F. E., Wilson, S. M., Brooks, R. R., Reeves, R. D., Holzbecher, J., and Ryan, D. E.: 1986, ‘New Method for the Measurement of Osmium Isotopes Applies to a New Zealand Cretaceous/Tertiary Boundary Shale’,Nature 322, 816–817. Loper, D. E. and McCartney, K.: 1986, ‘Mantle plumes and the periodicity of magnetic field reversals,’Geophysical Research Letters 13, 1525–1528. Loper, D. E. and McCartney, K.: 1988, ‘Shocked Quartz Found at the K/T Boundary’,EOS 69, 961. Loughnan, F. C. and Craig, D. C.: 1960, ‘An Occurrence of Fully-hydrated Halloysite at Muswellbrook, N.S.W.,American Mineralogist 45, 783–790. Lowrie, W., Alvarez, W., and Asaro, F.: 1988, ‘Origin of the Cretaceous/Tertiary White Bed in the Gubbio Section (Italy) (abs.),EOS 69, 1157. Luck, J. M. and Turekian, K. K.: 1983, ‘Osmium-187 in Manganese Nodules and the Cretaceous-Tertiary Boundary’,Science 222, 613–615. Mason, B.: 1971,Handbook of Elemental Abundances in Meteorites, Gordon and Breach, New York, 555 p. Mason, B. and Moore, C. B.: 1982,Principles of Geochemistry (fourth edition), Wiley, New York, 344 p. McCabe, C., Van der Voo, R., Peacor, D. R., Scotese, C. R., and Freeman, R.: 1983, ‘Diagentic Magnetite Carries Ancient yet Secondary Remanence in Some Paleozoic Sedimentary Carbonates’,Geology 11, 221–223. McGookey, D. P.: 1972, ‘The Cretaceous System’, in W. W. Mallory,Geological Atlas of the Rocky Mountain Region, Rocky Mountain Association of Geologists, Denver, 1972 McHone, J. F., Nieman, R. A., Lewis, C. F., and Yates, A. M.: 1989, ‘Stishovite at the Cretaceous-Tertiary Boundary, Raton, New Mexico’,Science 243, 1182–1184. McLaren, D. J.: 1970, ‘Presidential Address: Time, Life, and Boundaries’,Journal of Geology 44, 801–815. McLean, D. M.: 1985, ‘Deccan Traps Mantle Degassing in the Terminal Cretaceous Marine Extinctions’,Cretaceous Research 6, 235–259. Melson, W. G. and Switzer, G.: 1966, ‘Plagioclase-spinelgraphite Xenoliths in Metalic Iron-bearing Basalts, Disko Island, Greenland’,American Mineralogist 51, 664–676 Michel, H. V., Asaro, F., Alvarez, W., and Alvarez, L. W.: 1985, ‘Elemental Profile of Iridium and Other Elements Near the Cretaceous/Tertiary Boundary in Hole 577B’,DSDP Initial Reports 86, 533–538. Montanari, A., Hay, R. L., Alvarez, W., Asaor, F., Michel, H. V., Alvarez, L. W., and Smith, J.: 1983, ‘Spheroids at the Cretaceous-Tertiary Boundary are Altered Impact Droplets of Basaltic Composition’,Geology 11, 668–671. Moore, J. G. and Moore, G. W.: 1984, ‘Deposit from a Giant Wave on the Island of Lanai, Hawaii’,Science 226, 1312–1315. Morgan, J. W.: 1978, ‘Lonar Crater Glasses and High-magnesium Australites: Trace Element Volatization and Meteoritic Contamination’, Proceedings of the 9th Lunar and Planetary Science Conference, 2713–2730. Morgan, J. W., Ganapathy, R., Higuchi, H., Krahenbuhl, U., and Anders, E.: 1974, ‘Lunar Basins: Tentative Characterizations of Projectiles from Meteoritic elements in Apollo 17 Boulders’, Proceedings of the 5th Lunar Science Conference, 1703–1736. Morgan, J. W., Higuchi, H., Ganapathy, R., and Anders, E.: 1975, ‘Meteoritic Material in Four Terrestrial Meteorite Craters’, Proceedings of the 6th Lunar Science Conference, 1609–1623. Morgan, J. W., Wandless, G. A., Petrie, R. K., and Irving, A. J.: 1981, ‘Composition of the Earth's Upper Mantle-I. Siderophile Trace Elements in Ultramafic Nodules’,Tectonophysics 75, 47–67. Morton, A. C., Dixon, J. E., Fitton, J. G., Macintyre, R. M., Smythe, D. K., and Taylor, P. N.: 1988, ‘Early Tertiary Volcanic Rocks in Well 163/6-1A, Rockall Trough’, Geological Society Special Publication 39, 293–308. Mount, J. F., Margolis, S. V., Showers, W., Ward, P., and Doehne, E.: 1986, ‘Carbon and Oxygen Isotipe Stratigraphy of the Upper Maastrichtian, Zumaya, Spain: A Record of Oceanographic and Biologic Changes at the End of the Cretaceous Period’Palaios 1, 87–92. Murali, A. V., Schuraytz, B. C., and Parekh, P. P.: 1988, ‘Deccan Volcanism and K-T Boundary Signatures’, poster presented at Global Catastrophies in Earth History Conference, Snowbird Utah, October 20–23. Mussett, A. E.: 1986, ‘40Ar−39Ar Step-heating Ages of the Tertiary Igneous Rocks of Mull, Scotland’,Journal of the Geological Society 143, 887–896. Musset, A. E., Dagley, P., and Skelhorn, R. R.: 1988, ‘Time and Duration of Activity in the British Tertiary Igneous Province’,Geological Society Special Publication 39, 337–348. Myers, A. T. and Hamilton, J. C.: 1961, ‘Rhenium in Plant Samples from the Colorado Plateau’, U.S. Geological Survey Research, B286–B288. Naslund, H. R., Officer, C. B., and Johnson, G. D.: 1986, ‘Microspherules in Upper Cretaceous and Lower Tertiary Clay Layers at Gubbio, Italy’,Geology 14, 923–926. Nazarov, M. A., Barsukova, L. D., Kolesov, G. M., Naidin, D. P., Alekseev, A. S., and Vernadsky, V. I.: 1985, ‘Data of Ir Geochemistry: Implication for Early History of the Earth's Crust’ (abs.),Lunar and Planetary Science 16, 580–581. Nichols, D. J., Jarzen, D. M., Orth, C. J., and Oliver, P. Q.: 1986, ‘Palynological and Iridium Anomalies at Cretaceous-Tertiary Boundary, South-central Saskatchewan’,Science 231, 714–717. Nordenskiöld, A. E.: 1872, ‘Account of an Expedition to Greenland in the Year 1870’,Geological Magazine 9, 516. Obradovich, J. D. and Sutter, J. F.: 1984, ‘What is the Age of the Cretaceous-Tertiary Boundary as Recognized in Continental Deposits?’ (abs),Geological Society of America 16, 612. Officer, C. B. and Drake, C. L.: 1983, ‘The Cretaceous-Tertiary Transition’,Science 219, 1383–1390. Officer, C. B. and Drake, C. L.: 1985, ‘Terminal Cretaceous Environmental Events’,Science 227, 1161–1167. Officer, C. B. and Drake, C. L.: 1989, ‘Cretaceous/Tertiary Extinctions: We Know the Answer, but What is the Question?’,EOS 70, 659–661. Officer, C. B., Hallam, A., Drake, C. L., and Devine, J. D.: 1987, ‘Late Cretaceous and Paroxysmal Cretaceous/Tertiary Extinctions’,Nature 326, 143–149. O'Keefe, J. D. and Ahrens, T. J.: 1982, ‘Impact Mechanics of the Cretaceous-Tertiary Extinction Bolide’,Nature 298, 123–127. O'Keefe, J. D. and Ahrens, T. J.: 1989, ‘Impact Production of CO2 by the Cretaceous/Tertiary Extinction Bolide and the Resultant Heating of the Earth’,Nature 338, 247–249. Olmez, I., Finnegan, D. L., and Zoller, W. H.: 1986, ‘Iridium Emissions from Kilauea Volcano’,Journal of Geophysical Research 91, 653–663. Orth, C. J., Attrep, M., and Quintana, L. R. 1988, ‘Siderophile Abundance Maxima at Upper Cenomanian Marine Invertebrate Extinction Horizon: Western Interior, North America’, oral presentation at 19th Lunar and Planetary Science Conference, Houston. Orth, C. J., Gilmore, J. S., and Knight, J. D.: 1985, ‘A Search for Evidence of Large Body Earth Impacts Associated with Biological Crisis Zones in the Fossil Record’, Lunar and Planetary Science16, Lunar and Planetary Institute, Houston, 631–632. Orth, C. J., Attrep, M., Jr., Mao, X. Y., Kauffman, E. G., diner, R., and Elder, W. P.: 1988, ‘Iridium Abundance Maxima in the Upper Cenomanian Extinction Interval’,Geophysical Research Letters 15, 346–349. Owen, M. R. and Anders, M. H.: 1988, ‘Evidence from Cathodluminescence for Non-volcanic Origin of Shocked Quartz at the Cretaceous/Tertiary Boundary’,Nature 334, 145–147. Pacey, N. R.: 1984, ‘Bentonites in Chalk of Central Eastern England and their Relation to the Opening of the Northeast Atlantic’,Earth and Planetary Science Letters 67, 48–60. Palme, H.: 1982, ‘Identification of Projectiles of Large Terrestrial Impact Craters and Some Implications for the Interpretation of Ir-rich Cretaceous/Tertiary Boundary Layers’,Geological Society of America, Special Paper 190, 223–233. Pedersen, A. K.: 1975, ‘New Investigations of the Native Iron Bearing Volcanic Rocks of Disko, Central West Greenland’,Gronlands Geologiske Undersogelse 75, 48–51. Peirce, J. and others: 1988, ‘A Tale of Two Ridges’,Nature 335, 593–594. Pillmore, C. L. and Flores, R. M.: 1987, ‘Stratigraphy and Depositional Environments of the Cretaceous-Tertiary Boundary Clay and Associated Rocks, Raton Basin, New Mexico and Colorado’,Geological Society of America, Special Paper 209, 111–130. Pillmore, C. L., Tschudy, R. H., Orth, C. J., Gilmore, J. S., and Knight, J.: 1984, ‘Geologic Framework of Nonmarine Cretaceouos-Tertiary Boundary Sites, Raton Basin, New Mexico and Colorado’,Science 223, 1180–1183. Pollastro, R. M. and Pillmore, C. L., 1987, ‘Mineralogy and petrology of the Cretaceous-Tertiary boundary clay bed and adjacent clay-rich rocks, Raton Basin, New Mexico and Colorado’,Journal of Sedimentary Petrology 57, 456–466. Poplavko, E. M., Ivanov, V. V., Karasik, T. G., Miller, A. D., Orekohov, V. S., Taliyev, S. D., Yu, A. T., and Fadeyeva, V. A.: 1974, ‘On the Concentration of Rhenium in Petroleum, Petroleum Bitumens and Oil Shales’, Geochemistry International, 969–972. Preisinger, A. and others: 1986, ‘The Cretaceous/Tertiary Boundary in the Gosau Basin, Austria’,Nature 322, 794–799. Ramdohr, P.: 1967, ‘Die Schmelzkruste der Meteoriten’,Earth Planetary Science Letters 2, 197–209. Rampino, M. R. and Reynolds, R. C.: 1983, ‘Clay Mineralogy of the Cretaceous-Tertiary Boundary Clay’,Science 219, 495–498. Rampino, M. R. and Stothers, R. B.: 1988, ‘Flood Basalt Volcanismm During the Past 250 Million Years’,Science 241, 663–668. Raup, D. M. and Sepkoski, J. J., Jr.: 1984, ‘Periodicity of Extinctions in the Geologic Past’,Proceedings of the National Academy of Science 81, 801–805. Raup, D. M.: 1988, ‘Impact as a General Cause of Extinction: A Feasibility Test’ (abs.), inGlobal Catastrophes in Earth History: An Interdisciplinary Conference on Impacts, Volcanism, and Mass Mortality, Lunar and Planetary Institute, 148–149. Rehfeldt-Oskierski, A., Stoffler, D., and Hornemann, U.: 1986, ‘Deformation, Transformation, and Thermal Annealing of Experimentally Shocked Single Crystal Quartz’, (abs.), Lunar and Planetary Science,17, Lunar and Planetary Institute, Houston, 697–698. Reimold, W. U. and Horz, F.: 1986, ‘Textures of Experimentally Shocked (5.1–35.5 GPa) Witwatersrand Quartzite’ (abs), Lunar and Planetary Science 17, Lunar and Planetary Institute, Houston, 703–4. Rice, A.: 1987, ‘Shocked Minerals at the K/T Boundary: Explosive Volcanism as a Source’,Physics of the Earth and Planetary Interiors 48, 167–174. Rich, J. E., Johnson, G. L., Jones, J. E., and Campsie, J.: 1986, ‘A Significant Correlation between Fluctuations in Seafloor Spreading Rates and Evolutionary Pulsations’,Paleoceanography 1, 83–95. Rigby, J. K. Jr. and Wolberg, D. L.: 1987, ‘The Therian Mammalian Fauna (Campanian) of Quarry 1, Fossil Forest Study Area, San Juan Basin, New Mexico’,Geological Society of America Special Paper 209, 51–79. Rigby, J. K. Jr., Newman, K. R., Smit, J., Van Der Kaars, S., Sloan, R. E., and Rigby, J. K.: 1987, ‘Dinosaurs from the Paleocene Part of the Hell Creek Formation, McCone County, Montana’,Palaios 2, 296–302. Robertson, P. B., Grieve, R. A. F., Alexopoulos, J., and Coderre, J.: 1987, ‘Shock Metamorphismm at the Vrederfort Structure, South Africa: Evidence for a Single Shock Event’ (abs.),Lunar and Planetary Science 18, 840–841. Rocchia, R., Boclet, D., Courtillot, V., and Jaeger, J. J.: 1988, ‘A Search for Iridium in the Deccan Traps and Inter-traps’,Geophysical Research Letters 15, 812–815. Rocchia, R., Boclet, D., Bonte, P., Buffetaut, E., Orue-Etxebarria, X., Jaeger, J.-J., and Jehanno, C.: 1988, ‘Structure de l'anomalie en Iridium a la Limite Cretace-Tertiaire du Site de Sopelana’,Comptes Rendus Academie des Sciences Paris 307, Serie II, 1217–1223. Rolle, F.: 1985, ‘Late Cretaceous-Tertiary Sediments Offshore Central West Greenland: Lithostratigraphy, Sedimentary Evolution, and Petroleum Potential’,Canadian Journal of Earth Science 22, 1001–1019. Ross, D. I. and Henderson, G.: 1973, ‘New Geophysical Data on the Continental Shelf of Central and Northern West Greenland’,Canadian Journal of Earth Sciences 10, 485–497. Rucklidge, J.: 1982, in D. A. Russell and G. Rice, ‘Cretaceous-Tertiary Extinctions and Possible Terrestrial and Extraterrestrial Causes’,Syllogeus 39, 14. Saito, T., Yamanoi, T., and Kaiho, K.: 1986, ‘End-Cretaceous Devestation of Terrestrial Flora in the Boreal Far East’,Nature 323, 253–255. Sawatsky, H. B.: 1976, ‘Two Probable Late Cretaceous Astroblemes in Western Canada-Eagle Butte, Alberta and Dumas, Saskatchewan’,Geophysics 41, 1261–1271. Scheyer, W.: 1983, ‘Metamorphism and Fluid Inclusions in the Basement of the Vrederfort Dome, South Africa: Guidelines to the Origin of the Structure’,Journal of Petrology 24, 26–47. Schlanger, S. O., Jenkyns, H. C., and Premoli-Silva, I.: 1981, ‘Volcanism and Vertical Tectonics in the Pacific Basin Related to Global Cretaceous Transgressions’,Earth and Planetary Science Letters 52, 435–449. Schmitz, B., 1985: ‘Metal Precipitation in the Cretaceous-Tertiary Boundary Clay at Stevns Klint, Denmark’,Geochimica Cosmochimica Acta 49, 2361–2370. Schmitz, B.: 1988, ‘Origin of Microlayering in Worldwide Distributed Ir-rich Marine Cretaceous/Tertiary Boundary Clays’,Geology 16 1068–1072. Schmitz, B., Andersson, P., and Dahl, J.: 1988, ‘Iridium, Sulfur Isotopes and Rare Earth Elements in the Cretaceous-Tertiary Boundary Clay at Stevns Klint, Denmark’,Geochimica et Cosmochimica Acta 52, 229–236. Sear, C. B., Kelly, P. M., Jones, P. D., and Goodess, C. M.: 1987, Global Surface-Temperature Responses to Major Volcanic Eruptions’,Nature 330, 365–367. Seyfert, C. K. and Sirkin, L. A.: 1979,Earth History and Plate Tectonics, Harper and Row, New York. Seyfried, W. and Bischoff J. L.: 1977, ‘Hydrothermal Transport of Heave Metals by Seawater: The Role of Seawater/Basalt Ratio’,Earth and Planetary Science Letters 34, 71–77. Shackleton, N. J., Hall, M. A., and Boersma, A.: 1984, ‘Oxygen and Carbon Isotope Data from Leg 74 Foraminifers’,DSDP Initial Reports 74, 599–612. Sharpton, V. L., Schuraytz, B. C., Murali, A. V., Ryder, G., and Burke, K.: 1988, ‘K-T Impact(s): Continental, Oceanic, or Both?’ (abs.), inGlobal Catastrophes in Earth History: An Interdisciplinary Conference on Impacts, Volcanism, and Mass Mortality, Lunar and Planetary Institute, Houston, 172–173. Sheath, R. G., Havas, M., Hellebust, J. A., and Hutchinson, T. C.: 1982, ‘Effects of Long-term Natural Acidification on the Algal Communities of Tundra Ponds at the Smoking Hills, N.W.T., Canada’,Canadian Journal of Botany 60, 58–72. Shoemaker, E. M., Pillmore, C. L., and Peacock, E. W.: 1987, ‘Remanent Magnetization of Rocks of Latests Cretaceous and Earliest Tertiary Age from Drill Core at York Canyon, New Mexico’,Geological Society of America, Special Paper 209, 131–150. Shoemaker, E. M., Shoemaker, C. S., and Wolfe, R. F.: 1988, ‘Asteroid and Comet Flux in The Neighborhood of the Earth’,ibid., 174–175. Simkin, T.: 1988, ‘Volcanoes and Global Catastrophes’ (abs. inGlobal Catastrophes in Earth History: An Interdisciplinary Conference on Impacts, Volcanism, and Mass Mortality, Lunar and Planetary Institute, Houston, 179. Sloan, R. E., Rigby, J. K., Van Valen, L. M., and Gabriel, D.: 1986, ‘Gradual Dinosaur Extinction and Simultaneous Ungulate Radiation in the Hell Creek Formation’,Science 232, 629–633. Smit, J., Groot, H., de Jonge, R., and Smit, P.: 1988, ‘Impact and Extinction Signatures in Complete Cretaceous Tertiary (KT) Boundary Sections’, (abs.), inGlobal Catastrophes and in Earth History: An Interdisciplinary Conference on Impacts, Volcanism, and Mass Mortality, Lunar and Planetary Institute, Houston, 182–183. Smit, J. and Klaver, G.: 1981, ‘Sanidine Spherules at the Cretaceous-Tertiary Boundary Indicate a Large Impact Event’,Nature 292, 47–49. Smit, J. and Kyte, F. T.: 1984, ‘Siderophile-rich magnetic spheroids from the Cretaceous-Tertiary boundary in Umbria, Italy,Nature 310, 403–405. Smit, J. and Romein, A. J. T.: 1985, ‘A Sequence of Events across the Cretaceous-Tertiary Boundary’,Earth and Planetary Science Letters 74, 155–170. Smit, J. and ten Kate, W. G. H. Z.: 1982, ‘Trace-element Patterns at the Cretaceous-Tertiary Boundary-Consequences of a Large Impact’,Cretaceous Research 3, 307–332. Srivastava, S. P., Falconer, R. K. H., and MacLean, B.: 1981, ‘Laborador Sea, Davis Strait, Baffin Bay: Geology and Geophysics — A Review’, in J. W. Kerr and A. J. Fergusson,Geology of the North Atlantic Borderlands, Canadian Society of Petroleum Geologists, Calgary, 333–398. Srivastava, S. P., Arthur, M., and Clement, B., and others: 1987, ‘Introduction’, Proceedings of the Ocean Drilling Program, Part A, Initial Reports, 21–41. Stoddard, P. R. and Judy, D. M.: 1988, ‘Age Estimation of the Deccan Traps from the North American Apparent Polar Wander Path’,Geology 16, 296–298. Stoffler, D.: 1972, ‘Deformation and Transformation of Rock-forming Minerals by Natural and Experimental Processes; 1: Behavior of Minerals under High Pressure’,Fortschritte der Mineralogie 49, 50–113. Stothers, R. B., Wolff, J. A., Self, S., and Rampino, M. R.: 1986, ‘Basaltic Fissure Eruptions, Plume Heights, and Atmospheric Aerosols’,Geophysical Research Letters 13, 725–728. Stott, L. D. and Kennett, J. P.: 1989, ‘The Paleoceanographic and Paleoclimatic Signature of the Cretaceous/Tertiary Boundary in the Antarctic: Stable Isotopic Results from ODP Leg 113’, Proceedings of the Ocean Drilling Program, Initial Reports, Leg 113 (in press). Strong, C. P., Brooks, R. R., Wilson, S. M., Reeves, R. D., Orth, C. J., Mao, X-Y., Quintana, L. R., and Anders, E.: 1987, ‘A New Cretaceous-Tertiary Boundary Site at Flaxbourne River, New Zealand: Biostratigraphy and Geochemistry’,Geochimica et Cosmochimica Acta 51, 2769–2777. Sutherland, F. L.: 1983, ‘Timing, Trace and Origin of Basaltic Migration in Eastern Australia’,Nature 305, 123–126. Tappan, H.: 1968, ‘Primary Production, Isotopes, Extinctions and the Atmosphere’, Palaeogeography, Palaeoclimatology,Palaeoecology 4, 187–210. Thiersten, H.: 1982, in D. A. Russell and G. Rice, ‘Cretaceous-Tertiary Extinctions and Possible Terrestrial and Extraterrestrial Causes’,Syllogeus 39, 96–100. Tredoux, M., Verhagen, B. Th., Hart, R. J., De Wit, M. J., Smith, C. B., Perch-Nielsen, K. P., and Sellschop, J. P. F.: 1988, ‘Geochemical Comparison of K-T Boundaries from the Northern and Southern Hemispheres’, inGlobal Catastrophes in Earth History: An Interdisciplinary Conference on Impacts, Volcanism, and Mass Mortality, Lunar and Planetary Science Institute, Houston, 198–199. Turekian, K. K., Esser, B. K., and Ravizza, G. E.: 1988, ‘The Causes for Geographical Variations in187Os/186Os at the Cretaceous-Tertiary Boundary’ibid., 202–203. Tschudy, R. H. and Tschudy, B. D.: 1986, ‘Extinction and Survival of Plant Life Following the Cretaceous/Tertiary Boundary Event, Western Interior, North America’,Geology 14, 667–670. Tschudy, R. H., Pillmore, C. L., Orth, C. J., Gilmore, J. S., and Knight, J. D.: 1984, ‘Disruption of the Terrestrial Plant Ecosystem at the Cretaceous-Tertiary Boundary, Western Interior’,Science 225, 1030–1032. Upton, B. G. J.: 1988, ‘History of Tertiary Igneous Activity in the N Atlantic Borderlands’,The Geologic Society Special Publication 39, 429–453. Urey, H. C.: 1973, ‘Cometary Collisions and Geological Periods’,Nature 242, 32–33. Vallier, T. L. and Jefferson, W. S.: 1981, ‘Volcanogenic Sediments from the Hess Rise and the Mid-Pacific Mountains, Deep Sea Drilling Project Leg 62’,Initial Reports of the Deep Sea Drilling Project 62, 545–557. Venkatesan, M. I. and Dahl, J.: 1989, ‘Organic Geochemical Evidence for Global Fires at the Cretaceous/Tertiary Boundary,’Nature 338, 57–60. Vincent, E. and Berger, W. H.: 1985, ‘Carbon Dioxide and Polar Cooling in the Miocene: the Monterey Hypothesis’ in E. T. Sundquist and W. S. Broecker,The Carbon Cycle and Atmospheric CO 2;Natural Variations Archaen to Present, American Geophysical Union, Washington, 455–468. Vogt, P. R.: 1972, ‘Evidence for Global Synchronism in Mantle Plume Convection, and Possible Significance for Geology’,Nature 240, 338–342. Webb, P. N.: 1973, ‘Upper Cretaceous-Paleocene Foraminifera from Site 208 (Lord Howe Rise, Tasman Sea), DSDP, Leg 21’,DSDP Initial Reports 21, 541–573. Weissman, P. R.: 1985, ‘Terrestrial Impactors at Geological Boundary Events: Comets or Asteroids?’Nature 314, 517–518. Welhan, J. A. and Craig, H.: 1982, ‘Abiogenic Methane in Mid-ocean Ridge Hydrothermal Fluids’, in W.J. Gwilliam (ed.),Deep Source Gas Workshop Technical Proceedings, U.S. Dept. of Energy, Morgantown, 122–129. Wolbach, W. S., Lewis, R. S., and Anders, E.: 1985, ‘Cretaceous Extinctions: Evidence for Wildfires and Search for Meteoritic Material’,Science 230, 167–170. Wolbach, W. S., Gilmour, I., Anders, E., Orth, C. J., and Brooks, R. R.: 1988a, ‘Global Fire at the Cretaceous-Tertiary Boundary’,Nature 334, 665–669. Wolbach, W. S., Anders, E., and Orth, C. J.: 1988b, ‘Darkness after the K/T Impact: The Effects of Soot’ (abs.), Global Catastrophes inEarth History: An Interdisciplinary Conference on Impacts, Volcanism, and Mass Mortality, Lunar and Planetary Institute, Houston, 219–220. Wörm, H-U., and Banerjee, S. K.: 1987, ‘Rock Magnetic Signature of the Cretaceous-Tertiary Boundary’,Geophysical Research Letters 14, 1083–1086. Zachos, J. C., and Arthur, M. A.: 1986, ‘Paleoceanography of the Cretaceous/Tertiary Boundary Event: Inferences from Stable Isotopic and Other Data’,Paleoceanography 1, 5–26. Zachos, J. C., Arthur, M. A., and Dean, W. E.: 1989, ‘Geochemical Evidence for Suppression of Pelagic Marine Productivity at the Cretaceous/Tertiary Boundary’,Nature 336, 61–64. Zhao, M. and Bada, J. L.: 1989, ‘Extraterrestrial Amino Acids in Cretaceous/Tertiary Boundary sediements at Stevns Klint, Denmark’,Nature 339, 463–465. Zhou, L. and Kyte, F.: 1988, ‘The Permian-Triassic Boundary Event: A Geochemical Study of Three Chinese Sections’,Earth and Planetary Science Letters 90, 411–421. Zoller, W. H., Parrington, J. R., and Phelan Kotra, J. M.: 1983, ‘Iridium Enrichment in Airborne Particles frim Kilauea Volcano: January 1983’,Science 222, 1118–1121.