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Geology of Pennsylvania

The varied geology of Pennsylvania is representative of deep geologic times and events -- when geologic plates collided and formed mountains, when the land surface was under water or ice, and even during relatively quiet times.

The different landforms across Pennsylvania reflect these tectonic, erosional, and depositional processes, as well as the influence of the underlying bedrock.

Our geologic heritage can be seen at many outstanding places across the state. Heritage geology sites have been selected or nominated to illustrate many key geologic processes.