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Geology -- Pennsylvania -- Armstrong County -- Maps (1) |
Geology -- Pennsylvania -- Butler County -- Maps (1) |
Geology -- Pennsylvania -- Venango County -- Maps (1) |
Geology -- United States --Maps (1) |
Natural gas -- Pennsylvania -- Armstrong County -- Maps (1) |
Natural gas -- Pennsylvania -- Butler County -- Maps (1) |
Natural gas -- Pennsylvania -- Clarion County -- Maps (1) |
Natural gas -- Pennsylvania -- Venango County -- Maps (1) |
Neogene - Carmichaels formation (1) |
Petroleum -- Pennsylvania -- Armstrong County -- Maps (1) |