File:The continent we live on (1961) (20496985120).jpg

Title: The continent we live on
Identifier: continentweliveo00sandrich (find matches)
Year: 1961 (1960s)
Authors: Sanderson, Ivan Terence, 1911-1973
Subjects: Physical geography; Natural history
Publisher: New York : Random House
Contributing Library: New College of California
Digitizing Sponsor: Internet Archive

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hills named Palos Vcrdes. On the seaward side of this there are cliffs several hundred feet high, in places droppinR straight into the sea. in other places descending by sleep slopes Upon a stretch of the latter a pleasant residential area was laid out only a few years ago. with a beach club and many fine homes, sur- rounded by ornamental trees and shrubbery. Today the entire Mte is a grotesque shambles. The whole face of the cliff is slipping or creeping downward to the sea at a pace that, although it cannot be observed by the eye. is remarkable Roads are half fallen away: drainage pipes stick out of the side of cliffs and then start again way below; some houses are twisted or even completely upended; others are cut in half or have been taken apart in great angular chunks and the chunks then piled up crazily. The inhabitants have just left everything as they installed it and gone elsewhere. Notable is the fact that the vegetation seems not to be so adversely affected as the works of man. A few trees or shrubs have been overthrown and some now grow at sharp angles: otherwise they seem to creep downward with the earth, so that some may be seen growing merrily in the middle of colorfully furnished living rooms or thrusting through garages. The same type of movement is going on over the greater part of the earth, though much more slowly. Here it is merely a slipping of uncompacted surface material; in other places it is an inexorable creeping of solid rock strata. And. if you want to appreciate how mudi solid rodcs can flow, obtain a geological map of England and Wales in color, and you will clearly see that strata which were once about Liverpool have now bulged south- ward between the mountains of Wales and the Pcnnlncs in Eng- land almost to the Bristol Channel, some sixty miles away. An even more impressive piece of evidence is a huge block of hard sandstone, shaped like a shallow shoe box, that Is in the Geo- logical Museum in London. This was balanced across a steel beam about three feet from the floor in the year 1909 By 1930 its two ends had bent down to rest on that floor. Incidentally, there is a kind of sandstone called Carolinite that, when cut into thin slabs of about the size of a pocket notebook, can be bent back and forth as though it were paper This is an odd phenom- enon, and it is due to the loose arrangement of the molecules of which the stone is composed. Then it must not be forgotten that earth tides, causing an expansion and contraction of all surface rocks, flow round and round the earth evei7 day just as ocean tides do through the water. THE DEATH PITS Another product of crustal instability may be seen in the middle of the modern city of Los Angeles—the famous La Brea Tar Pits (the word hrea means "bitumen" in Spanish). These are great funnels in the earth filled with bituminous pitch or asphalt that keeps welling up from below. The material has a consistency somewhere between firm taffy and frozen butter. It may be cut or dug out with a sharp, strong instrument and the hole will always fill up again. It is black and of smooth texture. Through- out the soil in adjacent areas may be found small patches, lumps. In Ice Age times, the famous Tar Pits of Los Angeles, now in a city park, were traps of crude- oil seepage in which hundreds of animals died.
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