Anker: When did scientists begin to make this distinction?

Membur: Geologist Arnold Hague, who surveyed Yellowstone from 1883 to 1889, recognized that there were major differences between these two volcanic episodes, but regarded the variations as successive stages in a single major event. Nevertheless, he produced a map that remained the best summary of Yellowstone's geologic history for over 80 years. In 1922, Professor Jagger at the Massachusetts Institute of Technology visited the Yellowstone region on horseback and recognized that the area was geologically active.

Inspector: I've memorized Jagger's words, too. Listen! "Anyone who has spent summers with pack-train in a place like Yellowstone comes to know the land to be leaping. . .the mountains are falling all the time and by millions of tons. Something underground is shoving them up."

Iva: Michael Cuestyon, if you can't be quiet, you're going to have to leave the room! I want to listen!