Xll 
cent beach lies upon the shore, and is not usually more than thirty feet high, 
but at Michigan City, Ind., the hills of blown sand, which form a part of this 
Eecent ridge, are one hundred and sixty feet high. The Upper beach begins 
on the lake shore at the village of Winnetka, in New Trier, and running 
southwest it strikes the Desplaines river at Eiverside, about eleven miles 
from the lake. Between this village and the Summit Station on the south 
side of the river, is an ancient outlet of the lake through which the waters ran by 
way of the Desplaines and Illinois rivers finally into the Gulf of Mexico. The 
Upper beach continues down the north side of the river till it passes out of the 
county. South of the river, the Upper beach surrounds a large area of unmodi- 
fied drift which was an island when the bay and the outlet existed. South of the 
island was another ancient outlet which united with the first westward of the 
island at a place near the river now called “The Sag.” The Upper beach, mark- 
ing the south shore of the bay and outlet, comes into the county on the south 
side of the Desplaines river, on the west line of the town of Lemont, and continues 
east and southward and passes out of the county into the State of Indiana near 
Lansing, on the Chicago and St. Louis E. E. The Middle beach begins on the 
shore of the lake near the north line of Evanston, and runs southward within the 
Upper beach and at a distance from it of four miles at the north end, to very near 
to it at the Village of Eiverside, where it disappears. From Summit Station on the 
south side of the Desplaines river, it runs eastward and southward around the 
small lakes. South of the small lakes, it becomes divided into many minor ridges 
and in this form it passes into Indiana. The Eecent beach begins on the University 
grounds in Evanston and keeps near the lake. From Douglas Park it sends a 
branch down to Englewood, and at South Chicago it divides into many minor ridges. 
Some of the minor ridges lie between the smaller lakes. In this divided state, it 
passes eastward into Indiana along the south shore of the lake. These beaches 
were extensively discussed by Dr. Edmund Andrews many years ago, but the 
disastrous fire of 1871 left no copies of his work in the city. Dr. Andrews found 
that the mass of the Eecent (Lower) beach, was almost exactly equal to the sum 
of the masses of the other two beaches. From this the conclusion was drawn 
that the time of the formation of the Eecent beach has been longer than the time 
of the formation of either of the other beaches. 
Fig. 1 . 
Fig. 1 is a diagram of a cross section of these beaches borrowed from Dr. 
Andrews, in which M, represents Lake Michigan; D, boulder clay; 1, Upper 
beach, B, sub-aqueous bar of the Upper beach; 2, Middle beach; 3, Eecent beach, 
B, a sub-aqueous bar of the Eecent beach; S, old soil found in the Lower beach 
and running under the Middle beach; C, clayey deposit of the same age as the 
Upper beach. 
It is probable that the species of plants now existing in this area, have be- 
come indigenous since about the time of the formation of the Upper beach. We 
