Geology of the New York City Region

27. Route 209/Sawkill Road Outcrops Near Kingston, New York

Route 209 between Kingston and Port Jervis follows a series of southwestward-trending stream valleys (Esopus Creek, Roundout Creek, Basher Kill, and the Neversink River, north to south, respectively). These stream follow a natural saddle in the landscape called the Port Jervis Trough. This valley follows the strike of northwest dipping strata along the western side of the Great Valley, a valley that formed along the easily eroded shales of the lower Hamilton Group (late Middle Devonian). On the southeast side of the valley are high hills and mountains consisting of the older, more weathering-resistant dolomite and limestone formations of the Onondaga Formation and Helderberg Group, and the even more resistant sandstones and conglomerates of the Silurian Shawangunk Formation. To the northwest of the valley the land rises to the height of the Catskills Plateau where the mountaintops consist of more weathering-resistant sandstone and conglomerate of the Late Devonian Catskill Group (also called the Genesee Group). In the 19th Century, the lateral continuity of the streams valleys was utilized for the construction of the Delaware and Hudson Canal.

The shales of the lower Hamilton Group is well exposed along Route 209 in a series of large road cuts between Route 28 and Sawkill Road on the northwest side of Kingston (Figure 62 and 63). These road cuts consist dominantly of gray, friable shale with scattered thin ledges of sandstone and occasional silty limestone concretions. Fossil horn corals and spiriferid brachiopods and other marine invertebrate material are not abundant, nor are they typically in good condition. The brachiopods and corals show evidence of damage from being transported by storm or turbidity currents from shallower water into a deeper water setting (Figure 64).

Map of roadcuts near Kingston, New York
Figure 62. Location of roadside outcrops near the town of Kingston, New York.
Shale and sandstones in outcrops along Route 209, Kingston, New York
Figure 63. Outcrop of gray shales and thin sandstones of the Hamilton Group along Route 209 near Kingston, New York.
Fossil corals and brachiopods from the Hamilton Group, Kingston, New York
Figure 64. Rugose corals and spiriferid brachiopods from the lower Hamilton Group from near Kingston, New York.

A look at these outcrops are worthy of a brief stop on the way to the Catskills or the Shawangunks. Once again, there is often heavy traffic along Route 209, and the road cuts are very steep, and consist mostly of unconsolidated shale, so use extra caution. Other outcrops along un-posted side roads in the area may provide safer and easier access.

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Last modified: 3/11/2019