72 Kansas Academy of Science. 



20° colder than now, and the summers twenty-two days 

 shorter and much hotter. (See Le Conte's Elements, p. 614.) 



As a first objection, the winter temperature at Des Moines, 

 Iowa, which city, as is stated above, was in the glaciated 

 region, is about 16° above zero, and the summer average is 

 77°. Now the winter average in glacial times, according to 

 the above theory, was 4° below zero and the summer average 

 much hotter than now. This would not give a glacial climate 

 at that city, for even now the average yearly temperature for 

 St. Petersburg is much lower than that of the site of the city 

 of Des Moines in glacial times, to use the above figures. Not- 

 withstanding that, St. Petersburg does not enjoy perpetual 

 winter. This theory does not also account for the long con- 

 tinuation of the glacial epoch, which is supposed to have lasted 

 160,000 years (see Le Conte's Elements of Geology, p. 617), 

 because within this period the equinoxes would have made 

 more than seven complete precessions, 26,000 years being a 

 precession (Ly ell's Principles of Geology, vol. I, p. 275), and 

 would therefore have been in complete opposition to a glacial 

 climate more than seven times during the epoch. 



To meet the many objections in Croll's theory, Mr. Wallace 

 combines all the above-mentioned theories in one and says 

 that the glacial epoch was due to the combined influence of 

 aphelion winter, maximum eccentricity of the earth's orbit, 

 and northern elevation. (See Le Conte's Elements of Geology, 

 p. 616.) To this theory there are many objections. Croll says 

 that the highest-latitude northern regions were not elevated 

 in that epoch, but were lower then than now, the elevation 

 theory only being used as a hypothesis to account for the cold. 

 (Climate and Time, p. 391.) 



H. B. Norton also agrees with Mr. Croll in believing that 

 northern elevation of land did not then exist. His remarks 

 on the subject are as follows : 



"When we come to study the cause of these phenomena (the 

 phenomena of the ice age) we find many perplexing and con- 

 tradictory theories in the field. A favorite one is that of 

 vertical elevation. But it seems impossible to admit that the 

 circle inclosed within the parallel of 40° — some 7000 miles in 

 diameter — could have been elevated to such a height as to 

 produce this remarkable result. This would be a supposition 

 hard to reconcile with the present proportion of land and 

 water on the surface of the globe and with the phenomena of 



