160 J. L. Rich — Physiography and Glacial Geology 



miles northeast of Gilboa village. It is nearly half a mile in 

 length and stands about 100 feet high at the front (figs. 10 and 

 11). Along most of the front typical landslide topography 

 has developed, but in one part it is absent and there the delta 

 front is beautifully wave-cut at a level some 30 feet below the 

 top, indicating a short stand of the lake waters at the lower 

 level. 



This delta, also, seems much too large for the small stream, 

 only 3J miles long, in whose valley it occurs. The explanation 

 of its abnormal size is doubtless that during at least a part 

 of the history of Grand Gorge Lake a good-sized glacier 

 tongue pushed through the pass round the end of the Cats- 

 kill Escarpment at Broom Center, discharging its debris-laden 



Fig. 12. 



Fig. 12. The delta north of Conesville. Cattle grazing on top of delta 

 serve as scale. From a photograph. 



waters down the Platter Kill Valley into the lake. Such an 

 interpretation is strongly confirmed by the topographic map 

 which shows what appears to be an extensive series of morainic 

 loops in the upper part of the valley. This interpretation, if 

 correct, will be of assistance in the final correlation of the posi- 

 tions of the ice front during the life of Grand Gorge Lake. 



Deltas on Manor Kill. — On a small branch of Manor Kill, 

 one mile north of Conesville, is a large, well-defined delta 

 at an elevation between 1600 and 1620 feet (fig. 12). This 

 also was probably augmented by the outwash from glacial 

 tongues pushing over the divide from the northeast. 



At the village of Manorkill a pronounced flat-topped bench 

 at a little over 1600 feet is clearly brought out on the contour 



