322 PLEISTOCENE OF INDIANA AND MICHIGAN. 



LAKE MAUMEE. 



Lake Maumee had at least three distinct stages and possibly more. Those clearly deter- 

 mined are as follows: 



Highest stage. — As the ice front retreated eastward from the moraine at Fort Wayne, Ind., it 

 uncovered what is now the upper Maumee Valley, but continued to occupy the present lower part 

 of that valley and therefore to obstruct its normal northeastward drainage. Consequently, 

 Lake Maumee came into existence between the moraine and the ice front. As the ice retreated 

 the lake widened eastward and long arms of water extended eastward into Ohio and northeast- 

 ward into Michigan between the shrinking ice lobe and the land. 



How far the ice retreated is not certain. The next strong moraine in the Maumee Valley is 

 at Defiance, Ohio, but in view of the periodicity and the wide space covered by the readvances, it 

 may be regarded as certain that the retreating ice front did not stop at Defiance but receded to a 

 point probably not less than 25 or 30 miles east of that place and there halted for a considerable 

 time before readvancing. There were also minor oscillations during both of these movements. 



The waters of the lake rose until they found an outlet westward through the present site of 

 Fort Wayne and thence southwestward to Wabash River at Huntington and ultimately to 

 Ohio and Mississippi rivers and the Gulf of Mexico. The time of the opening of this outlet is not 

 certain. Possibly the lake stood at its highest level and discharged at Fort Wayne during the 

 climax of its retreat, although this is doubtful. But during its readvance to Defiance and its 

 pause at the Defiance moraine it certainly overflowed at Fort Wayne. The first stage ended only 

 when the Fort Wayne outlet was finally abandoned. 



Lowest stage. — When the ice front retreated from the Defiance moraine it fell back a long 

 step to the eastward and opened a lower outlet somewhere near Imlay, in Lapeer County, Mich. 

 Below the highest or first beach of Lake Maumee there are two others which evidently belong to 

 this lake. One, the middle beach of Lake Maumee, is 15 to 25 feet below the first beach 

 and is a normal wave-made shore line of moderate strength. The other or lowest beach, 

 which is about 20 feet below the middle beach, is faint and fragmentary and has been greatly 

 modified by later submergence. These two lower beaches have a curious relation; the lowest 

 beach was made next after the highest and then the level of the lake was raised and the middle 

 beach was made at a higher level. The storm waves which made the middle beach swept 

 over the gravelly ridges of the earlier one below, which lay in 20 feet of water, and almost 

 destroyed them. Hence, when the lowest beach was being made the lake was in the second 

 stage. The location of the outlet for this stage is not known with certainty; it may have 

 passed northward a few miles east of Imlay and thence westward across Tuscola County, but if 

 so it was overridden and obliterated by a readvance of the ice. In its horizontal part the lowest 

 beach is 760 feet above sea level. 



Middle stage. — When the ice front readvanced, it closed the outlet for the lowest stage and 

 moved westward to a position close along the east side of the great Imlay outlet channel, which 

 passes northward just east of Imlay. This channel shows evidence of having been crowded 

 westward by the ice as it was building the moraine along its east side. At this stage Lake Mau- 

 mee was barely too low to overflow at Fort Wayne. 



When the ice retreated from this last position, it opened a temporary outlet across Tuscola 

 County, but did not open a permanent new outlet until it had retreated many miles to the 

 north toward the northern part of the "thumb." The opening then made, however, allowed 

 the lake waters to fall suddenly to a much lower level. 



In the middle or latest stage Lake Maumee reached its greatest extent, stretching from Fort 

 Wayne, Ind., northward to a point several miles north of Imlay, Mich., and eastward nearly to 

 Girard, Pa. The front of the contemporary ice lobes probably extended from the vicinity of 

 Detroit into Lake Erie, 40 or 50 miles east of Toledo. At its front the ice was therefore standing 

 in water 150 to 200 feet deep. 



