The Crouse Harbour and Cape Rouge formations make up a small, isolated outlier of the Carboniferous Maritimes Basin which is situated on the east side of the Great Northern Peninsula of Newfoundland. They represent nonmarine deposition in a portion of a fault-bounded sub-basin, similar to other known Lower Carboniferous sub-basins of Atlantic Canada. Lithofacies include units of braided fluvial, pebbly coarse sandstone and pebble conglomerate, and shallow lacustrine, laminated mudstone and dolostone. Rocks dominated by finer facies (Cape Rouge Formation) and those dominated by coarser facies (Crouse Harbour Formation) intertongue at some localities. Spore assemblages from both formations are assigned to the Spelaeotriletes cabotii Assemblage Subzone (early T-II) of the Vallatisporites vallatus Assemblage Zone of the late Tournaisian. These units are, therefore, in the same assemblage zone and are facies-equivalents to the upper Albert Formation of New Brunswick, and the Horton Bluff and Strathlorne/Ainslie formations of Nova Scotia. The oil seeps reported by earlier workers are located near major faults, and on joint planes within thin dolostones that are intercalated within black organic-rich (commonly 1 to 2%, ranging up to 4% Total Organic Carbon), intermittently-anoxic lacustrine mudstones. The latter, or more deeply buried equivalents, are the probable source of the hydrocarbons. A combination of maturity indices indicate that the predominantly Type I organic matter is in the later stages of the oil window (1.0 to 1.2% vitrinite Ro). Some samples contain two or more types of homogeneous organic matter, as indicated by differing textures and reflectances, suggesting either several phases of bitumen generation and migration or differing compositions of precursor organic matter. It is possible that petroliferous rocks of similar, or slightly older, age are present in the offshore area beneath adjacent White Bay.