274 CONTEMPORANEITY OP STRATA AND THIS 



If we take into consideration tlie converse of this, namely: how 

 beds, which we know to be contemporaneous in the strict sense of 

 the word, necessarily contain, in many cases, wholly different fossils, 

 we shall be further convinced of the propriety of the views here 

 advanced. If one could suddenly remove the sea from the earth, we 

 should find at various points thus rendered accessible, deposits of 

 different kinds, now concealed from us by the ocean, or only partially 

 known by soundings or dredgings. Thus, where now rolls the 

 Pacific Ocean, we should find vast accumulations of calcareous 

 matter in the form of coral rock, and coral reefs. In high northern 

 and in low southern latitudes, we should find great deposits of fine 

 mud and sand, with angular blocks of stone; the whole derived from 

 the great ice-fields of Arctic and Antarctic lands. Over wide areas, 

 again, of the deep Atlantic, we should meet with an impalpable 

 calcareous mud or " ooze." All these different deposits are obviously 

 and necessaiily "contemporaneous," not onl}'" in the loose geological 

 acceptation of the word, but in its strictest sense. In spite of this 

 fact they loould not contain the same fossils, and indeed, they would 

 be characterised by organic remains which would be wholly different 

 in each case. The coral reefs of the Pacific would be mainly charac- 

 terised by the abundance of the remains of corals, though they 

 would also present the exuviae of other tropical forms of animals, 

 especially Bi-achiopods and Echinoderms. The glacial miid of northern 

 seas would contain the remains of arctic Molluscs, along with such 

 other animals as delight in severe cold. Lastly, the " ooze" of the 

 deep Atlantic would contain innumerable Foraminifera, along with 

 siliceous sponges, sea-urchins, and Crinoids. We learn from this, 

 therefore, that contemporaneous deposits not only do not necessarily 

 contain the same fossils, but that, if widely separated geographically, 

 they may be characterised by wholly dissimilar assemblages of 

 organisms. 



It may happen, again, as pointed out by Sir Charles Lyell, that 

 deposits belonging to different geographical provinces may, as regards 

 space, be extremely close together, and as regards time, may be 

 actually contemporaneous, and yet may not contain any fossils in 

 common, or only a very few. If, for example, any sudden upheaval 

 were to lay bare what is now the floor of the Red Sea, together with 

 that of the Mediterranean, we should find each to be occupied by 



