Approximately six days were spent in the Miers Valley on a reconnaissance geological survey of the basement rocks so that Korsch could obtain a working knowledge of these rocks. The Miers Valley was selected because of its accessibility, facilities (Wannigan) and because a 1:25000 geological map which included the northern wall of the Miers Valley had been produced in the 1980-81 field season by G. Mortimer, F. Reid and S. Simmons (see report by Mortimer, 1981).

During our stay in the Miers Valley we were able to examine most of the rock units shown on Mortimer's map. Metasedimentary rocks of the Koettlitz Group include a wide variety of parent lithologies including pure and impure limestone, shale, sandstone, quartzose sandstone and intercalated basaltic volcanics. These rocks have been regionally metamorphosed to amphibolite facies and then suffered localised contact metamorphism during emplacement of various granitic plutons.

Deformation of the metasedimentary rocks produced isoclinal folds, an excellent example of which is well displayed in the Salmon Marble on the north wall of the Miers Valley. A second deformation refolded the first generation structures.

Granitic rocks observed in the field included the Buddha Diorite, Dais Granite, Miers Granite, Rivard Diorite and Grey Granite along with unnamed aplite, pegmatite, lamprophyre and basalt dykes. Wherever contacts were exposed good evidence for the intrusive nature of the plutons was observed. Detailed field descriptions of all the units can be found in Mortimer (1981).

During our reconnaissance study of the ridge between the Miers and Marshall valleys we found that the map of Mortimer (1981) stood up well under scrutiny, although minor modifications should be made. The biggest problem we faced was in the recognition of various plutonic units which in places seemed to grade into each other, but this will be overcome by experience with these rocks. One must question Mortimer's use of the term "Penance Pass Formation" as a suitable term - "Hobbs Formation" already exists in the literature and only needs redefining rather than the introduction of a completely new term.

This study represented an introduction to the basement rocks for Korsch, who is developing a programme to study various aspects of the basement geology over the next few field seasons.