The Ordovician in the Mohawk Valley

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Views along West Canada Creek of Trenton Falls. The scene on the left looks down into the Denley Formation, with the Rust Formation in the foreground. The photograph at the right shows the contact between the Rust and Deley Formations, marked by the vegetation halfway up this waterfall. This vegetation is growing along the High Falls Ash, produced as a result of relatively nearby volcanic activity during the Ordovician.
Students from the University of Cincinnati observing layers of the Denley Formation. The Denley Formation here at Trenton Falls is a "calcilutite", a rock composed of calcareous mud deposited as turbidite flows. These 10 cm (~4 inch) thick lutites are interbedded with calcareous shale. The very rhythmic layers observed here lead some to believe that climatic cyclicity may have been at least partly responsible for their deposition.
An example of Isotelus maximus found in place in the Denley Formation. Isotelus lived in Ordovician times. Some specimens are among the largest trilobites found in the world. This guy probably ate mud directly from the sea floor. This fossil is black due to it being slightly "cooked" as a result of the pressures of many kilometers of rock that this fossil was once beneath. These overlying rocks have since been eroded away.
These circular-shaped fossils are Prasopora bryozoa found in situ in the Sugar River Formation, part of the Trenton Group. These are some of the largest examples of this marine animal found anywhere in the world. Bryozoans are microscopic sea animals that live in colonial structures, feeding on microscopic organisms floating in the water. Unlike trilobites, bryozoans are not extinct.

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