The Orifjin of the Wind Gap.— Wrujht. 121 
(Jlinton shales and then to the Lower Helderberg limestone. 
Aqiianchicola creek, tiowing west, and ('herry creek, flowing 
east, follow along near the border between the limestone and 
the shale. North of the limestone 3'ou find the Oriskany 
sandstone, and then the Corniferoiis limestone, which, how- 
ever, runs out before reaching the Lehigh river. South of the 
mountain you pass from the Medina and Oneida sandstones 
to the Hudson River shales and Utica slates. 
''The summit level [of the Wind gap] at the center point 
of the bottom of the notch has an elevation of 978 ft. A. T. 
The crest of the mountain rises about 500 ft. higher. Meas- 
ured at the crest line of the mountain the width of the gap 
is about three-fourths of a mile. The side slopes are beauti- 
fully rounded and curved downwards and pretty steep, so that 
the tloor of the notch is about one-eighth of a mile wide."* 
The slope to the south of the gap is much steeper than that 
to the north. A little stream rises on the north slope of the 
mountain east of the Wind gap and flows westward to Aquan- 
chicola creek ; but r.o stream runs through the gap. Never- 
theless the general appearance of the notch is such that one 
cannot help believing that at some time a stream ran over 
Blue mountain at this point and cut the gap. Also in exca- 
vating for a railroad through here they found, at a depth of 
twelve feet, waterworn pebbles, which indicate the former 
existence of a stream. f But, as it is quite probable that this 
gap furnished an outlet to the south for the water from the 
melting ice during the later part of the Glacial period, this 
may account for the waterworn i)el)bles. However, there 
seems to be no evidence that either the ice-sheet or changes of 
drainage caused by it had anything to do with the formation 
of the Wind gap. This cut must have been made long ante- 
rior to the Glacial period by some stream that flowed over the 
mountain at this place before the existing topography had 
been assumed, as is evident from the fact that there is no 
trace of the old channel north or south of the ga]), and that 
the land slopes quite rapidly down on both sides from it. The 
present paper relates to tlie question. What has become of 
this riverV 
*Penn. Geol. Survey. G(i, p. 6.3. 
fPenn. Geol. Survey, G6, p. C^.^. 
