Vedder Mountain can be divided into three units: the eastern sediments, the crystalline rocks and the western sediments. Both eastern and western sediments are essentially unmetamorphosed whereas the crystalline rocks include both medium grade metamorphic rocks and saussuritized dioritic intrusive rocks. The crystalline rocks are bounded by steep southeast dipping faults. White mica-amphibole and garnetiferous white mica-amphibole schists and gneisses, amphibolite, epidote amphibolite and garnet-sphene-white mica schists comprise the metamorphic rocks. The mineral assemblages are typical of the almandite-amphibolite facies of Turner and Verhoogen (1960). Foliated diorites intrude (?) the metamorphic rocks. Basic contact zones, lighter colored diorite dikes, amphibole-feldspar pegmatites and small quartz diorite bodies are thought to represent various phases of differentiation of a parent magma. Pervasive saussuritization characterizes these rocks. In structural succession, the eastern sediments are comprised of chert, granitic and volcanic pebble and cobble conglomerates with plagioclase volcanic arenite interbeds; plagioclase volcanic arenite with conglomerate interbeds near the base of the unit and argillite interbeds near the top; and micro-volcanic arenite with interbeds of plagioclase volcanic arenite, argillite, chert and siliceous argillite with scattered, impure limestone pods. In structural succession, the western sediments consist of argillite; micro-volcanic arenite; chert lenticule arenite and volcanic chert arenite breccia which contain a band of impure, cherty limestone; argillite and chert. Vulcanism produced dacite porphyries which structurally underlie the sediments. The crystalline rocks comprise a tabular body believed to have been emplaced by faulting. Small, ellipsoidal serpentinite bodies lie along the southeast bounding fault of the crystalline slice. During emplacement of the crystalline slice, it appears that the sediments were pushed aside in what has been referred to as phase I deformation. Folding in the argillaceous units was "similar" in nature but in the more competent units it was "concentric." The eastern sediments comprise a synform with near horizontal northeast trending fold axis and steep southeast dipping axial plane. The western sediments comprise a steep, southeast dipping homocline. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

The major rock units within the area investigated are the Permian Chilliwack Group, the Upper Lower Jurassic - lower Middle Jurassic Cultus Formation, and the Upper Jurassic Lower Cretaceous Vedder Mountain Sediments. The Chilliwack rocks examined consist of four limestone units, a thick volcanic sequence, a conglomerate and argillites. The Cultus rocks consist of argillite, shale, graywacke and clastic limestone, The Vedder Mountain Sediments are graywackes, argillites and conglomerates. A tabular body of igneous rock and a schistose cherty rock are included in the sequence. The regional strike is to the north-east. Most of the rocks in the area are strongly fractured. The Cultus Formation is folded into a series of overturned isoclinal folds with axial planes striking north east and dipping south east. The strongly folded Chilliwack rocks are thrust over the Cultus rocks from the south and south east. The relationship of the Vedder Mountain sediments to the other major rock units is unknown. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate