Abstract: The Granite Creek map area includes the southwestern section of the Gustavus Range. This area hosts summits approximately 2000 m in elevation. Granite and Albert creeks drain into Roop Lakes, through the wide, u-shaped lower Granite Creek valley. Keystone Creek flows in a narrow, bedrock-controlled valley. Lower Granite creek flows through the middle of the valley, depositing modern fluvial gravel and a blanket of organic material on the floodplain. Till from four alpine sources, as well as from the Cordilleran Ice Sheet (CIS), blanket the lower valley and intermix with glaciolacustrine sand and silt. Glaciolacustrine sediment can also be found capping moraines, and on valley walls above lateral moraines deposited when the CIS advanced up lower Granite Creek valley. Glaciofluvial gravel forms a proglacial fan where the former Granite Creek alpine glacier terminated and meltwater channels mark most former ice margins of the CIS. Till from the most recent glaciation is found in alpine glacier and Cordilleran Ice Sheet moraines, as well as in cirque valleys as blankets and veneers where preserved. Loess forms blankets on most gentle slopes, which allows for its preservation. Colluvium veneers, blankets, and fans form below steep slopes with active rockfall. Bedrock outcrops along steep cirque headwalls and in cirque valleys, as well as in Keystone Creek where fluvial downcutting processes are active. Stone stripes formed by frost heaving are found on gentle slopes. Flat upland surfaces host weathered bedrock and mud boils.

Authors: Steinke, J.L., Ward, B.C. and Bond J.D.

Keywords: albert creek, Granite Creek, Keno Hill, Mayo, Mt. Hinton

Map Scale: 1 : 20000

NTS Mapsheet(s): 105M14, 105M15

Citation: Steinke, J.L., Ward, B.C. and Bond, J.D., 2023. Surficial geology of Granite Creek, Yukon (part of NTS 105M/14 and 105M/15). Yukon Geological Survey, Open File 2023-02, scale 1:20000.

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