338 PLEISTOCENE OF INDIANA AND MICHIGAN. 



the shore, and then by heavy gales, usually from a westerly direction, is driven with great force 

 upon the easterly or southeasterly shores. On ordinary shores with bluff banks and steep descent 

 the ice simply batters the shore and breaks up, producing no unusual result. But if the offshore 

 slope be very gentle and the ground back from the water's edge low and flat, the ice meets rela- 

 tively slight resistance and by sliding on the bottom rides up out of the water onto the land, 

 sometimes pushing scores of feet beyond the water's edge. 



In sliding up the gentle incline the ice is cracked at intervals, but the pieces are usually not 

 disjointed nor separated and the whole mass is pushed forward with tremendous force, carrying 

 everything movable before it and gathering up a ridge of mixed materials to be finally left in the 

 form of a rampart. 



RAMPARTS ON LAKE MATJMEE. 

 INTERPRETATION. 



So far as the writer is aware, the occurrence of this process on a large scale in the past has 

 not been clearly inferred from anything observed hitherto, but in the district under considera- 

 tion a remarkable group of ridges associated chiefly with the highest beach of Lake Maumee shows 

 peculiarities of form, composition, and general relations that are inexplicable, except on the 

 supposition that they are ice ramparts. On this supposition all of their peculiarities are clearly 

 explained. These ridges occur on the south shore of Lake Maumee, chiefly between Delphos 

 and Findlay (see PI. XV), where the trend of the old shore is southwest and northeast. 

 Their principal development is between Gomer, 8 miles east of Delphos, and Benton Ridge, 22 

 miles northeast of Gomer. 



The ice ramparts of Lake Maumee are in many respects very different from the forms com- 

 mon on the shores of the small lakes. In the first place the whole phenomenon is on a scale many 

 times greater than that of the small lakes. Instead of being composed mainly of bowlders, 

 pebbles, and rubbish, those of Lake Maumee are composed chiefly of gravel and clay, the clay in 

 many places making more than half the mass. 



The early students of this region appear to have paid no special attention to these ridges 

 but to have regarded them as ordinary beach ridges. Although their situation and relations to 

 the shore of Lake Maumee and to the beach ridges mark them as closely related forms, their 

 clayey composition excludes them from the category of true wave-made deposits. They show 

 also peculiarities of plan and general relations that are abnormal for beach ridges formed under 

 the very simple conditions of this district, where the country for several miles north of the 

 beaches is extremely flat and even, its general slope being north-northwest 5 to 10 feet to the 

 mile. The extreme shallowness of the lake waters for several miles offshore was probably not 

 equaled elsewhere in the lake region. More particularly was this true when the lake was first 

 formed and the waves had not yet had time to modify the lake floor. 



Normal beach formation on such a shore generally results in the formation of beach ridges 

 on straight or very gently curving fines following the course of a contour. It does not tend to 

 the formation of crooks nor sharp bends, nor, with only small streams and low gradients, to the 

 formation of notable delta irregularities. As the present stream beds of the region are narrow 

 and only slightly depressed in the flat plain and were less depressed in glacial times than now, there 

 appears to have been no cause in the topographic environment for exceptional or peculiar beach 

 forms. 



DISTRIBUTION AND CHARACTER. 



Within 3 miles of Columbus Grove, four branch ridges, 3 or 4 miles long, appear to split off 

 from the south side of the middle beach of Lake Maumee and run southwest a little more south 

 than the main ridge. These branch or spur ridges are more like true beach ridges than the frag- 

 ments east of Pandora, because they have suffered less modification. They appear to be con- 

 nected with the middle beach but are mostly higher, especially toward their southwest ends, 

 where they rise to the level of the highest beach. 



