The lithology of the area consists of greenschists, mica schists, quartzites, hornblende schists, amphibolites, garnet-amphibolites, serpentinites and porphyritic hypabyssal rocks
with andesitic to dacitic composition (Figure 1).
He pointed out many elements of dissimilitude between ophiolites and layered mafic igneous complexes, such as Skaergaard, including the scarcity of plagioclase in the ophiolitic peridotites, their relatively uniform mineral composition, the high-temperature deformation of peridotites, the occurrence of deformed chromite deposits and the paucity of hypabyssal rocks
of various compositions.
On Petit-de-Grat Island, the Glenkeen Formation consists of conglomerate and mafic volcanic and hypabyssal rocks
that are little metamorphosed, except in the contact aureole of the Petit-de-Grat Granite.