. Elements of geology. Geology. PART II. CHAPTER XIV. 177 Older Pliocene Strata English Crag. as in the colder regions. A large volute, called Voluta Lam- berti, (Fig. 135.) may seem an exception ; but it differs in form from the volutes of the torrid zone, and may, like Fig-. 135. the large Voluta Magellanica, have been extra- tropical. When I first submitted the shells of the crag to M. Deshayes, in 1829, he recognized their general resemblance to the fauna of the German ocean, and determined that out of 111 species there were 45 identical with those now living. Dr. Beck, on the other hand,
. Elements of geology. Geology. PART II. CHAPTER XIV. 177 Older Pliocene Strata English Crag. as in the colder regions. A large volute, called Voluta Lam- berti, (Fig. 135.) may seem an exception ; but it differs in form from the volutes of the torrid zone, and may, like Fig-. 135. the large Voluta Magellanica, have been extra- tropical. When I first submitted the shells of the crag to M. Deshayes, in 1829, he recognized their general resemblance to the fauna of the German ocean, and determined that out of 111 species there were 45 identical with those now living. Dr. Beck, on the other hand, who has since seen much larger collec- tions, considers that almost all the species are dis- tinguishable from those now living, and this subject is still under discussion. Valuta LamUrti, Jt has been asked whether, as the upper and young individ. j^^^^ ^^^^ Suffolk differs greatly in mineral composition and fossils, they may not belong to two different ter- tiary periods. To this I may reply, that the general character of the shells is the same, and by no means leads to such a con- clusion. The two deposits may have been going on contempo- raneously under different geographical conditions in the same sea. One region of deep and clear water, far from the shore, may have been fitted for the growth of certain corals, echini, and testacea ; while another shallower part nearer the shore, and more frequently turbid, or where sand and shingle were occa- sionally drifled along, may have been favourable to other species. After this, the region of deep and tranquil water becoming shal- low, or exposed to the action of waves and currents, a formation like the coralline crag may have been covered over with sandy deposits, such as the red crag, and many fossils of the older beds may have been washed into the newer strata. If a considerable lapse of time intervened in a particular spot between the conver- sion of a deep sea into a shoal, some small change in organic life may have taken plac
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Keywords: ., bookauthorlyellcharlessir17, bookcentury1800, booksubjectgeology
