The complex covers approximately 20 sq. Amphibolite encloses the BC ultramafic body, dominated by dunite with lenses of variably metamorphosed troctolite. Two meta-troctolite lithologies are present.
Hydration appears to be tied to phases of deformation.
Hydrated troctolite is most voluminous in boudin necks, the hinge regions of map-scale folds, and in shear zones, all regions where structural features may have favored local fluid infiltration. Strong interlayering and local gradation between units, along with geochemistry, indicate BC is a layered mafic igneous sequence. Gradations in the field between hydrated metatroctolite and amphibolite assemblages, corroborated geochemically, suggest that all units were originally part of the same complex. Trondhjemite dikes appear to crosscut BC units. The dunite map pattern may reflect Ramsay Type 2 fold interference.