Tuesday, May 29, 2012

Day 7 - North Lake

On Thursday, May 24, my Geology of the Hudson Valley field course visited North-South Lake - a DEC campground and day-use area.  The weather wasn't too nice, it rained on and off the whole time and there were no views from the Escarpment Trail - just a fog bank.  This photo gives you a flavor of the day.

The area around North Lake has a long and interesting history.  There were once luxury resort hotels here, like the Catskill Mountain House that were haunts of the 19th century rich and famous and are now only a memory.

The Hudson River School of artists also favored the scenic beauty of the area.

Kindred Spirits by Asher Durand (1839) on left and
Kaaterskill Falls by Thomas Cole (1826) on right
(click on images to enlarge)

This area is interesting geologically as well, being in the sedimentary rocks of the Catskill Mountains.  The Catskills are not a true mountain belt - they're composed of undeformed sedimentary rocks - but rather a dissected plateau.

These sedimentary rocks - shales, sandstones, and conglomerates - represent sediments eroded off the ancient Acadian Mountains to the east.  These Himalayan-scale mountains formed when a small microcontinent (Avalonia) collided with what's now the Eastern U.S.  Mountain streams, meandering rivers, floodplains, beaches, and shallow seas of the Catskill Delta system are depositional environments represented by these sedimentary rocks.

To the right is a simple illustration of what the area looked like in the Mid- to Late-Devonian Period.  We were also in a sub-tropical climate zone at the time (about 30 degrees south latitude!).  The best modern analogue is the Ganges Delta of India where streams draining the Himalaya enter the Bay of Bengal.

After a hike along the escarpment trail (where we examined cross-bedded sandstones, puddingstone conglomerates, joint sets, and glacial erratics and striations) to a cloud-shrouded Sunset Rock (famous among the Hudson River School Painters), we chilled for a bit at the top of Kaaterskill Falls (highest in NY State) where cross-bedded sandstones sit atop more easily-eroded redbed shales.

Since we were able to get back to Campus relatively early (due to the cloudy, rainy weather at North Lake), we decided on a quick visit to visit a local cave (Pompey's Cave).  Pompey's Cave is an excellent local example of a karst area with a stream/swamp that seeps down through solution joints into a cave system.  What's left behind is a dry stream bed with a couple of skylights into a cave tunnel about 12 feet under the stream bed in which a stream now flows underground.  The stream exits through a series of springs further downstream.

The dry streambed above Pompey's Cave

The cave is easy to get into with a ladder but the stream in the cave was too high (with rain all week) to safely explore.  We also inadvertently disturbed some people down there (a student knew a couple of them and the person leading the ceremony is a well-known local Native American) who were having a ceremony (burning sage and drumming).  I felt bad about barging in on them like that but we didn't stay long!

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