Free Frozen Earth: The Once and Future Story of Ice Ages by Doug Macdougall

discovered something important.When they took him out into the Alpine valleys and showed him the moraines, erratic boulders, and glacial scratches and grooves, it was a revelation.When he returned to Neuchâtel that autumn, he was like a blind man suddenly given sight: he saw signs of glaciation—especially erratic boulders and glacial scratches—everywhere around him.And, together with his long-time friend from student days, the botanist Karl Schimper (the same Schimper who coined the phrase “ice age,” and who was now working with Agassiz in Neuchâtel and living in the family home), he synthesized these observations and soon came up with a theory.With the zeal of a convert, Agassiz took up the cause of past glaciation and did his mentors one better: he proposed a period of global frigidity in the past, not just one in which glaciation in the Alps and a few other regions of Europe had been more extensive.
    The announcement of Agassiz’s ice age theory came only a year after his sojourn with de Charpentier in Bex.In 1837, the Natural History Society of Switzerland met in Neuchâtel, and Agassiz, as president of the society and host of the gathering, gave the introductory address.The delegates, who expected that Agassiz would discuss fossil fish or one of his other biological interests, were in for a surprise.After expressing his pleasure in welcoming them to Neuchâtel, and extolling the advances that were occurring in the sciences, Agassiz said that he wished to focus on a topic appropriate to the location: glaciers, moraines, and erratic boulders.Carefully acknowledging his debt to de Charpentier and Venetz, he laid out a comprehensive ice age hypothesis that presaged his book Studies on Glaciers, which would be published three years later.The address was the pivotal event that brought the idea of an ice age to the full attention of scientists.In the context of what had gone before, it was a grandiose scheme, and it generated instant and long-lasting controversy.What was truly new was Agassiz’s proposition that during the ice age, a great sheet of ice hadextended from the North Pole to the Mediterranean, before the Alps had even been formed.This was very different from the idea that Alpine glaciers had extended a bit further down their valleys in the past.It took even his friends Venetz and de Charpentier by surprise.Furthermore, Agassiz brought zoology into the picture by proposing that the ice age had extinguished many of the Earth’s living creatures.And implicit in his theory was the idea that there had been significant climatic variations in the Earth’s past.The conventional wisdom at the time was that the Earth had been cooling since its creation.Agassiz suggested instead that each geological period (already geologists had subdivided the Earth’s past into different periods based on the fossil record) had had an equable, stable, climate, but was terminated by a frigid episode, after which temperatures recovered, albeit perhaps not quite to their previous level.
    One imagines that many in the audience rolled their eyes.The scope of this scheme was too much even for de Charpentier, who was the person most responsible for convincing Agassiz that Alpine glaciation had once been much more extensive.Agassiz, even in his enthusiasm for this new (for him) subject, recognized that there was likely to be some adverse reaction.Toward the end of his address (which was later published) he said:
I am afraid that this approach will not be accepted by a great number of our geologists, who have well-established opinions on this subject, and the fate of this question will be that of all those that contradict traditional ideas. Whatever the opposition to this approach, it is unquestionable that the numerous and new facts mentioned above concerning the transportation of boulders, which may easily be studied in the Rhône valley and in the vicinity of Neuchâtel, have completely changed the context in which the question has