80 THE CANADIAN NATURALIST. [March 



a Cretaceous formation, including not only an extraordinary 

 abundance of Sponges, but a great variety of other Animal 

 remains, several of them belonging to the vrarmer Temperate 

 region, with the barren Sandstone whose scanty Fauna indicates a 

 widely different climatic condition, which he would naturally 

 suppose to have prevailed at a different period. And yet these 

 two conditions have been shown to exist simultaneoudy at corres- 

 ponding depths, over wide contiguous areas of the sea-bottom; in 

 virtue solely of the fact that one area is traversed by an Equa- 

 torial and the other by a Polar current *. Further, in the 

 midst of the land formed by the elevation of the " cold area,'' our 

 Geologist will find a bill of some 1800 feet high, covered with a 

 Sandstone continuous with that of the land from which it rises, 

 but rich in remains of Animnls belonging to a more temperate 

 province ; and might easily fall into the mistake of supposing 

 that two such different Faunae, occurring at different levels, 

 must indicate two distinct climates separated in time, instead 

 of indicating, as they have been shown to do, two contem- 

 poraneous but dissimilar climates, separated only by a few miles 

 horizontally, and by 300 fathoms vertically. — It seems scarcely 

 possible to exaggerate the importance of these facts, in their 

 Geological and Palaeontological relations, especially in regard to 

 those more localized Formations which are especially character- 

 istic of the later Geological epochs. But even in regard to those 

 older Rocks, whose wide range in space and time would seem to 

 indicate a general prevalence of similar conditions, it may be 

 suggested whether a difference of bottom-temperature, depending 

 upon deep oceanic currents, was not the chief determining cause 

 of that r. markable contrast between the Faunae of different areas 

 in the same Formation, which is indicated by the abundance and 

 variety of the Fossils of one locality, and their scantiness and 

 limitation of type in another ; as is seen, for example, when the 

 " Primordial Zone '' of Barrande is compared with its equivalent 



• It may be said that the asserted existence of these Currents is a 

 mere hypothesis, until an actual movement of water in opposite direc- 

 tions has been substantiated. But, as Prof Buff has pointed out, 

 the existence of such deep currents is a necessary consequence 

 of the difference of surface-temperature between Equatorial and Polar 

 waters; and those who raise the objection are consequently bound 

 to offer some other conceivable hypothesis on which the facts above 

 stated can be accounted far. 



