BURIED VALLEY OF SUSQUEHANNA RIVER 563 
presented a condition very favorable to the development of a 
feature of this kind. A stream flowing out of the mountains to the 
north and having sufficiently low outlet to afford declivity could 
naturally excavate a deep channel along this valley near the axis of 
the syncline. It could not, however, excavate basins with their 
bottom materially below its mean grade, that is, there would be no 
very deep holes in its course. However, when the glacier advanced 
southward it crossed this valley diagonally and probably picked up 
a large amount of loose material from its bottom. At this stage and 
later, subglacial streams also would have had the tendency to deepen 
basins in the valley bottom. It is believed then that the basins and 
troughs in the bottom of the old valley were excavated by glacial 
action largely by the removal of soft and disintegrated material by 
the ice as it moved across the valley. Later, when the river resumed 
its flow, large amounts of sand and gravel were carried down the 
valley and by this means the deeper parts of the old valley were 
filled to the present level. Apparently there was diminished 
declivity in this later stage or the river would have re-established 
the earlier gradient. The filling has continued for a long time and 
it is now in progress, for deposition is in excess of erosion and at 
times of great freshets a widespread sheet of mud is laid on the lower 
lands bordering the river. 
The buried valleys of Mill Creek and Newport Creek with their 
deep holes are to be explained in the same manner as that of the 
river. Mill Creek has had an interesting history, for not so very 
long ago, geologically, it emptied into the river on the southwestern 
part of Wilkes-Barré. This is shown by the continuity of its old 
valley under the central part of the city. Later it was tapped off 
by a small stream cutting back through the ridge east of Prospect 
Colliery and it now flows to the river through a short, rocky gorge. 
