SURFACE GEOLOGY. 49 



the rolled and rounded condition of the gravel and bowlders which com- 

 pose this great bed of valley Drift plainly records the action of a steady 

 flowing, though powerful stream. 



A more recent water-gap, yet very ancient, apparently similar in 

 character to those described above, is that which connects the valley of 

 the Maumee with that of the Wabash. Of this a detailed description is 

 given by Mr. G. K. Gilbert in his report on the " Surface Geology of the 

 Maumee Valley." As this is so minute and graphic, I quote largely 

 from- it, for the purpose of bringing the facts he cites into connection 

 with those observed by myself. Speaking of the old lake beaches, he 

 says: 



"The upper beach (having an altitude of 220 feet above the Lake) consists in this 

 region of a single, bold ridge of sand, pursuing a remarkably straight course, in a 

 north-east and south-west direction, through portions of Defiance, "Williams, and Ful- 

 ton counties. When Lake Erie stood at this level it was merged in the north with 

 Lake Huron. Its south-west shore crossed Putnam, Allen, and Van Wert counties, 

 and stretched north-west in Indiana nearly to Fort Wayne. The north-western shore 

 line, leaving Ohio on the south line of Defiance county, is likewise continued into In- 

 diana, and the two converge at New Haven, six miles east of Fort Wayne. They do 

 not, however, unite, but, instead, become parallel, and are continued as the sides of 

 a broad water-course, through which the great lake basin then discharged its sur- 

 plus waters south-westward into the valley of the Wabash river, and thence to the 

 Mississippi. At New Haven this channel is not less than a mile and a half broad, and 

 has an average depth of twenty feet, with sides and bottom of Drift. For twenty- 

 five miles this character continues, and there is no notable fall. Three miles above 

 Huntington, Indiana, however, the Drift bottom is replaced by a floor of Niagara 

 limestone, and the descent westward becomes comparatively quite rapid. At Hunt- 

 ington the valley is walled, on one side at least, by rock in situ. In the eastern por- 

 tion of this ancient river bed the Maumee and its branches have cut channels fifteen 

 to twenty-five feet deep, without meeting the underlying limestone. Most of the in- 

 terval from Fort Wayne to Huntington is occupied by a marsh, over which meanders 

 the Little river, an insignificant stream, whose only claim to the title of river seems 

 to lie in the magnitude of the deserted channel of which it is sole occupant. At 

 Huntington the Wabash emerges from a narrow cleft of its own carving, and takes 

 possession of the broad trough to" which it was once but a humble tributary. The 

 limestone above Huntington is the rocky rim, or dam, which determined the altitude 

 of the overflow at this point, and is 170 feet above the present level of Lake Erie. 

 Above it the stream must have resembled the Detroit, bearing a smooth surface, but 

 with enough current to excavate its soft bottom somewhat deeply where the marsh 

 and prairie of the Little river are now spread ; below, it was more comparable to the 

 Niagara at Buffalo, where it rushes over the outcrop of the Corniferous limestone. 

 At Fort Wayne the St. Joseph's and St. Mary's contributed their waters. Their 

 mouths were fifty feet higher than now, and the flood-plains of gravel and sand 

 which they then formed now flank their valleys as terraces, and can be traced for 



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