A guide to geology / [John Phillips].

  • John Phillips
Date:
1835
Catalogue details

Licence: Public Domain Mark

Credit: A guide to geology / [John Phillips]. Source: Wellcome Collection.

    73/198 (page 53)
    misunderstood. We are well assured of the length of time required for the growth and maturity of or- ganic beings; when, therefore, a single bed of stone only a few inches thick is found to contain a given species of shell, in every variety of magnitude, from the embryo to the full-grown or aged individual, all the specimens having evidently been enveloped quietly on die bed of the sea, and no bed either above or below for 100 yards or more containing any such shells, the conclusion seems certain that even for the accumulation of this one bed of stone the lifetime of that species of molluscous animal was required. Such a case occurs in die coal district of Yorkshire, w'here a bed of shale only a few inches thick, but extending for many miles, contains Ammonites Listen in every stage of its growth; but that shell does not occur above or below, through a great thickness of strata. In some cases whole rocks are literally composed of zoophytes, so as to resemble a modern coral reef, or of shells of many kinds. The extensive strata of coal are derived entirely from immense accumula- tions of vegetables, and sometimes no less than fifty consecutively deposited strata of this kind extend over a hundred square miles and more. Strata which contain certain tribes of organic re- mains alternate with others which inclose none, or quite different races. Strata full of marine exuviae are separated by others full of trees swept down from the land; and thus we are furnished with evidence of inter- mitting activity among the agents of ancient nature. 59. It seems unnecessary to accumulate more evi- dence in order to obtain an unanimous verdict from all impartial readers that the length of time occu-