Gerta Keller

Gerta Keller (born 7 March 1945) is a paleontologist who contests the Alvarez hypothesis that the impact of the Chicxulub impactor, or another large celestial body, caused the Cretaceous–Paleogene extinction event. Keller maintains that such an impact predates the mass extinction and that Deccan volcanism and its environmental consequences were the most likely major cause possibly exacerbated by the impact.[1][2]

Gerta Keller
Born7 March 1945
Alma materSan Francisco State University (B.S.)
Stanford University (Ph.D.)

Early life and educationEdit

Keller was raised in Switzerland on a dairy farm, the sixth of 12 children. She grew up in poverty. In the one-room schoolhouse where she was educated, boys were given training in math and science while girls were taught cooking and cleaning, the skills they would need to be proper housewives. Her hunger for knowledge led her to read the textbooks assigned to her elder siblings, and she would prepare summaries of the material for her brothers and sisters.[3]

She attended a vocational school starting at age 14 and learned sewing. There she organized a protest against rules that required female students to wear skirts, as she rode her bicycle three miles each way to school and wanted to be able to protect herself from the cold. The female students won the right to wear pants from then on.

After receiving her vocational certificate at age 17, she went to work for Pierre Cardin, where she was paid the equivalent of 25 cents per hour to sew luxury gowns that would sell for as much as $1,000 for which she was paid $12. She traveled around the world, learning English and working in England, followed by travel to North Africa, Spain and Australia. She survived being shot in a bank robbery in Australia in 1965, despite awakening in a hospital intensive care unit to find a priest pressing her to confess, telling her that she was going to die.[3][4]

After ending up in San Francisco in 1968, Keller was "freaked out" by the shots and tear gas launched at student protests; she chose to focus on education and took a high school equivalency exam. She received her undergraduate degree at San Francisco State University and received a doctorate in geology and paleontology from Stanford University in 1978.

PaleontologyEdit

After earning her doctorate, Keller worked for the United States Geological Survey and Stanford.[3] She came to Princeton University in 1984 and after a few years started studying the Cretaceous–Paleogene boundary (K–T boundary), the geological signature of the Cretaceous–Paleogene extinction event.[5] Keller's research has led her to conclude that the Chicxulub asteroid impact, the leading hypothesized cause for the Cretaceous–Paleogene extinction event,[6] predates the event to the degree that it could not have been the sole cause. "I'm sure the day after, they had a headache," Keller states, further stating that "we vastly overestimate the damage to the environment and to life that this Chicxulub impact had".[7]

The main evidence for the Alvarez hypothesis that the Chicxulub impact resulted in the Cretaceous–Paleogene extinction event, supported by earth sciences consensus,[6] comes from the presence around the world of shocked quartz granules, glass spherules and tektites embedded in a layer of clay with extremely high levels of iridium, all signs of an asteroid impact. Keller's research found layers where the glass spherules and the iridium clay are separated by as much as 8 feet (2.4 m) of sandstone and other material. Supporters of the Alvarez hypothesis have concluded that the sandstone is the result of a massive tsunami caused by the Chicxulub impact that sandwiched the sand between the shocked quartz layer and the iridium clay. Keller's analysis of the strata between the spherules and iridium clay concludes that the material was laid down over as much as 300,000 years based on signs of plankton, worms and weathering found on the intervening material.[8]

Selected publicationsEdit

  • Blair Schoene; Kyle M. Samperton; Michael P. Eddy; Gerta Keller; Thierry Adatte; Samuel A. Bowring; Syed F. R. Khadri; Brian Gertsch (2014). "U-Pb geochronology of the Deccan Traps and relation to the end-Cretaceous mass extinction". Revue Science. 347 (6218): 182. Bibcode:2015Sci...347..182S. doi:10.1126/science.aaa0118. PMID 25502315.
  • Keller G, Abramovich S, Berner Z, Adatte T (1 January 2009). "Biotic effects of the Chicxulub impact, K–T catastrophe and sea level change in Texas". Palaeogeography, Palaeoclimatology, Palaeoecology. 271 (1–2): 52–68. Bibcode:2009PPP...271...52K. doi:10.1016/j.palaeo.2008.09.007.
  • Gerta Keller; Thierry Adatte; Alfonso Pardo Juez; Jose G. Lopez-Oliva (2009). "New evidence concerning the age and biotic effects of the Chicxulub impact in NE Mexico". Journal of the Geological Society. 166 (3): 393–411. Bibcode:2009JGSoc.166..393K. doi:10.1144/0016-76492008-116.
  • Gerta Keller; T. Adatte; S. Gardin; A. Bartolini; S. Bajpai (30 April 2008). "Main Deccan volcanism phase ends near the K–T boundary: Evidence from the Krishna–Godavari Basin, SE India". Earth and Planetary Science Letters. 268 (3–4): 293–311. Bibcode:2008E&PSL.268..293K. doi:10.1016/j.epsl.2008.01.015.
  • Gerta Keller; Thierry Adatte; Zsolt Berner; Markus Harting; Gerald Baum; Michael Prauss; Abdel Tantawy; Doris Stueben (30 March 2007). "Chicxulub impact predates K–T boundary: New evidence from Brazos, Texas". Earth and Planetary Science Letters. 255 (3–4): 339–356. Bibcode:2007E&PSL.255..339K. doi:10.1016/j.epsl.2006.12.026.
  • Gerta Keller (2007). Impact stratigraphy: Old principle, new reality. GSA Special Papers. 437. pp. 147–178. doi:10.1130/2008.2437(09). ISBN 978-0-8137-2437-9.
  • Keller G, Adatte T, Stinnesbeck W, Rebolledo-Vieyra, Fucugauchi JU, Kramar U, Stueben D (2004). "Chicxulub impact predates the K-T boundary mass extinction". PNAS. 101 (11): 3753–3758. Bibcode:2004PNAS..101.3753K. doi:10.1073/pnas.0400396101. PMC 374316. PMID 15004276.CS1 maint: multiple names: authors list (link)
  • Gerta Keller; W. Stinnesbeck; T. Adatte; D. Stueben (September 2003). "Multiple impacts across the Cretaceous–Tertiary boundary". Earth-Science Reviews. 62 (3–4): 327–363. Bibcode:2003ESRv...62..327K. doi:10.1016/S0012-8252(02)00162-9.
  • Keller, Gerta; MacLeod, N., eds. (1996). Cretaceous-Tertiary Mass Extinctions : Biotic and Environmental Changes. W. W. Norton & Co. ISBN 978-0-393-96657-2.
  • Ward W. C.; Keller G.; Stinnesbeck W.; Adatte T. (October 1995). "Yucatán subsurface stratigraphy: Implications and constraints for the Chicxulub impact". Geology. 23 (10): 873–876. Bibcode:1995Geo....23..873W. doi:10.1130/0091-7613(1995)023<0873:YNSSIA>2.3.CO;2.

ReferencesEdit

  1. ^ "The Dissenter". Retrieved 5 December 2012.
  2. ^ "Massive volcanoes, meteorite impacts delivered one-two death punch to dinosaurs". Retrieved 5 December 2012.
  3. ^ a b c Hedges, Chris (17 December 2003). "PUBLIC LIVES; Where Dinosaurs Roamed, She Throws Stones". The New York Times. Retrieved 5 December 2012.
  4. ^ Stone, Richard (2014). "Back from the dead". Science. 346 (6215): 1281–1283. doi:10.1126/science.346.6215.1281. PMID 25504698.
  5. ^ Schultz, Steven. "Dinosaur dust-up: Princeton paleontologist produces evidence for new theory on extinction", Princeton Weekly Bulletin, September 22, 2003. Accessed June 11, 2009.
  6. ^ a b Schulte, P.; et al. (2010). "The Chicxulub Asteroid Impact and Mass Extinction at the Cretaceous-Paleogene Boundary" (PDF). Science. 327 (5970): 1214–1218. Bibcode:2010Sci...327.1214S. doi:10.1126/science.1177265. PMID 20203042.
  7. ^ Velasquez-Manoff, Moises. "Did Asteroids Really Do in the Dinosaurs?: Scientists Challenge the Story of How the Dinosaurs' 160-Million-Year Reign Came to an End", ABC News, May 24, 2009. Accessed June 11, 2009.
  8. ^ Lovett, Richard A. "'Dinosaur Killer' Asteroid Only One Part of New Quadruple-Whammy Theory", National Geographic, October 30, 2006. Accessed June 16, 2009.

External linksEdit