16 SEASONAL DEPOSITION IN AQUEO-GLACIAL SEDIMENTS. 
was discovered about six inches thick. This was followed by a sandy-silt layer 
three feet thick and then another layer of clay not quite as thick as the first clay 
layer. (See Plate 4, fig. 1). The alternating layers of clay and sand continued 
upward for about twenty-five feet with a most remarkable and regular diminu- 
tion in the thickness of both the fine and coarse components. At the top of 
this deposit of regularly banded clays the combination of a fine and coarse 
component did not measure more than three fourths of aninch. On account of 
the abrupt ending of the layers at this point, at the level of the surface of one 
of the river terraces, there is no doubt but that a great many of the banded 
layers have been eroded in the cutting of the terrace. (See Plate 5, fig. 1). 
In a case like this there can be very little doubt but that the regular thinning 
of the layers was due to a recession of the ice front. The retreat was rapid. 
The thicknesses of the coarse or summer components are always much greater 
than the fine or winter components. This would indicate that interglacial con- 
ditions were possibly in force at this time and place. I observed no contorted 
zones due to grounding bergs, so it is evident that the main path of drifting 
bergs was not at this place. The sediments also from the bottom to the top 
of this deposit indicate very slowly moving currents and not such as would be 
found in the main current of the lake. 
About seven miles south of Wells River and a mile north of Newbury, 
Vermont, there is an exposure of well-banded clay and very fine sand. The 
thinnest layers are at the bottom and the stratification grows thicker upward. 
The regularity of interval is very marked. The coarse components are slightly 
thicker than the fine. About fifteen feet only of the material can be seen. At 
the bottom the two components average about two and one half inches, an inch 
for the fine and an inch and a half for the coarse. Near the top of the section 
the yearly deposit averages about four inches and about three feet below the 
top there are irregular strata of sand and gravel with no definite seasonal bands. 
The change from thin to thick components in the deposits at this place with 
the irregular coarse material at the top would indicate advancing ice. That 
the fine and coarse layers are almost of the same thickness would also indicate 
cold conditions. The melting of large glaciers in a warm period should yield 
a large summer deposit and a small winter deposit, as exemplified in the banded 
clays near Hanover, described above. No till was found above these banded 
deposits, and no contorted zones were observed. It is probable that the ice 
did not at this time reach so far south as this locality and was simply a local 
advance of short duration. 
SaaS 
