Catskill stratification question

[Orphic Seth]

So today my work brought me to the Hudson River Valley, where I enjoyed beautiful views of the Catskills. Now, I have never hiked in the Catskills, but have oft enjoyed them from afar (like from the Mass/NY pike/thruway). One thing I noticed today were distinct horizonta stratified lines banding the mountains. Rock or vegetation, I know not which one, I'm leaning towards vegetation patterns. It reminded me about those big rocky parks out west where you can see the layers of dirt and rock from the past millenia.

Do these distinct lines that mark the Catskills have anything to do with the underlying rock layers affecting the shadows/vegetation, what have you, or is there something else at work here?

Those in the know, please enlighten me. If, for some reason, I haven't described it enough, let me know.

 

[Jay H]

The entire Hudson valley (including the Berkshires and the Taconics) was once a huge plateau... The hudson river has carved a large rift between them. If you look at the map, the berkshires are roughly the same latitude of the Blackhead Range in the northern Catskill high peaks region. The hudson river did a nice job of carving them out. Glaciers and river beds have also carved a bit out of the catskills as if you have the NYNJTC catskill maps, it shows the Catskill's Divide. where the water flows either to the Hudson river or to the Delaware River. These rivers have also made their mark on the geology of the catskills.. panther mtn was the site of an ancient asteroid hit too, as you can see the Esopus go around what is now Panther mtn.

Riverbeds are commonly looked at and can be seen as you drive through many of the roads that go south/north through the catskills... Route 42, 212, 214, 47.

The fact that it was an eroded plateau also shows why any catskill hiker will come across many rock ledges around 3000ft.. Almost never fails!

Vegetation probably falls in line with the soil quality the old river beds, elevation temps, etc.

Jay

 

[Papa Bear]

There's a very good Geologic Map in the front of the NY Walk Book, published by the NYNJTC. It maps the Catskill Plateau as sedimentary from the Devonian period. The best place to see this is probably the delaware valley which cuts right through this plateau.

Certain areas are older, such as the Taconics (Cambrian) and the NJ Highlands (Pre-Cambrian/Metamorphic). If you take a boat up the Hudson you can readily see how the highlands are much harder rock: between West Point-Breakneck Ridge and Bear Mountain-Jones Nose, the river really had a tough job making it's way through this section. And it makes for dramatich hiking.

Nice map. Nice book.

 

[Warren]

The Catskills Forest: A History will tell you loads of info on this topic.

There is distinct stratification in the Catskills, viewable on almost any trail. Stratification of vegetation is a matter of altitude as much as soil if not more so. You can usually guess altitude by vegetation changes.

 

[rondak46]

Level stratification..

Notably (to me anyway) is the level stratification in the Catskills. The layers are level and flat. This indicates that these layers were unaffected by uplift, subduction and other tectonic activities. Snow highlights the layers during the colder months and it can be seen very clearly on the blackhead range as you head south. The layers that are exposed in Thatcher Park show an abundance of marine fossils.

When I was growing up we had a set of World Book encyclopedias. I thought these were the greatest books until, when I was around 20 and had become a hiker, I was habitually flipping through them one day. I came upon the entry for the Catskill Mountains. The first sentence said "The Catskills are really not mountains, but an eroded plateau". I was insensed and packed up my beloved books and donated them to some charity. The author had apparently not climbed them to get a View From The Top.

Mike

 

[imarchant]

I believe there are some of both. As Jay stated there is the rock ledges at about 3,000 ft. i.e. the escarpment and the ledge around Overlook Mountain. These make a clear stratification line viewed from areas between the Kingston-Rhinecliff and Catskill Bridges.

Then there is also a change from deciduous to conifer forest. This seems to occure at about 3,300 to 3,500 ft. The book Warren refers to is written by Michael Kudish. It has many details about the forests and history of the catskills. I hope Mark Schaefer replies, he is very knowledgeable about this subject (I think he has memorized that book).

 

[moonrock]

catskill delta

Here is a nice pictoral summary and explanation.

http://www.priweb.org/ed/TFGuide/NE/geo_history/history_files2/history_pdfs/ne_geohistory4.pdf

Other sites can be found by googling
"catskill delta"

Basically, the catskill sequence was formed by sediments eroding west from mountains forming in central New England (east of the Taconics, and later)
into a shallow inland sea. But because of cyclical variations in the earth's orbit and tilt (simplified), world sea level, and water depth over the delta, varied over time, resulting in cyclical deposits of shallow and deep water sediment.
Also, multiple flood-event deposits in the delta graded from sand, up into silt and clay, forming distinctive beds where sandstone sticks out, and shale weathers/erodes away

BTW: the Gunks fit into this as the most proximal (coarse and presumably uppermost) deposits from those old mountains. I'm sure there are plenty of
Cornell or RPI alums who will gladly flame me over the details.

Can it get more interesting ? A primordial (long buried) meteor/asteroid crater was identified in the general area as well. See Roadside Geology of NY for more details.

Moonrock

 

[moonrock]

Oops

Gunks pre-date the catskill sequence - My Bad !

 

[Ned Kipperson]

The Catskills are the remains of a delta formed from an old sea (glacial Lake Albany, I think), part of the Alleghany plateau which extends from NY's Southern tier down through PA and WV. The reason the tops are so prominent and high in elevation compared to the rest of the plateau (like near Binghampton) is the hard conglomerate caps. This can easily be seen on Slide mountain, the top has less stratification and has course gravelly deposits. Geologic dissertations can make the brain hurt, so this is the layman's guide.

 

[moonrock]

Uh Uh!

Glacial history was the icing on the cake (or the sculpting thereof) in the NE US.
Lake Albany deposits are clays and silts locally deposited within the last 10-12 thousand years, as continental glaciers melted away, and the earth's crust sequentially rebounded around 1000 vertical ft from an approximately 3000 ft (local) ice load. This process progressed up the Hudson Valley, producing warped (or tilted) beach deposits still visible along the walls of the Valley (beaches are esp visible north of I-90, east of Albany near Exit 9). The fun part is that a trained eye can "read" surficial geology from topo maps, just from the patterns/texture of the contours !
My Grad Mentor, Dr. Robert Lafleur, mapped the Albany/Troy area.

But the Catskill Delta was a different time scale, 30,000 times as old.

 

[Mark Schaefer]

The Catskill rocks (Catskill Delta, 320-417 million years ago) and those that lie beneath (Queenston Delta, 500-430 million years ago) are sedimentary, formed below sea level, and formed while the area was in the tropics.

The strata of the Catskills escaped folding by being just sufficiently distant from the successive continental collisions that formed the Taconics, the Arcadians, and today's Appalachians. Schunemunk Mountain (a small isolated fragment of the Catskill Delta) was folded by the most recent collision. The New York Walk Book's chapter on Schunemunk is good reference. The pressure of this collision which concluded about 290 million years ago, caused the Catskills to rise 7000'. The Catskills were still in the tropics at this time. From that point the Catskills began to erode, and were only later affected by glaciation as the continent drifted north.

This USGS webpage has some good diagrams of the continental collisions and the delta formation, as well as some suggested roadside field trips.

The horizontal Catskill strata consists of alternating layers of sandstone (cemented sands), and harder shales (clay, mud, silt). These are the horizontal lines you see in exposed escarpments.

Others have mentioned the band of conifers at the higher summits. There are also randomly located pine and spruce reforestation areas. These are often planted on former pastures, occasionally have straight borders, sometimes bounded by straight stone walls.