Geology of Saugerties

Looking down Krout Road towards the bottom of Glacial Lake Albany

Looking down Krout Road towards the bottom of Glacial Lake Albany

Saugerties is a town divided into two halves by one mountain. That’s Mt. Marion, and it runs, north to south, right down the middle of the town. East of Mt. Marion is the most densely populated part of town. This part of Saugerties once lay at the bottom of a great ice age lake: Glacial Lake Albany. West of the mountain, Saugerties shares a lot of the same ice age history as Woodstock. The whole sweeping lowland, there, was once a land across which a great glacier advanced. That was the ice of something called the Wagon Wheel Advance. Those were the very glaciers that continued on into Woodstock and created much of the scenic landscape now owned or managed by the Woodstock Land Conservancy.

That advance of the ice came almost at the end of the Ice Age. That was about 15,000 years ago when there was one final and substantial cooling of the climate. During that episode, ice slid south, past the west side of Mt. Marion, and it did not stop until reaching Bearsville. We have, in earlier columns in Woodstock Times, described what features were produced in Woodstock at that time. The most prominent ones were the several drumlins that are found in and around Zena. Drumlins are streamlined hills that were sculpted by the advancing ice. It picked up sands and gravels and shaped them into symmetrical hills. These hills are stretched out northeast to southwest. Their eastern and western flanks are steep and symmetrical. The northern slopes are short and steep; the southern ones are stretched out with gentle slopes.

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Map view of two drumlins (shaded)

Map view of two drumlins (shaded)

We found three of these in Zena. There are four more in western Saugerties. From West Saugerties take County Rtes. 33, 35, and 36 until you take a right fork onto Buffalo Rd. After a bit, that road will take you up the steep western slope of the Buffalo Rd. drumlin. Then it will take you down the equally steep eastern slope. Don’t do any of this before taking a good look at our illustration. It shows this drumlin as an absolutely perfect example of such a feature. See its symmetry, and see its several slopes and stretched out appearance. It’s oriented south, 20 degrees west; that’s the same pathway the glacier took. It’s not commonly the case that you can drive up and over a drumlin, but Buffalo Rd. does the trick very nicely. We found another drumlin, just to the southwest, and two more south of Centerville, near Rte. 212.

 

After visiting those drumlins we drove Rte. 212 east until we reached downtown Saugerties. Stretching off to the north and to the south is a region sometimes called “Flatbush.” It lies, most of it, within a mile of the Hudson River. As its name suggests, a lot of Flatbush is flat-lying land. Much of it, however, is actually a fairly bumpy landscape. Head north on Rte. 9W and you will see. From downtown Saugerties, north a mile or so, you will find yourself driving on an irregular landscape. Here and there, you will see outcroppings along the road. They show a mixture of dark gray sandstones and black shale. This is the Normanskill Formation and those rocks are about 450 million years old.

But if you turn left on Krout Rd., you will drop down onto a very different form of landscape. Down there is a relatively flat-lying terrain which has been devoted to agricultural practices. If, like us, you bring along a shovel you can sink it into soft masses of silt and clay. These are the deposits of Glacial Lake Albany and they are what make Flatbush a distinctive part of Saugerties.

But we paused at the top of Krout Rd. Suddenly, it was 15,000 years ago. Behind us, to the east, Glacial Lake Albany stretched out almost three miles. Our perch on Krout Road lay upon large bedrock island in that lake. Ahead of us was a smaller part of the lake; it stretched out a mile to the west. We saw half a dozen smaller islands out there. Suddenly, it was like a movie; the waters of the lake parted and, a full 60 feet below us, the flat, wet, muddy, lake bottom appeared. Then, quickly, all the waters disappeared and we viewed Krout Rd., once again, as it is today.

Back during the latest phases of the Ice Age, much of the lowest parts of the Hudson Valley were similarly submerged beneath the waves of this sizable glacial lake. It was named after Albany because most of that town lies on the lake’s sediments. What you see at Flatbush is often flat. Sediments, mostly silt and clay, accumulate on the floor of a lake and create a flat lake bottom. Many of those bedrock masses of the Normanskill Formation emerged as islands in the old lake. After the waters drained, that lake bottom was left, high and dry, as a series of flat surfaces. All of Flatbush has this irregular terrain, but the lake bottom origins of this landscape are clear to an experienced geologist.

We drove around and enjoyed the experience. We were so aware that, most of the time, we were on the floor of an ice age lake. What a revelation! What a marvel to see that this part of the town was once submerged. Flatbush makes up an important part of the history of Saugerties. Its lake bottom soils were fertile and they were easy to plow. This vicinity was located near to the river so transport was a very practical matter. Thus, it came to be that Flatbush was the earliest part of the town to be settled. The vicinity is still dotted with very old farmhouses and equally old churches.

But we see a lake.

And you can see us. We will be speaking on this topic for the “Friends of Historic Saugerties” at their next meeting 2 p.m. Saturday, May 2, at the Saugerties Library. Join us, if you can.

Contact the authors at randjtitus@prodigy.net. Join their Facebook page “The Catskill Geologist.”