SURFACE GEOLOGY. A9 
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 o 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 Hrie. 
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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