Strong massive runs of hornblendic varieties stretch across the region in tolerably continuous lines, the general strike being nearly east and west.
hornblende | Hornblende |
A north-northwest-trending crustal segment transects from Kaminak Lake (central Hearne Domain) in the south to Yathkyed Lake (northern Hearne Domain) in the northwest, consisting of Archaen supracrustal belts that preserve mostly Archean mafic to felsic volcanic rocks (greenschist-grade supracrustal and granitoids), metamorphic cooling of hornblende and Proterozoic biotite.
The hornblende schist, found in contact with the serpentine mass directly to the North (at Ogo Dour) and to the South (at Pentreath and Church Cove) is the metamorphic remnant of basaltic intrusives into the upper crust.