"The causes of the extermination are two.... (1) a colder climate.... (2) earthquake waves produced by orogenic movements (movements producing mountain ranges). If North America from the west of the Carolinas to the Mississippi Valley can be shaken in consequence of a little slip along a fracture in times of perfect quiet (the allusion here to the Charleston earthquake, in 1886), and ruin mark its movements, incalculable violence and great surgings of the ocean should have occurred and been often repeated during the progress of flexures, miles in height and space, and slips along newly opened fractures that kept up their interrupted progress through thousands of feet of displacements.... "Under such circumstances the devastation of the sea-border and the low-lying land of the period, the destruction of their animals and plants, would have been a sure result. The survivors within a long distance of the coastline would have been few. The same waves would have swept over European land and seas, and there found coadjutors for new strife in earthquake waves of European origin. These times of catastrophe may have continued in America through half of the following Triassic period; for fully two thirds of the Triassic period are unrepresented by rocks and fossils on the Atlantic border." Coming now to the Post-Mesozoic revolution this period was marked by the making of the greatest of the North American mountain systems. Dana points out that this revolution affected the summit region of the Rocky Mountains over a broad belt probably as long as the western side of the continent. This great belt of mountain-making extended from the Arctic regions through North America, probably paralleled by like work, of equal extent, in South America, but on a more eastern line. "The disappearance of species," says Dana, "at the close of Mesozoic time was one of the two most noted in all geological history. Probably not a tenth part of the animal species of the world disappeared at the time, and far less of the vegetable life and terrestrial Invertebrates; yet the change was so comprehensive that no Cretaceous species of Vertebrate is yet known to occur in the rocks of the American Tertiary, and not even a marine Invertebrate."