Little Rocky Glen is one of the best examples of
geological forces in action within the the watershed. It is
the highest outcrop in the area, and is an area of significant
Holocene (post-glacial) erosion. This outcrop was cut and
eroded since the glacier left this area about 18,000 years ago.
If you look carefully, you may find evidence of
ripple marks and an incipient pothole. Frequently when a sizable
stream flows over a bedrock ledge, potholes are formed by vortices in the water.When the vortex comes upon an imperfection in the stream bottom,
particles collect there which act as grindstones.Several potholes may coalesce forming a slot canyon.
At this site, the stream is cutting down through a moderately resistant
sandstone. If the bedrock here were shale, the canyon would be much deeper as the
shale would be more easily eroded.Little
Rocky Glen is reminiscent of
The
Seven Tubs, a natural area in Luzerne County which is also eroding through a
tough sandstone, but has more erosive tools in the form of water flow and stream
gradient.
