BANDED CLAYS. 29 
Farther on (loc. cit. p. 188) he notes: 
“Tt is doubtful if the regular banding of larger bodies of clay miles beyond a delta 
margin with an even lamination of sandy partings can be so explained.” WoopDwortTH, 
1905, p. 183. 
In very shallow water the swinging of the stream across the delta-fan 
would produce a banded structure of alternating coarse and fine materials in 
the manner described by Woodworth. In the case of a glacial stream emerging 
into deep water, however, conditions would be different. The sediment-laden 
current would spread out to right and left and assume the shape of a fan itself. 
The place of emergence of the stream would shift with the retreat or advance 
of the ice, so that a very extensive fan of any description could not often be 
built up at any one place. Although in shallow water banding of a discon- 
tinuous and rather irregular nature is often due to the swinging of a stream 
across a delta, the cause of the regular banding discussed in this paper is princi- 
pally alternately quiet and moving water. 
In Rhode Island some laminated clays are well exposed in the town of 
Barrington in the clay-pit of the Barrington Steam Brick Co. This locality 
was described by Woodworth (1896) and later by Fuller (1899). The clays here 
are reported to be 60 feet thick. In November, 1917, about fifteen feet only of 
the upper part of the deposit could be seen at the workings in the pit. The 
laminae at the bottom of the exposed section and for about seven feet upward 
have a very regular interval of about one fourth of an inch. The coarse com- 
ponents are thick relatively to the fine, the latter not being over one fourth 
as thick as the former. The units increase in thickness regularly upward and 
at the top of the clays are an inch and a half thick. Sands lie on these upper 
layers and here and there may be seen lumps of clay mingled with the sand 
in positions which seem to indicate dislocation by moving ice. In places the 
clays exhibit large folds for the seven or eight upper feet of the deposit, and 
in some of these depressions peat several feet thick has formed. The clays 
also appear to be cut off on top in some places. From a number of well-glaciated 
pebbles found in the uppermost part of the deposit and the large glacial boulders 
found on the surface not far away, it is evident that ice advanced over this 
region after the clays were laid down. The thickening of the seasonal deposits 
upward appears to indicate an approach of the ice. Among all the different 
causes for the thickening of the seasonal deposits it is difficult to think of any- 
thing which fits this case so well as ice advance. It is possible that these clays 
are older by many years than the ice advance indicated by the folds; irregular 
