PALEONTOLOGICAL GEOLOGY 
325 
temperature for the oceans; so that it would be hazardous to guess 
at an average temperature of the Permian ocean. 
If it is assumed that Permian glaciation withdrew sufficient 
water from the oceans to lower the surface 600 feet over its 
entire area, granting the area to have been 139,235,000 square 
miles (the same as the present area) this amount of lowering 
would be ten times that estimated by Daly (50 to 60 feet) for the 
Pleistocene glaciation. The volume abstracted to form ice would 
be 17,412,00 cubic miles or about five and one-half per cent 
of the total volume; that is, approximately one-twentieth of the 
total volume. The latent heat of ice is 80 calories per gram or 
5.39 times 10 to the 24th power calories. If all the heat for 
melting this ice came from the ocean then the temperature of the 
ocean would be lowered 5.20 X 10^^-^ 1.24 X 10^^ which equals 
42 degrees. Inasmuch as the remaining nineteen-twentieths of 
the ocean was above zero the mixing of 19 volumes with one 
volume at zero would result in a lowering of .05 for each degree 
centigrade of difference of temperature, probably making in all 
less than 5 degrees centigrade. 
If the Permian glaciation withdrew from the ocean an amount 
of water only equal to that withdrawn by the Pleistocene glacia¬ 
tion this figure of temperature change would be .5 degrees centi¬ 
grade. These figures are based on the ocean supplying all the 
heat necessary to thaw the ice, during which time the ocean 
neither received nor radiated heat energy. It is obvious from the 
areal distribution, as well as the character of the deposits of con¬ 
tinental ice-sheets, that very little of the ice could have melted in 
contact with ocean waters, and where this was the case the sea 
was not the sole source of heat. In other words probably 95 per 
cent of the ice-sheet melted in contact with either the atmosphere 
or the land, and the resulting water flowed through rivers of great¬ 
er or less length to the sea. The lowest temperature of this water 
-could not have been below zero centigrade, the equilibrium tem¬ 
perature of ice and water. 
If we accept Clark’s estimate of the volume of the ocean at 
302,000,000 cubic miles, which is somewhat smaller than Murray- 
Hjort’s estimate, and the annual discharge of all rivers into the 
oceans as 6524 cubic miles, it would take about 44750 years to 
replace the entire volume of water iffi the oceans. However, 
