SEASONAL DEPOSITION IN AQUEO-GLACIAL 
SEDIMENTS. 
_1.. INTRODUCTION 
ALTERNATIONS between coarse and fine sediments in a regular rhythmical 
banding have been noted by geologists for many years. To the different types 
of banding, various causes have been ascribed. ‘That seasonal variation in 
deposition does not account for all kinds of banding is perfectly clear. In this 
paper only the banding in clay sediments associated with glacial deposits will 
be discussed. It is suspected that the banding in many slates, without associ- 
ated glacial deposits, may be due to variations in seasonal deposition, but until 
the banded glacial sediments have been thoroughly studied, and the criteria 
fully determined, it is inadvisable to discuss these other well-banded sedi- 
mentary rocks. 
I wish to acknowledge my appreciation of the helpful advice and encourage- 
ment given me in this work by my colleagues, Profs. W. W. Atwood, J. B. 
Woodworth, and E. C. Jeffrey. Professor Atwood carefully examined the 
slate at Squantum with me in November, 1915, and also visited the section 
of the clays at Woodsville, N. H. Professor Woodworth very kindly read my 
manuscript and gave invaluable criticism. To Professor Jeffrey I am much 
indebted for the photomicrographs, Plate 16. Mr. Frank B. Taylor spent two 
days with me on the Squantum tillite and slate formations, and favored me 
with his opinion on the problem of seasonal banding in the slate at Squantum. 
2. LITERATURE ON SEASONAL BANDING IN GLACIAL CLAYS 
For many years geologists have noted the strikingly even lamination of 
glacial clays.- Some observers have attributed such regularity to seasonal 
deposition, but only recently have geologists felt confident that this regularly 
alternating deposition of coarse and fine sediment could be used as a means 
of recording past time. 
