Elements of geology, or, The Elements of geology, or, The ancient changes of the earth and its inhabitants as illustrated by geological monuments elementsofgeolog00lyel Year: 1868 Ammonites BraikenHdgvi, Sow. Ostrea Marshii. \ rtat. size. Oolite, Scarborough. Middle and Lower Oolite, or ranging Inf. Ool., Dundry ; Calvados; &c. from Coral Bay to Cornbrash. Palceontological relations of the Oolitic strata.—Observations have already been made, p. 345, on the distinctness of organic remains of the Oolitic and Cretaceous strata, and at pp. 398 and 401 of the proportion of species common to the Up
Elements of geology, or, The Elements of geology, or, The ancient changes of the earth and its inhabitants as illustrated by geological monuments elementsofgeolog00lyel Year: 1868 Ammonites BraikenHdgvi, Sow. Ostrea Marshii. \ rtat. size. Oolite, Scarborough. Middle and Lower Oolite, or ranging Inf. Ool., Dundry ; Calvados; &c. from Coral Bay to Cornbrash. Palceontological relations of the Oolitic strata.—Observations have already been made, p. 345, on the distinctness of organic remains of the Oolitic and Cretaceous strata, and at pp. 398 and 401 of the proportion of species common to the Upper and Middle, and to the Middle and Lower Oolite. Betweenthe latter and the Lias there is a somewhat greater break, for out of 120 mollusca of the Upper Lias 13 species only pass up into the Inferior Oolite. Professor Ramsay has call- ed our attention to an important generalization not yet alluded to, name- ly, that there are at present wider breaks between some of our minor sub- divisions, and especially between the Inferior and the Great Oolite, palse- ontologically considered, than between what we generally regard as divisions of a higher order, such as the Lower, Middle, and Upper Oolites. Thus, for example, there are, according to Mr. Etheridge's tables, 518 species of mollusca known in ^he Great Oolite and 370 in the Inferior, and of these only 93, or about 12 per cent., are common to the two ; and, what is very remarkable, of 39 species of Cephalopoda known in the Inferior Oolite, only one passes upwards into the Great Oolite, namely, Belerftnites giganteus, and it has been questioned by some palaeontologists whether even this Belemnite has really been found in the Upper of the two formations. This distinctness of the Cephalopoda is the more striking, because both the Great and Inferior Oolites are calcareous formations, and we cannot, therefore, account for the difference of species by any marked dissimilarity in the nature of the sea-bottom. As to the intervening F
Size: 1803px × 1109px
Photo credit: © Bookworm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: archive, book, drawing, historical, history, illustration, image, page, picture, print, reference, vintage
