CRITERIA FOR AQUEO-GLACIAL SEDIMENTATION. 31 
4, CRITERIA FOR THE STUDY OF AQUEO-GLACIAL 
SEDIMENTATION. 
In studying the seasonal banding in glacial sediments, the differences and 
irregularities in the banding of the various exposures demand explanation. With- 
out some actual record of the formation of the layers it is impossible to do more 
than offer hypotheses or theories. The best way of all to determine the condi- 
tions which existed in the bottoms of the areas of deposition, would be to probe 
the deposits now forming in some of the existing glacial lakes and study the 
samples thus taken. It would also be possible to collect deposits as they form, 
during a period of several years. In this latter way it would be possible to 
identify each deposit with its year. As the weather conditions for that year 
and place would be recorded, the study of the layers with regard to the weather 
would be most profitable. Some such procedure as this would seem to be 
desirable if this subject of seasonal deposition in deposits is to rest on an abso- 
lutely secure scientific basis. In the meantime, all that can be done is to com- 
pare seasonal bandings with other bandings and in the case of ancient bandings 
in slates and sandstones, to compare them with known seasonal bandings in 
more recent deposits. 
1. Facrors DETERMINING THE WIDTH AND OTHER CHARACTERS OF REGULAR 
BANDING. 
A. In considering the thicknesses of seasonal deposits the amounts of 
sediment which come from glaciers in various parts of the world must be 
mentioned. Other things being equal, the size of a glacial stream depends 
on the size of the glacier. In Alaska, for example, the streams from the 
large glaciers are large and the amount of sediment carried out each year 
is tremendous. Reid (1895) estimated that 15,600,000 cubic meters of sediment 
was the yearly product of the Muir glacier, from all its glacial streams. The 
annual product of the Unteraar glacier, in Switzerland, is only 6,000 cubic 
meters. 
The amounts of sediment in the glacial waters are also very variable. The 
Muir glacier water has a very great amount of sediment in comparison with 
most glaciers. Wright (1891) found 12.12 grams per liter and Reid 12.98 
grams per liter. Reid cites several cases as follows:— The water from the 
