 At the mouth of Macklin Creek, the Kugruk River turns sharply, and above this place it flows in an east-west direction from its source at the east base of Kugruk Mountain.The bed rock along the Kugruk River is generally highly metamorphosed, consisting of mica-schists and calcareous schists, with large intrusions of greenstone.The greenstone is schistose, but has a porphyritic texture, the phenocrysts being hornblende, while the groundmass is made up essentially of epidote, hornblende, quartz, and chlorite, mostly secondary minerals.