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Evidence for a Solar Flare Cause of the Pleistocene Mass Extinction

Published online by Cambridge University Press:  18 July 2016

Paul A LaViolette
Paul A LaViolette*
Affiliation:
The Starburst Foundation, 1176 Hedgewood Lane, Niskayuna, New York 12309, USA. Email: starburstfound@aol.com.
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Abstract

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The hypothesis is presented that an abrupt rise in atmospheric radiocarbon concentration evident in the Cariaco Basin varve record at 12,837 ± 10 cal yr BP, contemporaneous with the Rancholabrean termination, may have been produced by a super-sized solar proton event (SPE) having a fluence of ~1.3 × 1011 protons/cm2. A SPE of this magnitude would have been large enough to deliver a lethal radiation dose of at least 3–6 Sv to the Earth's surface, and hence could have been a principal cause of the final termination of the Pleistocene megafauna and several genera of smaller mammals and birds. The event time-correlates with a large-magnitude acidity spike found at 1708.65 m in the GISP2 Greenland ice record, which is associated with high NO-3 ion concentrations and a rapid rise in 10Be deposition rate, all of which are indicators of a sudden cosmicray influx. The depletion of nitrate ions within this acidic ice layer suggests that the snowpack surface at that time was exposed to intense UV for a prolonged period, which is consistent with a temporary destruction of the polar ozone layer by solar cosmic rays. The acidity event also coincides with a large-magnitude, abrupt climatic excursion and is associated with elevated ammonium ion concentrations, an indicator of global fires.

Type
Methods and Developments
Information
Radiocarbon , Volume 53 , Issue 2 , 2011 , pp. 303 - 323
Copyright
Copyright © The American Journal of Science 

References

Alfven, H, Arrhenius, G. 1979. Evolution of the Solar System. Washington, DC: NASA.Google Scholar
Alley, RB, Shuman, CA, Meese, DA, Gow, AJ, Taylor, JC, Cuffey, KM, Fitzpatrick, JJ, Grootes, PM, Zielinski, GA, Ram, M, Spinelli, G, Elder, B. 1997. Visual-stratigraphic dating of the GISP2 ice core: basis, reproducibility, and application. Journal of Geophysical Research 102(C12):26,367–81.Google Scholar
Baales, M, Bittmann, F, Kromer, B. 1999. Verkohlte Bäume im Trass der Laacher See-Tephra bei Kruft (Neuwieder Becken). Ein Beitrag zur Datierung des Laacher See-Ereignisses und zur Vegetation der Alleröd-Zeit am Mittelrhein. Archäologisches Korrespondenzblatt 28:191–204.Google Scholar
Beer, J, Andree, M, Oeschger, H, Siegenthaler, U, Bonani, G, Hofmann, H, Morenzoni, E, Nessi, M, Suter, M, Wölfli, W, Finkel, R, Langway, C Jr. 1984. The Camp Century 10Be record: implications for long-term variations of the geomagnetic dipole moment. Nuclear Instruments and Methods in Physics Research B 5(2):380–4.Google Scholar
Beer, J. 2000. Long-term indirect indices of solar variability. Space Science Reviews 94(1–2):53–66.Google Scholar
Beets, C, Sharma, M, Kasse, K, Bohncke, S. 2008. Search for extraterrestrial osmium at the Allerød-Younger Dryas boundary. Fall AGU Meeting. Abstract #V53A2150.Google Scholar
Creer, KM, Anderson, TW, Lewis, CFM. 1976. Late quaternary geomagnetic stratigraphy recorded in Lake Erie sediments. Earth and Planetary Science Letters 31:37–47.Google Scholar
Dessler, AJ, Parker, EN. 1959. Hydromagnetic theory of geomagnetic storms. Journal of Geophysical Research 64:2239–59.Google Scholar
Dibb, JE, Arsenault, M, Peterson, MC, Honrath, RE. 2002. Fast nitrogen oxide photochemistry in Summit, Greenland snow. Atmospheric Environment 36(15–16):2501–11.Google Scholar
Divari, NB. 1965. Contribution of the circumterrestrial dust cloud to the brightness of the zodiacal light and Fcorona. Astronomicheskiy Zhurnal 42:645–652.Google Scholar
Divari, NB. 1966. Charged dust particles in interplanetary space. Astronomicheskiy Zhurnal 43:192–7.Google Scholar
Divari, NB. 1967. The cosmic dust cloud around the Earth. Soviet Astronomy 10:1017–30.Google Scholar
Dreschhoff, GAM, Zeller, EJ. 1994. 415-year Greenland ice core record of solar proton events dated by volcanic eruptive episodes. Institute of Tertiary-Quaternary Studies - TER-QUA Symposium Series 2:1–24.Google Scholar
Dubowski, Y, Colussi, AJ, Hoffmann, MR. 2001. Nitrogen dioxide release in the 302 nm band photolysis of spray-frozen aqueous nitrate solutions: atmospheric implications. Journal of Physical Chemistry A 105(20):4928–32.Google Scholar
Edwards, WE. 1967. The Late Pleistocene extinction and the dimunition in size of many mammalian species. In: Martin, PS, Wright, HE Jr, editors. Pleistocene Extinctions: The Search for a Cause. New Haven: Yale University Press. p 141–54.Google Scholar
Epelman, S, Hamilton, DR. 2006. Medical mitigation strategies for acute radiation exposure during space flight. Aviation, Space, and Environmental Medicine 77:130–9.Google Scholar
Faith, JT, Surovell, T. 2009. Synchronous extinction of North America's Pleistocene mammals. Proceedings of the National Academy of Sciences (USA) 106:20,641–5.Google Scholar
Finkel, RC, Nishiizumi, K. 1997. Beryllium 10 concentration in the Greenland ice sheet Project 2 ice core from 3–40 ka. Journal of Geophysical Research 102(C12):26,699–706.Google Scholar
Firestone, RB, West, A, Warwick-Smith, S. 2006. The Cycle of Cosmic Catastrophes: How a Stone-Age Comet Changed the Course of World Culture. Rochester: Bear & Co.Google Scholar
Firestone, RB, West, A, Kennett, JP, Becker, L, Bunch, TE, Revay, ZS, Schultz, PH, Belgya, T, Kennett, DJ, Erlandson, JM, Dickenson, OJ, Goodyear, AC, Harris, RS, Howard, GA, Kloosterman, JB, Lechler, P, Mayewski, PA, Montgomery, J, Poreda, R, Darrah, T, Que Hee, SS, Smith, AR, Stich, A, Topping, W, Wittke, JH, Wolbach, WS. 2007. Evidence for an extraterrestrial impact 12,900 years ago that contributed to the megafaunal extinctions and the Younger Dryas cooling. Proceedings of the National Academy of Sciences (USA) 104:16,016–21.Google Scholar
Firestone, RB, West, A, Bunch, TE. 2010. Confirmation of the Younger Dryas boundary (YDB) data at Murray Springs, AZ. Proceedings of the National Academy of Sciences (USA) 107:E105.Google Scholar
Foelsche, T. 1974. Estimates of radiation exposure from solar cosmic rays in SST altitudes. NASA TM X71990.Google Scholar
Grayson, DK. 1977. Pleistocene avifaunas and the overkill hypothesis. Science 196(4279):691–3.Google Scholar
Grayson, DK, Meltzer, DJ. 2003. A requiem for North American overkill. Journal of Archaeological Science 30(5):585–93.Google Scholar
Guilday, JE. 1967. Differential extinction during late-Pleistocene and recent times. In: Martin, PS, Wright, HE Jr, editors. Pleistocene Extinctions: The Search for a Cause. New Haven: Yale University Press. p 121–40.Google Scholar
Haynes, CV Jr. 2006. The Rancholabrean termination: sudden extinction in the San Pedro Valley, Arizona 11,000 B.C. In: Morrow, JE, Gnecco, C, editors. Paleoindian Archeology: A Hemispheric Perspective. Gainesville: University of Florida Press. p 139–63Google Scholar
Haynes, CV Jr. 2008. Younger Dryas “black mats” and the Rancholabrean termination in North America. Proceedings of the National Academy of Sciences (USA) 105:6520–5.Google Scholar
Haynes, CV Jr, Boerner, J, Domanik, K, Lauretta, D, Ballenger, J, Goreva, J. 2010. The Murray Springs Clovis site, Pleistocene extinction, and the question of extraterrestrial impact. Proceedings of the National Academy of Sciences (USA) 107:4010–5.Google Scholar
Hays, JD. 1971. Faunal extinctions and reversals of the Earth's magnetic field. Geological Society of America Bulletin 82:2433–47.Google Scholar
Hays, JD, Opdyke, ND. 1967. Antarctic radiolarea, magnetic reversals and climatic change. Science 158(3804):1001–11.Google Scholar
Hays, JD, Saito, T, Opdyke, ND, Burckle, L. 1969. Pliocene/Pleistocene sediments of the equatorial Pacific: their paleomagnetic biostratigraphic and climatic record. Geological Society of America Bulletin 80:1481–514.Google Scholar
Hua, Q, Barbetti, M, Fink, D, Kaiser, KF, Friedrich, M, Kromer, B, Levchenko, VA, Zoppi, U, Smith, AM, Bertuch, F. 2009. Atmospheric 14C variations derived from tree rings during the early Younger Dryas. Quaternary Science Reviews 28(25–26):2982–90.Google Scholar
Hughen, KA, Southon, JR, Lehman, S, Overpeck, J. 2000. Synchronous radiocarbon and climate shifts during the last deglaciation. Science 290(5498):1951–4.Google Scholar
Isaksson, E, Pohjola, V, Jauhiainen, T, Moore, J, Pinglot, J-F, Vaikmäe, R, van de Wal, RSW, Hagen, J-O, Ivask, J, Karlöf, L, Martma, T, Meijer, HAJ, Mulvaney, R, Thomassen, MPA, Van den Broeke, M. 2001. A new ice-core record from Lomonosovfonna, Svalbard: viewing the 1920–97 data in relation to present climate and environmental conditions. Journal of Glaciology 47(157):335–45.Google Scholar
Jackman, CH, Frederick, JE, Stolarski, RS. 1980. Production of odd nitrogen in the stratosphere and mesosphere: an intercomparison of source strengths. Journal of Geophysical Research 85(C12):7495–505.Google Scholar
Jackman, CH, Peters, RD, Labow, GJ, Fleming, EL, Praderas, CJ, Russell, JM. 2001. Northern hemisphere atmospheric effects due to the July 2000 Solar Proton Event. Geophysical Research Letters 28(15):2883–6.Google Scholar
Jones, AE, Weller, R, Wolff, EW, Jacobi, HW. 2000. Speciation and rate of photochemical NO and NO2 production in Antarctic snow. Geophysical Research Letters 27(3):345–8.Google Scholar
Jones, AE, Weller, R, Anderson, PS, Jacobi, HW, Wolff, EW, Schrems, O, Miller, H. 2001. Measurements of NOx emissions from the Antarctic snowpack. Geophysical Research Letters 28(8):1499–502.Google Scholar
Jull, AJT, Cloudt, S, Donahue, DJ, Sisterson, JM, Reedy, RC, Masarik, J. 1998. 14C depth profiles in Apollo 15 and 17 cores and lunar rock 68815. Geochimica et Cosmocimica Acta 62(17):3025–36.Google Scholar
Jull, AJT, Haynes, V Jr, Donahue, D, Burr, GS, Beck, JW. 1999. Radiocarbon ages at Murray Springs, Arizona and the influence of climate change on Clovis man. In: Proceedings of the 3rd Conference on 14C and Archaeology. Lyons, France, 1998. Mémoires de la Société préhistorique française 26:339–43.Google Scholar
Kennett, DJ, Kennett, JP, West, GJ, Erlandson, JM, Johnson, JR, Hendy, IL, West, A, Culleton, BJ, Jones, TL, Stafford, TW Jr. 2008. Wildfire and abrupt ecosystem disruption on California's Northern Channel Islands at the Allerød-Younger Dryas boundary (13.0–12.9 ka). Quaternary Science Reviews 27(27–28):2530–45.Google Scholar
Kurbatov, A, Mayewski, PA, Steffensen, JP, West, A, Kennett, DJ, Kennett, JP, Bunch, TE, Handley, M, Introne, DS, Que Hee, SS, Mercer, C, Sellers, M, Shen, F, Sneed, SB, Weaver, JC, Wittke, JH, Stafford, TW Jr, Donovan, JJ, Xie, S, Razink, JJ, Stich, A, Kinzie, CR, Wolbach, WS. 2010. Discovery of a nanodiamond-rich layer in the Greenland ice sheet. Journal of Glaciology 56:747–57.Google Scholar
LaViolette, PA. 1983. Galactic explosions, cosmic dust invasions, and climatic change [PhD dissertation]. Portland: Portland State University.Google Scholar
LaViolette, PA. 1985. Evidence of high cosmic dust concentrations in Late Pleistocene polar ice. Meteoritics 20:545–58.Google Scholar
LaViolette, PA. 1987. Cosmic ray volleys from the Galactic center and their recent impact on the Earth environment. Earth, Moon, and Planets 37:241–86.Google Scholar
LaViolette, PA. 1990 Galactic core explosions and the evolution of life. Anthropos 12:239–55.Google Scholar
LaViolette, PA. 2005. Solar cycle variations in ice acidity at the end of the last ice age: possible marker of a climatically significant interstellar dust incursion. Planetary and Space Science 53:385–93.Google Scholar
Legrand, MR, De Angelis, M, Staffelbach, T, Neftel, A, Stauffer, B. 1992. Large perturbations of ammonium and organic acids content in the Summit-Greenland ice core. Fingerprint from forest fires? Geophysical Research Letters 19(5):473–5.Google Scholar
Mahaney, WC, Kalm, V, Krinsley, DH, Tricart, P, Schwartz, S, Dohm, J, Kim, KJ, Kapran, B, Milner, MW, Beukens, R, Boccia, S, Hancock, RGV, Hart, KM, Kelleherk, B. 2010. Evidence from the northwestern Venezuelan Andes for extraterrestrial impact: the black mat enigma. Geomorphology 116(1–2):48–57.Google Scholar
Marlon, JR, Bartlein, PJ, Walsh, MK, Harrison, SP, Brown, KJ, Edwards, ME, Higuera, PE, Power, MJ, Anderson, RS, Briles, C, Brunelle, A, Carcaillet, C, Daniels, M, Hul, FS, Lavoie, M, Long, C, Minckley, T, Richard, PJH, Scott, AC, Shafer, DS, Tinners, W, Umbanhowar, CE Jr, Whitlock, C. 2009. Wildfire responses to abrupt climate change in North America. Proceedings of the National Academy of Sciences (USA) 106:2519–24.Google Scholar
Martin, PS. 1967. Prehistoric overkill. In: Martin, PS, Wright, HE Jr, editors. Pleistocene Extinctions: The Search for a Cause. New Haven: Yale University Press. p 75–120.Google Scholar
McCabe, JR, Boxe, CS, Colussi, AJ, Hoffmann, MR, Thiemens, MH. 2005. Oxygen isotopic fractionation in the photochemistry of nitrate in water and ice. Journal of Geophysical Research 110: D15310.Google Scholar
McCracken, KG, Smart, DF, Shea, MA, Dreschhoff, AM. 2001a. 400 years of large fluence solar proton events. Proceedings of the 27th International Cosmic Ray Conference 8:3209–12.Google Scholar
McCracken, KG, Dreschhoff, GAM, Zeller, EJ, Smart, DF, Shea, MA. 2001b. Solar cosmic ray events for the period 1561–1994. 1. Identification in polar ice, 1561–1950. Journal Geophysical Research 106(A10):21,585–98.Google Scholar
McManus, JF, Francois, R, Gherardi, J-ML, Keigwin, D, Brown-Leger, S. 2004. Collapse and rapid resumption of Atlantic meridional circulation linked to deglacial climate changes. Nature 428(6985):834–7.CrossRefGoogle ScholarPubMed
Mehringer, PJ Jr. 1967. The environment of extinction of the Late Pleistocene megafauna in the arid southwestern United States. In: Martin, PS, Wright, HE Jr, editors. Pleistocene Extinctions: The Search for a Cause. New Haven: Yale University Press. p 247–66.Google Scholar
Melott, AL, Thomas, BC, Dreschoff, G, Johnson, CK. 2010. Cometary airbursts and atmospheric chemistry: Tunguska and a candidate Younger Dryas event. Geology 38(4):355–8.Google Scholar
Meltzer, DJ, Mead, JI. 1985. Dating late Pleistocene extinctions: theoretical issues, analytical bias, and substantive results. In: Mead, J, Meltzer, D, editors. Environment and Extinction: Man in Late Glacial North America. Orono: Center for the Study of Early Man, University of Maine. p 145–73.Google Scholar
Meltzer, DJ. 2004. Peopling of North America. In: Gillespie, AR, Porter, SC, Atwater, BF, editors. The Quaternary Period in the United States. Amsterdam: Elsevier. p 539–63.Google Scholar
Miller, WE. 1987. Mammut Americanum: Utah's first record of the American mastodon. Journal of Paleontology 61:168–83.Google Scholar
Mueller, G, Hinsch, GW. 1970. Glassy particles in lunar fines. Nature 228(5268):254–8.Google Scholar
Muscheler, R, Beer, J, Wagner, G, Finkel, RC. 2000. Changes in deep-water formation during the Younger Dryas event inferred from 10Be and 14C records. Nature 408(6812):567–70.Google Scholar
Napier, WM. 2010. Palaeolithic extinctions and the Taurid complex. Monthly Notices of the Royal Astronomical Society 405(3):1901–6.Google Scholar
Paquay, FS, Goderis, S, Ravizza, G, Vanhaeck, F, Boyd, M, Surovell, TA, Holliday, VT, Haynes, CV Jr, Claeys, P. 2009. Absence of geochemical evidence for an impact event at the Bølling-Allerød/Younger Dryas transition. Proceedings of the National Academy of Sciences (USA) 106(51):21,505–10.Google Scholar
Parkin, DW, Sullivan, RAL, Andrews, JN. 1977. Cosmic spherules as rounded bodies in space. Nature 266(5602):555–7.Google Scholar
Ram, M, Stolz, M. 1999. Possible solar influences on the dust profile of the GISP2 ice core from Central Greenland. Geophysical Research Letters 26(8):1043–6.Google Scholar
Ram, M, Stolz, M, Koenig, G. 1997. Eleven year cycle of dust concentration variability observed in the dust profile of the GISP2 Ice core from Central Greenland: possible solar cycle connection. Geophysical Research Letters 24(19):2359–62.Google Scholar
Rasmussen, SO, Seierstad, IK, Andersen, KK, Bigler, M, Dahl-Jensen, D, Johnsen, SJ. 2008. Synchronization of the NGRIP, GRIP, and GISP2 ice cores across MIS 2 and palaeoclimatic implications. Quaternary Science Reviews 27(1–2):18–28.Google Scholar
Reid, GC, Isaksen, ISA, Holzer, TE, Crutzen, PJ. 1976. Influence of ancient solar-proton events on the evolution of life. Nature 259(5540):177–9.Google Scholar
Rietmeijer, FJM. 2006. Natural Fullerenes and Related Structures of Elemental Carbon. Volume 6. Dordrecht: Springer. p 123–44.Google Scholar
Schaefer, BE, King, JR, Deliyannis, CP. 2000. Superflares on ordinary solar-type stars. Astrophysical Journal 529:1026–30.Google Scholar
Scott, AC, Pinter, N, Collinson, ME, Hardiman, M, Anderson, RS, Brain, APR, Smith, SY, Marone, F, Stampanoni, M. 2010. Fungus, not comet or catastrophe, accounts for carbonaceous spherules in the Younger Dryas “impact layer.” Geophysical Research Letters 37, L14302, doi:10.1029/2010GL043345.Google Scholar
Senatorov, VN. 2000. On the possible existence of radiation dust belts in near-Earth space. Cosmic Research 38:612–5.Google Scholar
Shumilov, OI, Kasatkina, EA, Henriksen, K, Vashenyuk, EV. 1996. Enhancement of stratospheric aerosols after solar proton event. Annales Geophysicae 14(11):1119–23.Google Scholar
Shukla, PK. 2001. A survey of dusty plasma physics. Physics of Plasmas 8:1791–803.Google Scholar
Sickafoose, AA, Colwell, JE, Horányi, M, Robertson, S. 2000. Photoelectric charging of dust particles in vacuum. Physics Review Letters 84(26):6034–7.Google Scholar
Skeels, MA. 2002. The mastodons and mammoths of Michigan. Michigan Academician 34:254.Google Scholar
Slaughter, BH. 1967. Animal ranges as a clue to Late-Pleistocene extinction. In: Martin, PS, Wright, HE Jr, editors. Pleistocene Extinctions: The Search for a Cause. New Haven: Yale University Press. p 155–67.Google Scholar
Steffensen, JP, Andersen, KA, Bigler, M, Clausen, HB, Dahl-Jensen, D, Fischer, H, Goto-Azuma, K, Hansson, M, Johnsen, SJ, Jouzel, J, Masson-Delmotte, V, Popp, T, Rasmussen, SO, Röthlisberger, R, Ruth, U, Stauffer, B, Siggaard-Andersen, M-L, Sveinbjörnsdóttir, ÁE, Svensson, A, White, JWC. 2008. High-resolution Greenland ice core data show abrupt climate change happens in few years. Science 321(5889):680–4.Google Scholar
Stich, A, Howard, G, Kloosterman, JB, Firestone, RB, West, A, Kennett, JP; Kennett, DJ, Bunch, TE, Wolbach, WS. 2008. Soot as evidence for widespread fires at the Younger Dryas onset (YDB; 12.9 ka). American Geophysical Union, Fall Meeting 2008, abstract #PP13C–1471.Google Scholar
Stocker, TF, Wright, DG. 1996. Rapid changes in ocean circulation and atmospheric radiocarbon. Paleoceanography 11:773–95.Google Scholar
Stuiver, M, Kra, RS. 1986. High-precision calibration of the radiocarbon time scale, AD 1950–500 BC. Radiocarbon 28(2B):805–38.Google Scholar
Stuiver, M, Grootes, PM. 2000. GISP2 oxygen isotope ratios. Quaternary Research 53(3):277–84.Google Scholar
Surovell, TA, Holliday, VT, Gingerich, JAM, Ketron, C, Haynes, CV Jr, Hilman, I, Wagner, DP, Johnson, E, Claeys, P. 2009. An independent evaluation of the Younger Dryas extraterrestrial impact hypothesis. Proceedings of the National Academy of Sciences (USA) 106(43):18,155–8.CrossRefGoogle ScholarPubMed
Taylor, KC, Hammer, CU, Alley, RB, Clausen, HB, Dahl-Jensen, D, Gow, AJ, Gundestrup, NS, Kipfstuh, J, Moore, JC, Waddington, ED. 1993. Electrical conductivity measurements from the GISP2 and GRIP Greenland ice cores. Nature 366(6455):549–52.Google Scholar
Taylor, KC, Mayewski, PA, Twickler, MS, Whitlow, SI. 1996. Biomass burning recorded in the GISP2 ice core: a record from eastern Canada? The Holocene 6(1):1–6.Google Scholar
Tian, H, Schryvers, D, Claeys, P. 2011. Nanodiamonds do not provide unique evidence for a Younger Dryas impact. Proceedings of the National Academy of Sciences (USA) 108:40–4.Google Scholar
Tverskoi, BA. 1967. The influence of corpuscular radiation on the circumterrestrial cloud. Soviet Astronomy 10:1031–3.Google Scholar
Usoskin, IG, Solanki, SK, Kovaltsov, GA, Beer, J, Kromer, B. 2006. Solar proton events in cosmogenic isotope data. Geophysical Research Letters 33(8): L08107.Google Scholar
Vereshchagin, NK. 1967. Primitive hunters and Pleistocene extinction in the Soviet Union. In: Martin, PS, Wright, HE Jr, editors. Pleistocene Extinctions: The Search for a Cause. New Haven: Yale University Press. p 365–98.Google Scholar
Wagner, G, Beer, J, Masarik, J, Muscheler, R, Kubik, PW, Mende, W, Laj, C, Raisbeck, GM, Yiou, F. 2001. Presence of the solar de Vries cycle (~205 years) during the last ice age. Geophysical Research Letters 28(2):303–6.Google Scholar
Waters, MR, Stafford, TW Jr. 2007. Redefining the Age of Clovis: implications for the peopling of the Americas. Science 315(5815):1122–6.Google Scholar
Wolff, EW. 1995. Nitrate in Polar Ice. New York: Springer-Verlag.Google Scholar
Yang, Q, Mayewski, PA, Whitlow, SI, Twickler, MS, Morrison, MC, Talbot, RW, Dibb, JE, Linder, E. 1995. Global perspective of nitrate flux in ice cores. Journal of Geophysics Research 100(D3):5113–21.Google Scholar
Zeller, EJ, Dreschhoff, GAM. 1995. Anamalous nitrate concentrations in polar ice cores—Do they result from solar particle injections into the polar atmosphere? Geophysical Research Letters 22(18):2521–4.Google Scholar
Zook, HA, Hartung, JB, Storzer, D. 1977. Solar flare activity: evidence for large-scale changes in the past. Icarus 32:106–26.Google Scholar
Zook, HA. 1980. On lunar evidence for a possible large increase in solar flare activity ~2 × 104 years ago. In: Peppin, R, Eddy, J, Merril, R, editors. In: The Ancient Sun: Fossil Record in the Earth, Moon and Meteorites. New York: Pergamon Press. p 245–66.Google Scholar