Cade 758 Microtus miinus August - Summary of occurrence at Ob filak Lake - also other microturics. M. miinus is the dominant microturic at this locality. It apparently has occurred at reached high densities on the fans and steep slopes of the sides of the wally. Microturic sign - runworm and holes, presumably of M. miinus - are conspicuous all the way to 6,000 feet. M. miinus appears to be absent from the intermediate zone from the base of the fans to the river Terrace. This ground is typically damp to wet with mostly a dwarf shrub- heath-lighers-Eriophyllum complex directed by microturic damages of willows, redges & quanes. In this area- especially along the lush drainages - Lemmyns and M. oecosomus occur sparse. On the flood plain and on the old river terrace - especially along the banks of old stream meanders - M. miinus again reaches a high density, but perhaps not so high up on the slopes, and the flood plain habitats may serve mainly as spill- over areas for surplus animals forced out of the slope - fan terrace. Impaces