Catastrophes!: Earthquakes, Tsunamis, Tornadoes, and Other Earth-Shattering Disasters

9 Ice Ages: Frozen Planet

9 Ice Ages Frozen Planet Some say the world will end in fire, Some say in ice. From what I’ve tasted of desire I hold with those who favor fire. But if it had to perish twice, I think I know enough of hate To say that for destruction ice Is also great And would suffice. —Robert Frost, Fire and Ice, 1920 Outrage in Neuchâtel In 1837, the Schweizerische Naturforschende Gesellschaft (Swiss Society of Natural Sciences) held its annual meeting in Neuchâtel, Switzerland. Surrounding the town were the towering cliffs of the tightly folded rocks of the Jura Mountains (from which the “Jurassic” Period got its name) and deep U-shaped valleys where remnants of glaciers could still be seen (fig. 9.1). Fig. 9.1. Zermatt Glacier in the Swiss Alps, illustrated by Louis Agassiz in his 1840 book on the ice ages. Note the people for scale. (From Agassiz 1840) 218 Catastrophes! Already one of the foremost scientific societies in Europe, the Schweizerische Naturforschende Gesellschaft was founded in 1815 to bring together the many Naturforschende Gesellschaften that had sprung up since 1746 in Zurich, Bern, Geneva, Basel, and most other larger Swiss cities. These societies maintained their own libraries and collections, and some even had botanical gardens . Their meetings and publications spread the development of natural history in Europe. The most prominent Swiss thinkers as well as scholars of many other nationalities participated. The Neuchâtel meeting was like most others, with many presentations and reports on discoveries in botany, zoology, geology, mathematics, physics, and chemistry. A pioneering paper by Amanz Gressly on the important geological concept of sedimentary facies was presented but was soon overshadowed by the presentation of Louis Agassiz, a 36-year-old paleontologist and professor at the University of Neuchâtel (fig. 9.2). He was expected to give yet another talk on his continuing research into fossil fishes. Instead, Agassiz shocked his audience with a bold claim that the great glaciers still visible in the Swiss Alps had once covered all of Europe during an ice age, or Eiszeit. Distinguished scholars at the meeting were appalled and scandalized because the prevailing dogma maintained that the mysterious “drift” deposits were left by Noah’s Flood, not by glaciers. Agassiz and his critics quickly organized a postmeeting field trip to the Alpine glaciers to see the evidence for themselves. (This could never happen today in the strictly run and structured scientific meetings, where unbreakable plane reservations prevent anyone from planning a spontaneous postmeeting field trip.) Some prominent senior geologists in the world, including Elie de Beaumont and Leopold von Buch, viewed the evidence Agassiz had described , but they remained skeptical. Agassiz, in turn, was publicizing the thoughts of many other alpine experts, such as Ignaz Venetz, Karl Friedrich Schimper, and Jean de Charpentier. These men had worked on the idea of an ice age for years and had shown Agassiz how glaciers had once spread across Europe and left huge out-of-place boulders called erratics all over the landscape. Ice Ages 219 Agassiz followed his 1837 paper with an 1840 book, Etudes sur les glaciers (Studies on Glaciers). He not only outlined the evidence for how alpine glaciers moved and what deposits they left behind but went beyond his colleagues and mentors who thought that only individual lobes of glaciers were needed to explain the erratic boulders far from their source area. Agassiz argued that Fig. 9.2. Portrait of Louis Agassiz near the Unteraar Glacier, painted by Alfred Berthoud. (Courtesy Wikimedia Commons) 220 Catastrophes! thick ice sheets had once covered all of Europe. That same year he visited Great Britain and went on geological excursions with the prominent geologists William Buckland and Charles Lyell. He accompanied Buckland through Scotland, where they saw many examples of glacial deposits. Soon, both Buckland and Lyell were converts. Most European scientists were unconvinced. They had no direct experience even with Swiss alpine glaciers, let alone with continental-scale glaciers, and could not imagine their neighborhood under a mile-thick pile of ice. In 1852, the explorer Elisha Kent Kane returned from a harrowing voyage with a thrilling account of his experiences with the Greenland ice sheet. Soon people began to understand that Agassiz’s ideas were not so outrageous. Agassiz immigrated to the United States in 1846, where he assumed a professorship at Harvard University and founded the university’s Museum of...