GLACIAL LAKE MAUMEE. 337 



The middle beach enters the Delphos quadrangle at an altitude of 770 to 777 feet and holds 

 it as far as Pandora. From Pandora to Benton Ridge it rises to over 790 feet and is associated 

 with some exceptional features. (See p. 340.) It is in many places not more than 10 feet and in 

 most places not more than 15 feet below the highest beach. In a few places the interval is 

 greater than 15 feet. These variations of vertical interval are due chiefly to variations in devel- 

 opment; where the highest beach is weak and the middle one strong the interval is less than 

 the mean, and where the highest beach is strong and the middle one weak the interval is greater 

 than the mean. 



Eastward from the Defiance moraine the middle beach appears to mark the limits of Lake 

 Maumee. It rises from about 770 feet near Leipsic to 780 or 782 feet near Berea and in Cleve- 

 land. From Cleveland northeastward to Mentor, a distance of a httle over 20 miles, it rises to 

 791 feet. Eastward from Mentor it runs at nearly the same level about to Ashtabula, where all 

 the beaches begin to rise. At the Ohio-Pennsylvania State line the beaches are all 8 or 10 feet 

 higher than at Ashtabula, and from the State line they all rise more rapidly northeastward. 



The lowest beach is weak and fragmentary but is fairly well defined in the Delphos, 

 Columbus Grove, Bluffton, Ottawa, and Deshler quadrangles in Ohio. Its altitude is a httle 

 above 750 feet. Several points show 752 feet and others as much as 757 or 758 feet. In 

 Michigan this beach is generally at or slightly above 760 feet, but in Ohio it averages about 

 755 feet. The lowest beaches near the Fort Wayne outlet are near enough to this level to 

 suggest their probable identity. 



So far as observed in Michigan the lowest beach is everywhere about 20 feet below the 

 middle one. It has not been observed north of Romeo, in Macomb County, where it is a weak 

 feature at about 790 feet, the middle beach being at 810 feet. 



Since the discovery of the lowest beach some uncertainty has arisen as to the identity and 

 northeastward extent of the middle and lowest Maumee beaches, but there has been no oppor- 

 tunity to reexamine the ground. It seems likely, as stated above, that the delta-like deposits 

 at Fairview, Pa., and the faint beach and delta deposit at Girard, Pa., belong to the lowest beach. 

 Their height above the Whittlesey beach indicates this, and if such is their relation it may be 

 that somewhere west of Girard the middle beach becomes too weak to be traced. However, if 

 the lowest beach was made at a back-step halt of the ice front and the middle beach after 

 readvance and a raising of the lake level, as supposed, then some part of the lowest beach was 

 overridden and obliterated by that readvance. The middle beach would then be faint at its 

 end and could not, in all probability, be traced so far to the northeast. The deposit at Girard, 

 Pa., has an altitude of 770 to 775 feet and is 25 or 30 feet above the Whittlesey beach. 



A careful comparison of altitudes seems to show all the beaches in the Oberlin quadrangle 

 to be a httle low, possibly because they are protected against the dominant western winds by 

 the high ground in the Vermilion quadrangle to the west. The fact, however, that all beaches 

 are affected alike, although all are not equally protected, renders this explanation somewhat 

 unsatisfactory. 



ICE RAMP ARTS. 



RAMPARTS ON MODERN LAKES. 



In Indiana, Michigan, Iowa, Wisconsin, Minnesota, and probably elsewhere there occur what 

 are known as "walled" lakes 1 — lakes bordered on one or two sides by a narrow ridge or wall of 

 bowlders a few yards back of the shore. Such ridges, called "ice ramparts," are commonly 

 2 to 5 feet high and on some lakes run for long distances. Modern ramparts invariably rest 

 on flat ground and face lakeward over a flat shore and a shallow, smooth lake bottom from a 

 few rods to several hundred feet wide. 



Ice ramparts are the product of wind and floating ice, the ordinary ice coating of the winter 

 season. Toward spring the ice covering the lake thaws around the edge, becomes loosened from 



1 One of the best accounts of these lakes and of the formation of rampart ridges is by E. R. Buckley (Ice ramparts: Trans. Wisconsin Acad. 

 Sci., vol: 13, 1901, pp. 141-162). Dr. C. A. White also discussed walled lakes in his official report as State geologist of Iowa, published in 1870. 



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