Penn Dixie Cluster

Penn Dixie Fossil Park

400 million years ago planet Earth was much different than it is today. Seas covered much of New York State. The environment at the time formed rock layers that included fossils of many tropical marine organisms such as brachiopod shells, corals, crinoids (sea lilies) and a form of sea sponges. The Penn Dixie Fossil Park, in western New York, and Thacher Park, located in eastern New York, both contain examples of this past ocean environment. The Penn Dixie Fossil Park has layers of shale that were deposited in deep water about 380 million years ago but are now exposed at Earth’s surface. Thacher Park consists of sedimentary rock layers such as limestone, sandstone and shale, that began forming about 410 million years ago as a result of deposition of sediments at a time of changing sea levels. This area was eventually uplifted, exposing these layers and the fossils in them.

​The maps below show the inferred location of the continent of North America, shaded in black, relative to other continents, 360 million years ago and the present day location of the continents.

Multiple Choice

Which piece of evidence could be used to support the claim that New York State was covered by water about 400 million years ago?

• Both Penn Dixie Park and Thacher Park have eroded surfaces.

• Penn Dixie Park has rock layers similar in age to those in Thacher Park.

• Both Penn Dixie Park and Thacher Park contain marine fossils in the exposed rock layers.

• Both Penn Dixie Park and Thacher Park were located over the equator.

Open Ended

The continent of North America is inferred to have moved from its location 360 million years ago to its present-day location. Provide one piece of evidence that supports this past plate motion.

Multiple Choice

Penn Dixie Fossil Park and Thacher Park can be used to organize the geologic history of New York State. Which evidence can be used to support this claim?

• Analysis of rock strata (layers) and fossils at Penn Dixie Park and Thacher Park.

• Analysis of the present day elevations of Penn Dixie Park and Thacher Park.

• The distance of Penn Dixie Park and Thacher Park from the equator.

• The distance of Penn Dixie Park and Thacher Park from Lake Erie and Lake Ontario.

​The cross-sections below show the rock formations at Penn Dixie Fossil Park and Thacher Park. The names of some rock formations and types of rock are shown.

Open Ended

Geoscience processes have changed Earth’s surface. Interpret the cross-sections of Penn Dixie Park and Thacher Park to identify two pieces of evidence from either cross-section that supports this statement.

Open Ended

The surface bedrock at Penn Dixie Fossil Park and Thacher Park are approximately the same geologic age. Identify one piece of evidence shown in both cross-sections that supports this statement.