The Round Island coal prospect was explored by Consumers Coal Co., Ltd. in the early 1900's. The coal seam is part of the Upper Cretaceous Nanaimo Group and is exposed in a northwest trending, northwest plunging relatively broad anticline.

The coal seam which outcrops in the southern part of Round Island, varies from 0.6 to 2.0 metres in thickness. The coal is underlain by a sandy shale floor and is overlain by sandstone. The seam may represent the Douglas Seam of the Pender Formation, however, insufficient information is available to verify this.