i8o T. C. CHAMBERLIN 



known to have occurred at a late geological period, and so it was 

 natural to assign it to an advanced stage of cooling of the earth. Fur- 

 ther, it was seen to be correlated with the great deserts and so the 

 phenomena of glaciation and of great aridity were thought to be 

 but the signs of a senile planet; the advance stages of the final 

 drying up and freezing up of the earth. Thus the sea and warmth 

 were habitually associated in geologic thought about the earlier 

 ages, while dryness and cold were close companions in the thought 

 of the later stages. 



Who first advanced the special doctrine that the mild climates 

 of the geologic ages in high latitudes were caused by an extension 

 of the sea, it would be venturesome to state. Very likely it grew 

 up gradually by little transfers of the earlier thought of a universal 

 warm sea to the special cases of warm climates in high latitudes as 

 evidences of these came successively into notice. At any rate, if the 

 doctrine is to be put on the shelf, it is perhaps just as well not to 

 lay stress on its parentage or on its clientele. It was a common 

 doctrine, and quite unchallenged, when I first became interested 

 in paleoclimatic subjects; I accepted it as standard doctrine and 

 taught it. It was only when I had occasion to inquire seriously 

 into geoclimatic problems that doubt as to its verity arose. 



To avoid ambiguity let it be noted at the outset that the question 

 here raised is specific and definite. Would an extension of the sea 

 in high latitudes cause or tend to cause a warm climate in and of 

 itself irrespective of superimposed factors ? Of course the extension 

 of a warm sea would favor a warm climate, and the extension of a 

 cold sea, a cold climate. Our question is whether the replacement of 

 a normal land surface by a normal sea surface in the high latitudes 

 would thereby, irrespective of special conditions, tend to give a 

 warmer climate. Let us first look for concrete evidence, and later 

 turn to the theory of the case. 



COMPARISON OF THE CLIMATES OF THE WATER-HEMISPHERE 

 WITH THOSE OF THE LAND-HEMISPHERE 



The distribution of sea and land is fairly well suited for this 

 inquiry. The Southern Hemisphere is very largely covered by 

 the ocean; its land surface is not only much smaller than the sea 



