310 The Ainerican Geologist. November, i898 
shown, have given rise to these chemical pecuHarities, they 
must have come from the waters themselves, and primarily 
from the sky, either as volcanic tuffs or as precipitations from 
the surrounding atmosphere. It is reasonable to presume 
that the early volcanic products would be like the early crust, 
ferro-magnesian, and not alkaline. We are to look for these 
elements, then, rather to the atmosphere in its normal condi- 
tion — i. e., in its condition normal to the Archean age, just fol- 
lowing the congealing of the first crust. The question is then 
one that is chemical and physical, and is resolved into an 
inquiry whether the world's great stock of potassium was 
stored up in the Archean because of the operation of the 
Laplacean hypothesis in its progressive unfolding. It is a 
question which leads into an examination of the volatile point 
of potassium and into its chemical properties and its probable 
activities under Archean conditions, and as such it is beyond 
the scope of this paper. 
GLACIAL THEORIES- COSMICAL AND 
TERRESTRIAL. 
By E. W. Claypole, Pasadena, Cal. 
The enigma of the Ice age is still unread. When the gen- 
eral scepticism which greeted the promulgation of the doc- 
trine had given place to acceptance the cause of so portentous 
an interruption of geological evolution became a topic for in- 
vestigation of the first importance. And it has proved to be 
a topic of extreme difficulty. While it is now impossible to 
deny the occurrence of glacial conditions, probably several 
times repeated during the recent history of the earth, yet it 
has thus far been impossible to discover any sufficient or satis- 
factory cause for so great and widespread a lowering of the 
temperature over much of the temperate zones — -a lowering 
that was sufficient to bring Arctic conditions almost down to 
the latitude of 35° in North America, and to 45° in Europe, 
to cover the mountainous regions of the globe everywhere 
with thick sheets of snow and ice and to extend the antarctic 
cold to limits only a little less wide than those over which the 
northern glacial winter prevailed. 
