Venetz picked up on and developed ideas about puzzling aspects of glaciation before his better-known friend and colleague Charpentier, whom he helped to persuade. They were in the habit of meeting and discussing ideas, as they did when Agassiz (and Schimper) came to stay with Charpentier in 1836; it was these two younger men who developed a full theory of glaciation and of a widespread ice-age.
Silliman was Maclure’s colleague and published much of his geological research. Maclure had visited Pestalozzi, whose ideas he admired, in Switzerland, but failed to persuade him to move to the U.S; Neef, who had worked with Pestalozzi, was enticed to emigrate. Maclure visited Owen at New Lanark; the experimental community at New Harmony was inspired by Owen, although he and Maclure argued over the practical application of utopian philosophies. Say, who had accompanied Maclure on a previous geological expedition, joined in this failed attempt at an ideal community, as did Lesueur and Neef
Agassiz studied glaciation in the Alps with Charpentier, falling out with his friend Schimper over which of them deserved credit for the theory of the Ice Age (Schimper working the main ideas out first, Agassiz – ever the self-promoter – omitting his name when he published). He classified Brazilian fish (in Latin) for Martius. He studied under Cuvier and Humboldt in Paris; Longfellow and Emerson were friends after his arrival in the U.S.; Edward Morse and James were among his students. Thoreau supplied him with freshwater turtles for his research, and Darwin admired his work on glaciation, despite Agassiz’ strong opposition to Darwinism.
Le Conte studied with Gray and Agassiz, and accompanied Agassiz on expeditions. He moved to California in fear of post-Civil-War politics in the southern states (he was not a supporter of racial equality), and befriended Muir, with whom he helped found the Sierra Club; perhaps fittingly, Le Conte died in Yosemite.
One of the founders of modern geology. When the middle-aged Hutton returned to the intellectual ferment of Edinburgh, Smith, Black and Watt became his most important friends. Most, along with Hume and Ferguson, were members of the convivial and influential ‘Poker Club’, with its sherry, claret and shilling dinners. Hutton and Playfair made a voyage to examine coastal rock formations, though Playfair (who helped spread his ideas) regretted that Hutton’s dense prose got in the way of his work’s appreciation. On a geological tour of England, Hutton dragged Watt around salt-mines and conducted elaborate experiments with Edgeworth and Darwin.