. Elements of geology. Geology. PART II. CHAPTER XXII. 269 Horizontal Silurian Strata. Fig. ./J. Simmsii, portion of the shell at a, Fig. 281., natural size, showing the tube and its radii within the siphuncle. vered at Castle Espie, in the county of Down, in Ireland. (See Figs. 281, 282.) Silurian strata occasionally horizontal.—The Silurian strata throughout a large part of the province of Skaraborg, in the south of Sweden, are perfectly horizontal; the different subor- dinate formations of sandstone, shale, and limestone, occurring at corresponding heights in hills many leagues distan
. Elements of geology. Geology. PART II. CHAPTER XXII. 269 Horizontal Silurian Strata. Fig. ./J. Simmsii, portion of the shell at a, Fig. 281., natural size, showing the tube and its radii within the siphuncle. vered at Castle Espie, in the county of Down, in Ireland. (See Figs. 281, 282.) Silurian strata occasionally horizontal.—The Silurian strata throughout a large part of the province of Skaraborg, in the south of Sweden, are perfectly horizontal; the different subor- dinate formations of sandstone, shale, and limestone, occurring at corresponding heights in hills many leagues distant from each other, with the same mineral characters and organic remains. It is clear that they have never been disturbed since the time of their deposition, except by such gradual movements as those by which large areas in Sweden and Greenland are now slowly and insensibly rising above or sinking below their former level. The ancient limestone and shale also of the Canadian lake district before mentioned, are for the most part horizontal. These facts are very important, as the more ancient rocks are usually much disturbed, and horizontality is a common charac- ter of newer strata. Similar exceptions, however, occur in re- gard to the more modern or tertiary formations which, in some places, as in the Alps, are not only vertical, but in a reversed position. These appearances accord best with the theory which teaches that, at all periods, some parts of the earth's crust have been convulsed by violent movements, which have been some- times continued so long, or so often repeated, that the derange- ment has become excessive, while other spaces have escaped again and again, and have never once been visited by the same kind of movement. Had paroxysmal convulsions ever agitated simultaneously the entire crust of the earth, as some have ima- gined, the primary fossiliferous strata would nowhere have re- mained horizontal. X*. Please note that these images are extracted from scanned p
Size: 1989px × 1256px
Photo credit: © Paul Fearn / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorlyellcharlessir17, bookcentury1800, booksubjectgeology
