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SEASONAL BANDING IN GLACIAL CLAYS. 11 
that the mass of the coarse material of these deposits has been brought in from the sides and 
moved but little downstream, to indicate a low pitch for the valley during the time of the 
glacial stream. * * * 
“The considerations of the preceding section afford data for a calculation of the time 
occupied by the deposition of the clays, which is presented as interesting rather than specially 
valuable. If we take the clays exposed in the south of the Camp Meeting cutting and in 
the river bank adjacent, a thickness of 72 feet is exposed down to the water level, which would 
give, at an average of two-fifths of an inch per layer, 2,155 years. If we take the boring at 
the Northampton bridge, 113 feet, we have 3,390 years. As these two neighboring sections 
are measured, the one up and the other down, from the river level, we may add these two 
numbers to obtain a maximum time for the deposition of the clays — 5,545 years.” EMER- 
son, 1898, p. 706, 707. 
A few years, 1894, after Emerson’s first (1887) description of his theory 
of seasonal deposition in glacial clays, Taylor without knowledge of the work 
of de Geer and Emerson came to similar conclusions. Concerning the glacial 
clays and silts at Bracebridge, Ontario, Taylor wrote: 
“Take, for example, the silt beds at Bracebridge. The whole set of phenomena at 
this place is extremely instructive. The laminations of clay and silt are associated in pairs 
which are almost without exception about half an inch in thickness. On weathered surfaces 
the principal part of each layer is a greenish gray clay, and this is separated from the next 
layer of clay in each case by a layer of white silt, an eighth to a sixteenth of an inch in thick- 
ness. There are some variations in the composition of the deposit at each locality, but they 
are confined chiefly to varying proportions of the two materials. Ina few places I found the 
clay almost absent and the silt layer thicker than usual. In other places the variation was 
reverse of this. It seems plain enough that the silt and the clay must represent two slightly 
different conditions of sedimentation; and the orderly way in which the layers alternate 
shows that a layer of silt and a layer of clay taken together constitute one complete round of 
change. This points to recurrence and almost certainly to periodicity. Tides, storms, and 
the annual round of the seasons, are the only recurrent variations liable to affect sedimenta- 
tion. Of these the tides and the seasons are periodic, but storms are irregular. Neither 
tides nor storms afford a satisfactory explanation. For the one is much too short in its 
period, and the other too irregular. It seems impossible that the pairs of layers can represent 
anything but annual periods of deposition, and if this be the case several important conclu- 
sions follow. Considering the great thickness of the whole deposit, the length of time which 
must be allowed for its formation can hardly be less than several thousand years. Indeed, 
if we suppose the laminations to be uniform, and the maximum depth of the whole original 
deposit to have been 100 feet, the time of deposition would be about 2,500 years. And this, 
it should be noted, would be not the whole time of the submergence, but only the time during 
which the conditions of still-water sedimentation existed at that level, not counting the two 
periods unfavorable to this kind of sedimentation, one as the water was rising and the other 
as it was receding, during both of which shallow water conditions prevailed.” 'Taytor, 
1894, p. 288, 289. 
In 1902 Coleman, describing the laminated clays of the Don River inter- 
glacial beds, wrote: 
“The peaty clays often show fine lamination with thin silty layers at intervals of 13 
or 2 inches, the latter often charged with spruce needles, beetles’ wings, etc. These 
