462 Sayles — Dilemma of Paleoclimatolo gists. 



Then again we are not sure just how much heat the 

 radioactive oozes on the ocean floor generate. Joly 17 

 found that the red clay and radiolarian ooze exhibit much 

 radioactive substance, this in the case of the red clay 

 being over ten times as much as in average continental 

 rocks. Murray says again in regard to a rise in tempera- 

 ture of the bottom waters : 



"This rise of temperature has also been attributed to decom- 

 posing organic matter and to radioactive matter in the deposits 

 at the bottom. "Whatever may have been the cause we certainly 

 found a similar slight rise in the temperature of the deepest layer 

 on several subsequent occasions during our cruise." 



We do not know how thick the red clay is, but we do 

 know its great extent and its great radioactive content. 

 All the bottom oozes have high radioactivity. Is it not 

 possible that these self -heating deposits prevent so great 

 a loss of heat from the underlying rocks and thus con- 

 serve considerable heat which would otherwise be lost to 

 the waters ? If such a conservation of heat were possible, 

 instead of a greatly depressed thermal gradient, due to 

 the cooling of the waters, might we not have a tempera- 

 ture of about 680 degrees F. in absolute units under the 

 oozes? Possibly the temperature might be higher than 

 680 degrees F., for according to recent observations in 

 many deep borings the thermal gradient often increases 

 markedly after passing the 5,000-foot level, although in 

 some cases the reverse of this is true. 



Now as to the second question. What would the tem- 

 peratures of our earth be without the polar ice! If it is 

 true that the oceans, with a constant supply of ice water 

 from the polar regions, receive a negligible amount of 

 heat from the earth — and this has not been proved — the 

 cold water would cool off the earth under the oceans to a 

 considerable extent and thus lower the geotherms. Per- 

 haps this is the case, but there is little evidence for such a 

 conclusion. If the polar ice was melted away the heat 

 from the ocean bottoms might warm up the ocean waters 

 considerably. What would be the result of this combina- 

 tion of earth heat and sun heat on our climates ! 



•At the present time the oceans and the seas cover about 

 139,686,000 square miles and the lands are estimated at 

 about 67,254,000 square miles. In comparison with some of 



