Drift Exploration and Surficial Geology of the Cl Usko River and Toil Mountain Map Sheets

This report dcscrihcs the details of field inucstigxions carried out during I :%I OOO-scale mapping of surficial gsology on NTS map shet%s Y3ClY and I h t,Figurr 4. I I I ), The area has good tninct,al potential but cnpluratiun is hindcrcd in !nany areas hy a lhick cover of sorficial sediment (Tipper. 1971). Surficial geology maps at 3 xale of I:SO 000 are available for the anx directly north and east of thcsc map sheets but none exert folthe current study ww The aim 01 this project is to pr~:widc I :SO 000--sc;dc maps and surficial gculogy interpretat on that will assist lnlineral exploration. Map products will be of two type>: a terrain map. and a surficial exploration potential map. ‘Thar maps and an accompany~nf report will he published scparat~ly. The project is fun&xi by the Canada British Columbia Mineral Devrlopment A&w:ment I YY I 1’9% The only prior wrficial gcolupy map puhlishcd f<x the urea was based on fieldwork during the IYSOs and lU60\ conducted mainly f’ex the purp~wz 01 mapping bedrock (Tipper, I97 I). The lmap was published at a scidc of I :2X) 000 and described mainly surficial geology features. hut snot materials. Tipper’s study wns conducted prim to lugging in the wei, and so could ,no, take advantage of the ,many road exposures of surficial material now a\ailahlc. Tipper intcrprctcd an early. generally nwthward, glacial Ilow through the :,tudy area. which he equated with the Fraser glaciation of the Cordilleran ice sheet. Later eastward and northeastward ice lltw in the wertern part of the arca was interpI-eted iis readvancns hy Fruscr ice. A% ice thinned during deglacintion. topography had an incvxsing cffcct on ice-flow direction. causing dcflcctrons ar<lund tupogruphically high arei~?. Tipper descrihcd abundant sand und gravel dcpusils prrxnr in eskers and ~mclt~at~r channels. that he sugfcstcd developed from a stagwu~t ice amass during deglaciation He ;dso mapped the qqmrnimate limit US rcadvancing ice based on the position of “pitted terrain”. and the different directixx of ice-flow indicators on cithcr side of this terrain. This feeaturc trimsrc~s the western? part of the ,map area.