é 
Mesozoic and Cenozoic Geology and Paleontology. 199 
Manistee, where it does not generally reach more than 4 or 5 feet above 
the river, although in one place it was found 10 feet thick. It is very 
tough, and generally flesh colored, but in one instance it was perfectly 
white. There were observed, in several localities, rather coarse pebbles 
of limestone, and even flat stones intermixed with the upper layer of | 
clay, near its contact with the sand. 
He described the terraces on the island of Mackinac and the neigh- 
boring coasts, on the west coast, and at Pointe St. Ignace and Gros 
Cap on the north coast of Lake Michigan, which vary in height from 
20 to 130 feet. But the terraces are not found farther west on the 
north shore of Lake Michigan and Green bay, nor in the vicinity of 
the Menomonee and Manistee. 
Mr. Charles Whittlesey,* said of the terraces bordering Lake Erie, 
that the first ridge, or that nearest the lake, is known as the “ North 
ridge.” From Conneaut, in Ashtabula county, to Russelton, Huron 
county, a distance of 120 miles, the elevation of the ridge above the 
lake varies from 85 to 145 feet. The second ridge, from Kingsville, in 
Ashtabula county, to Ridgeville, in Lorain county, varies from 122 to 
168 feet above the lake. These ridges consist of coarse, water-washed, 
yellowish sand, or of fine gravel, principally the comminuted portions of 
the adjacent rocks. The rocky fragments are not generally worn per- 
fectly round, or oblong, as beach shingle is, but are more flat, with 
worn edges. There are mingled with the sandstones and shales that 
compose this gravel, scattered pieces of quartz, flint, granite, trappean 
“rocks, limestone and ironstone. The third and fourth ridges are a 
little higher, and composed of coarser material. 
In 1852, Charles Whittlesey+ described the drift in that part of Wis- 
consin bordering on Lake Superior, and lying between the Michigan 
boundary and the Brule river, and the sources of the streams flowing 
into Lake Superior from the south. He divided the drift into—Ist, 
red marly clay; 2d, bowlder drift, coarse sand and gravel. 
The red marly clay is a fine-grained, homogeneous marly sand, 
cemented by argil or clay, with well defined horizontal lines of lamina- 
tion or deposition; containing, but very rarely, pebbles of granitoid, 
trappose, sandstone, conglomerate, or slate rocks. This constitutes the 
shore or lake bluffs most part of the way from the Montreal to the 
Brule; the red sandstone, on which it rests, showing itself occasionally 
beneath. It is easily washed away in suspension by the waves, and 
* Am. Jour. Sci. and Arts, 2d ser., vol. x. 
t Owen’s Geo. Sur., Wis., Iowa, and Minn. 
