A Wilder Time. William E. Glassley

profound. Feiko Kalsbeek, Bob Pidgeon, and Paul Taylor reported finding along the northern limits of the mobile belt, near the inland ice, remnants of the same type of rocks as those found today in the Andes and the Sierra Nevada range in California.^* Although nearly 2,000 million years older, those rocks were evidence that what is happening in the Andes today had happened in Greenland. In the case of the Andes, the continent of South America moves west, riding over the floor of the Pacific Ocean and pushing it hundreds of miles below the surface. Plunging into the incandescent heat of Earth’s interior, generating massively destructive earthquakes, the ocean floor partially melts, giving rise to bodies of molten rock that slowly make their way back to the surface. The volcanoes of the Andes and the mountainous spine they decorate are the result of that process. If the analogy was accurate, somewhere hidden within the Nagssugtoqidian mobile belt there should be evidence of a vanished Pacific, but no evidence of such a thing had yet been found.

The shear zones of Escher and Watterson. The arrows show the inferred direction of movement on either side of the zones. The vertical line shows the location of the cross section in the figure on page 60. Modified from a drawing by Kai Sørensen.