F. H, KnowUon — Evolution of Geologic Climates. 189 



The question of oceanic temperatures may be consid- 

 ered. On this point Schuchert says : 



''But what Knowlton actually holds is . . . that the tem- 

 perature of the oceans was everywhere the same without 'wide- 

 spread effect on the distribution of life. ' ' ' 



A ^'careful reading" of my paper, such as Schuchert 

 says he gave it, discloses that what I actually said was as 

 follows : 



"It now seems to be settled beyond serious question that the 

 waters of the early oceans were warm — in fact that they were not 

 permanently cooled as they are now until the approach of the 

 Pleistocene. This does not necessarily mean that there may not 

 have been fluctuation in their temperature from time to time, for 

 there doubtless was; but, taken by and large, the oceans were 

 warm from the equator to the poles. On this point Ulrich says : 

 'Taking the geologic marine record, as preserved in the fossil- 

 iferous rocks from the Cambrian to the Tertiary, it suggests 

 equable, mild, almost subtropical climates over the whole North- 

 ern Hemisphere in all the ages represented. ^ 



' ' Ulrich also adds that there is undoubted evidence, notably in 

 the early Cambrian, and early in the Pennsylvanian, when 'frigid 

 conditions occurred, at least locally.' This is the very crux of 

 the matter, for it seems clear that while there are undoubted 

 evidences of glaciation, they were, at least for the most part, so 

 very local in their effect that they seem to have made very little 

 impress on the temperature of the oceans, and hence on the 

 continuity and distribution of marine life." 



Professor Schuchert devotes several paragraphs to the 

 testimony of marine fossils in reflecting temperature 

 changes. Certain groups of animals were common in 

 the far north ^^and even in arctic water '^ during the 

 Silurian, Devonian, Pennsylvanian, and Jurassic, while 

 at other times they were greatly restricted or absent from 

 these regions. These, he thinks, ''can only mean temper- 

 ature influences, and that the northern waters were 

 frequently under 65° F.'' 



^'On the other hand," he adds, "when the lands are 

 largest and the marine faunas localized in small sea-ways 

 and not widely accessible to the paleontologist, where 

 are the cosmopolitan faunas and the larger forms?", etc. 



This seems a rather futile question to ask, for if the 

 faunas were confined to the small water-ways when the 

 continents were emergent, there was little for them to do 

 but back off into the deeper oceanic waters, where the 



