Page:The Journal of geology (IA journalofgeology21894univers).pdf/77
- the junction of the Little Flat Rock creek with the Flat Rock creek, the old and the new channels approximately coincide. The old channel has been modified and lowered to about the level of that of the present streams.
- The old channel departs from the recent channel at the point last described, and may be traced a little west of south to Milford P.O. It is about thirty feet above the recent channel of the Flat Rock creek at the point of departure, and has but a slight fall. The Flat Rock creek, in cutting its channel toward the north from the point where it left this ancient river, has carried away its water supply, leaving the abandoned part of the old river a relatively high marshy region known to the early settlers as "Beaver Pond." Recently an open ditch has been cut through it converting it into fertile corn an wheat land.
- From Milford the present Clifty creek flows through the old channel and has modified it, as in the case of the Little Flat Rock creek above mentioned.
If the Flat Rock and the Little Flat Rock creeks existed contemporaneously with the old stream they, as well as Clifty creek, were tributaries to it at the points named as their confluence, and doubtless flowed at the same relative level and had a less rapid fall than now. The evidence collected in regard to the bed of the old stream shows that it ran over the Niagara limestone in the upper part of its course with the exception of the region between the Flat Rock creek and Clifty creek (Section III.), where it flowed over Pleistocene deposits of considerable depth as shown by well sections. One of these, just below the C. C. C. & St. L. Ry. (see map), penetrated sand, clay, and bowlder clay to a depth of 135 feet without reaching rock. Another, a short distance below, is seventy-five feet deep in similar deposits without reaching their bottom.
The facts so far observed do not show precisely when the stream originated nor exactly how long it continued before its waters were diverted into their present courses. It seems probable, however, that it originated immediately after the retreat of the ice from the region, and was a part of the first definite system