MORAINIC SYSTEMS AT HEADS OP LAKE MICHIGAN AND SAGINAW BASINS. 181 



the city. It is not improbable that the rock surface is as low beneath the gravel plain as in the 

 valley, and if so the drift may be about 300 feet thick in the highest part of the gravel plain. 



INTERMORAINIC GRAVEL PLAIN. 



The gravel plain between the two ridges of the Kalamazoo morainic system has a general 

 width of about a mile, but in places it is nearly or quite pinched out by protrusions of the inner 

 toward the outer ridge. Its continuity is further broken by basins which fill it almost from 

 side to side. It furnishes, however, a continuous line of glacial drainage from the head of the 

 east branch of Dowagiac Kiver in southeastern Van Buren County, Mich., to the St. Joseph 

 Valley at South Bend, Ind. It descends gradually from about 930 feet near the head of the 

 Dowagiac to 850 feet at Lagrange, Mich, (where the stream leaves the gravel plain to run north- 

 west into the west branch), to about 775 feet east of Niles, and to 750 feet or less to the St. Joseph 

 plain near South Bend. 



Some difficulty is found in interpreting the direction of discharge hi the part of the gravel 

 plain north of the head of the east branch of Dowagiac River. This northern portion nowhere 

 appears to exceed 950 feet, and in the vicinity of Kalamazoo River is only about 930 feet, or 

 as low as at the head of Dowagiac River. One section of the gravel plain about 14 miles in 

 length, which is cut about midway by the main line of the Michigan Central Railroad, may have 

 found discharge eastward through the eastern ridge at a gap occupied by Crooked Lake and 

 thence northeastward along the valley cut in the gravel plain. This section is shut off from 

 East Dowagiac River on the southwest by a protrusion from the western ridge east of Lawton, 

 and is bordered on the north by a prominent ridge that runs eastward toward Brownells station. 

 Between this last ridge and another projection of the western moraine, which extends southeast- 

 ward from Alamo to Brownells, is a small gravel plain occupying about 2 square mUes whose 

 altitude is 950 feet and whose line of discharge was probably through narrow sloughs that cross 

 the eastern ridge near Brownells. Near Cooper a gravel plain on the west side of the Kala- 

 mazoo, standing about 930 feet above sea level, probably drained southeastward past Kala- 

 mazoo. The portion north of Kalamazoo River is likely also to have drained southeastward. 



So far as can be ascertained from well records, the gravel plain between the two ridges of 

 the Kalamazoo morainic system is underlain throughout its entire length by very thick deposits 

 of gravel and sand; at least it has so far furnished no evidence of blue till at moderate depths, 

 and it thus contrasts with the outwash apron outside the outer ridge. 



KALAMAZOO VALLEY. 



In traversing this outwash district from near Galesburg to Kalamazoo, the Kalamazoo 

 Valley leads directly across the line of glacial drainage and then turns northward in a direction 

 opposite to that of the glacial drainage. Under ordinary conditions one would expect the 

 modern drainage to turn southward along the line of the glacial drainage, especially if the dis- 

 trict outside the Kalamazoo morainic system was graded up to a southward slope. The size of 

 this portion of the Kalamazoo Valley is also remarkable, being 1J to 2 miles wide and about 100 

 feet deep throughout its course across the outwash district. The valley also is characterized 

 by irregularities not easily referred to drainage erosion, there being recesses in the bluffs and 

 ridgings along the slopes that seem better explained as the result of glacial action. The course 

 of the valley, its great size, and the irregularities of its bluffs suggest the persistence of a mass 

 of stagnant ice along its course during the deposition of the outwash gravel. The subsequent 

 melting of the ice would leave this belt, traversed by the river, lower than the bordering dis- 

 tricts and would thus determine the course of drainage. Gull Lake, a few miles northeast of 

 Kalamazoo, is in a large basin which is like that postulated for this section of Kalamazoo River 

 but which did not fall within reach of a river. 



A conspicuous feature of the valley is a broad terrace on the east side of the river immediately 

 north of Kalamazoo. It stands about 850 feet above sea level, or a few feet below the level of 

 the gravel plain that extends southward from Kalamazoo River. It seems to have been formed 



