GLACIAL LAKE MAUMEE. 335 



It seems quite certain that the highest beach is not represented in this interval by a strong 

 separate shore line, like that west of the Defiance moraine, or it could hardly have been over- 

 looked. That it was not formed east of the Defiance moraine seems improbable, because east 

 of this same moraine in Michigan it is strongly developed in independent form and all three 

 beaches extend up to the vicinity of the Imlay outlet. If it was made inside the Defiance 

 moraine in Michigan, it should have been formed inside the moraine in Ohio. It is therefore 

 regarded as possible that the highest beach in this interval stood at about the same level as 

 the middle, and that fragments of the highest may he in discordant relations behind the 

 middle. More field studies bearing on this question are needed. 



If the middle beach is, in fact, as high or higher than the first or highest beach on the south 

 side of the basin east of the Defiance moraine but not west of it, the cause of such a relation is 

 somewhat difficult to find. At present no satisfactory explanation seems available — nothing 

 better than an arbitrary assumption of slight local subsidence of the land after the formation 

 of the highest beach and before the formation of the middle one. If the highest beach were 

 confined to the basin west of the Defiance moraine, both north and south of Maumee River, 

 the relations would be simple enough, but such does not appear to be the case. Somewhat 

 similar conditions occur in connection with the beaches of Lake Arkona but nowhere else, so 

 far as is known. 



CHARACTERISTICS OF LOWEST BEACH AND RELATED DELTAS. 



Mr. Leverett points out ' that the lowest beach has a " washed-down ' ' appearance, as if it had 

 been submerged and modified. Later investigations in connection with Lake Arkona (p. 362) 

 have fully established the fact that beaches have been submerged and modified and in places 

 have been almost totally destroyed. Certain characteristics qualities very clearly distinguish 

 such modified beaches from others that have not been submerged, and these same characters 

 are distinctly shown by the lowest beach of Lake Maumee. Even where composed of gravel, it 

 is more fragmentary than other gravelly beaches, and at most though not at all points it has a 

 lower relief than normal gravel beach ridges. In some intervals the beach deposit appears to 

 be absent entirely, and in others it has a "washed-down" appearance and its ridges and gravelly 

 deltas contain more clay and have a stiffer soil than normal beaches and deltas. 



A characteristic feature of the Arkona shore lines is the remarkable way in which the deltas 

 connected with them protrude beyond the general line of the shore. The Arkona delta of 

 Huron River carries the beaches out into the lake 2 or 3 miles beyond the general lake border. 

 In less degree the gravelly deltas associated with the lowest beach of Lake Maumee show the 

 same habit of protrusion beyond the general line of the shore. This relation appears to be 

 accounted for mainly by the fact that these deltas were built by streams entering the lake in 

 beds that had not been previously trenched to or below the lake level of that stage. Neither at 

 their mouths nor in their lower courses did these streams have any preexisting vaUey or bed in 

 which the coarser sediments could lodge. Hence, all of their sediments were carried beyond 

 the original contour of the shore and were deposited in a mass that carried that contour out into 

 the lake. It was quite different with Lake Whittlesey, for that lake was superposed on a 

 surface previously trenched by streams, and the trenches made by those streams absorbed 

 nearly all the materials commonly built into deltas, so that Lake Whittlesey had no protruding 

 deltas, but only estuarine or valley-set deltas. 



Rouge River at Plymouth made a rather prominent delta in connection with the lowest 

 beach, and the beach ridge associated with it is greatly strengthened. At Rochester the delta 

 is not quite so prominent but has the common characteristics. At Ypsilanti the delta is very 

 prominent and extends about 2 miles beyond the general shore line. East of Ypsilanti it 

 contains one or two strongly marked distributary channels. The deltas south of Saline and 

 Tecumseh are not so prominent, but they show the same modification by submergence. 



These characteristics of the lowest beach and of the deltas associated with it seem to leave 

 no doubt that this beach, although located farther down the slope, was made before the middle 

 beach, and that after it was made the lake was raised to the level of the middle beach. While the 

 latter beach was being made, the lowest beach was submerged and was undergoing modification. 



1 Ann Arbor folio (No. 155), Geol. Atlas U. S., U. S. Geol. Survey, 1908, p. 7. 



