29.VIII (Written 7.VIII) Went with Ekacross the plain and part way up the Umana- nek - He called my attention to the dice- like embankments along one side - usually, if not always, the downhill side - if the furrows running over the subsoil drainage lines. Prob- ably connected with freezing and thaw- ing above the ice table. The subsoil drainage seems to follow cracks produce by shrinkage at and below the level of the ice table. Flat stones stand on edge and usually are arranged lengthwise of the furrows. Phenomenon of the unequal around frozen soil. Spec 682 + 683 are slabs of Hur- onian shale showing fossil mud cracks. Spec 684 Natrolite(-) Aragonite (:1 filling of crevice in the Huronian. Much of this material is scattered in frag- ments over talus slopes and plain - 8 August. Visited top of Umanak Butte with Ekblaw, Dr Hunt accompanying us to the base of the vertical 60 foot cliff formed by the edge of the diabase cap of the butte. Buttresses of Huronian