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    Carboniferous - Conemaugh formation; Allegheny formation; Vanport limestone; Pottsville formation; Burgoon sandstone; Meadville shale; Cuyahoga formation (1)
    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)