194 



Dr. Carpenter's Preliminary Report 



[Dec. 17, 



"cold area/' our Geologist would find a hill some 1800 feet high, covered 

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

 rich in remains of Animals belonging to a more temperate province (§ 13) ; 

 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 contemporaneous but dissimilar climates, separated only by a few 

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

 sible to exaggerate the importance of these facts, in their Geological and 

 Palaeontological relations, especially in regard to those more localized 

 Formations which are especially characteristic 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-tem- 

 perature, depending upon deep oceanic currents, was not the chief de- 

 termining cause of that remarkable contrast between the Faunae of different 

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

 and variety of the Fossils of one localhV^, and their scantiness and 

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

 mordial Zone" of Barrande is compared with its equivalent in North 

 Wales. — Further, in the case of those Calcareous deposits which owe their 

 very existence to the vast development of Organisms that possessed the 

 power of separating Carbonate of Lime from the ocean-waters, temperature 

 may be pretty certainly assumed to be the chief condition, not merely of 

 the character of the Animal remains which those formations may include, 

 but of the very production of their solid material. 



IX. How important a light is thrown by the facts we have brought into 

 view on those changes in the Marine Fauna of any particular area, which 

 cannot be referred to changes in its own geological condition, need scarcely 

 be pointed out. As there must have been deep seas in all Geological 

 epochs, so there must have been varieties in Submarine Climate at least as 

 great as those we have discovered, depending upon those Equatorial and 

 Polar Currents whose existence has been shown to be a Physical necessity. 

 Hence it is obvious that since changes in the direction of such opposing 

 currents must have been produced by any upward or downward move- 

 ment of the sea-bottom (as in the areas of elevation and subsidence 

 marked out by Mr. Darwin in our existing seas), a considerable modifica- 

 tion, or even a complete reversal, of the Submarine Climates of adjacent 

 areas might have been consequent upon alterations in the contour of the 

 land, or in the level of the sea-bottom, at a great distance. The effect of 

 such a modification of Temperature upon the respective Faunae of these 

 areas would probably depend upon the rate and degree of the change. If 



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 for. 



