The Unit 9 Wavy Horizon, Eastern Layered Intrusion, Rum. (a) Undulatory contact between troctolite and the overlying dark, pyroxene-rich gabbro. (b-e) Crossed polars photomicrographs of Unit 9 lithologies. (b) Peridotite with underlying large poikilitic clinopyroxene. (c) Allivalite (troctolite) with feldspar lamination. (d,e) Pyroxene-rich gabbro immediately above troctolite at the Wavy Horizon. See Emeleus and Troll (this issue).