198 PROCEEDINGS OF THE ACADEMY OF [1895. 



DOES THE DELAWARE WATER GAP CONSIST OF TWO 

 RIVER GORGES 1 



BY EMMA WALTER. 



The Delaware River passes through the Kittatinny or Blue 

 Mountaiu by a cleft nearly at right' angles to the axis of that range. 

 The entire length of the cut is a little over two miles, but only to 

 the part where it is narrowest or its walls highest and steepest is the 

 term "Water Gap" locally applied. In the following paper, when 

 the Gap is mentioned the entire two miles is included. 



It is clear this remarkable breach in the mountain has been made 

 by river water, and that it is still being deepened by the Delaware, 

 as is stated in the Reports of the Pennsylvania Geological Survey. 



But a study of the marked features of the Water Gap has con- 

 vinced me the Delaware once flowed through it from the south to- 

 wards the north, or in a direction directly opposite to the present 

 flow of the river; also that this north-flowing river was preglacial 

 and that much the larger part, both of the length and depth of 

 of the Gap, was cut by this old river, the remainder being the work 

 of the present south-flowing river since the Ice Age, the Delaware 

 Water Gap being thus composed of two united river gorges, which 

 have been cut from opposite directions. 



If we examine the work of streams which are now forcing their 

 way through hills or mountains, we will see all do their work upon 

 much the same pattern ; that is, a gorge with a funnel-shaped en- 

 trance opening down stream and contracting to a passage with more 

 or less precipitous sides that suddenly expand into an amphitheatre 

 with very precipitous walls. The curve of this amphitheatre always 

 points up the stream, and over the centre the waters tumble into a 

 pool, the depth of which, at the foot of the fall is often very great, 

 even when the stream is quite shallow in all the rest of its course. 



The upper portion of the Delaware Water Gap is just such a 

 gorge, but its funnel-shaped entrance points up stream and not down, 

 as it should if it was the work of the present river. Its amphitheatre 

 rounds down stream instead of up as it would if it had been cut by 



