14 SEASONAL DEPOSITION IN AQUEO-GLACIAL SEDIMENTS. 
sandstone, alternating between layers of fine clay and sandstone, the latter often spotted 
with pebbles of vesicular basalt. The clay layers were generally about an inch in thickness, 
while the sandy layers were often a foot thick and seemed to represent the annual flood of 
the stream. The ripple marks, by the steeper slope of the ripple ridges, showed a south- 
westerly direction of flow. In one place the sandstone was cut by a basalt dike which proba- 
bly served as a feeder to some of the upper lava flows.” Frreuson, 1906, p. 126, 127. 
Those who have tried to explain the tillite at Squantum as of igneous 
origin should consult Ferguson’s paper. The mixture of volcanic and glacial 
deposits would puzzle anyone if these beds were consolidated. There is a 
very much greater mixture of volcanic and glacial beds in the Iceland deposits 
than in the rocks of the Boston basin. 
In 1913 Wilson (p. 104) described banded glacial clays in Quebec and con- 
sidered them to be due to seasonal deposition. 
In discussing the age of the Don River glacial deposits, Wright 1914, states: 
“A clue to the length of time during which Lake Warren continued to cover the border- 
ing land on the south side of Lake Erie is furnished by deposits recently uncovered by excava- 
tions at Fremont, Ohio. The sedimentary plain on which the city of Fremont is built lies 
below the 100-foot level of the lowest shoreline of Lake Warren. The sedimentary deposits 
consist of the material brought into Lake Erie by Sandusky River, which is spread out as a 
delta. The depth of these lacustrine beds is at least 25 feet. The thickness of the lamine, 
according to my measurements made in several excavations, is on an average one-seventh of 
an inch, making 84 to the foot, making a total of 2,100, which would be the number of years 
required for the accumulation on the supposition that each lamina represented an annual 
deposit. Whatever be the date, therefore, which we assign to the upper beach of Lake 
Warren, that of the Iroquois beach around Lake Ontario must be 2,000 years less. This, 
according to my calculation, would bring the date of the 200-foot shelf at Toronto at about 
10,000 years.” Wricut, 1914, p. 208, 209. 
