The Late Devonian Perry Formation was deposited in the St. Andrews and Blacks Harbour Basins and consists of red and green conglomerate, sandstone, siltstone, basalt, and minor amounts of limestone. The clastic sedimentary rocks are texturally and mineralogically immature and consist of subarkose, sub-litharenite, arkose, lithic arkose, and feldspathic litharenite.
The Perry Formation of the St. Andrews Basin is subdivided into five members. The Perry Formation of the Blacks Harbour Basin consists of six members. Interbasin outcrops consist of discontinuous sedimentary units which cannot be correlated with either basin.
Six sedimentary facies are interpreted as scree, alluvial fan, transitional lower fan, channel, overbank, and lacustrine environments. Facies analysis indicates lateral shift through these facies from alluvial fan to marginal lacustrine environments.
Analysis of directional current structures indicates a southeastern paleocurrent flow in the St. Andrews Basin with sources located primarily to the northwest. In the Blacks Harbour Basin, a paleoflow to the northwest supplied sediment from sources primarily to the southeast. Local sources supplied sediment for the interbasin deposits.