Reconnaissance surficial geology, Nonacho Lake, Northwest Territories, NTS 75-F .: M183-1/207-2014E-PDF

"Reconnaissance mapping, through aerial photograph interpretation and limited legacy field data in the Nonacho Lake map area, provides a basic understanding of surficial sediments and glacial history. Much of the area is characterized by rugged terrain, with steep-sided bedrock hills, and local relief reaching up to 100 m. Bedrock is well exposed in the western half of the map area. Till blanket, veneer and glaciofluvial outwash become increasingly more extensive in the central through to the eastern half of the map area, although bedrock can still be found in many regions. Fluted till, crag-and-tails and striations record ice advance to the west-southwest and southwest. Glaciofluvial corridors consisting of eskers, ice-contact sediments and scoured bedrock, record a generally southwestward meltwater flow across the map area during deglaciation. In the Nonacho Lake basin and Taltson River valley to the east, glaciolacustrine deltas and beaches are found at 320 m, 325 m, 335 m, and 350 m. In the Gray Lake basin, they occur at 330 m, 335 m, and 350 m. Pockets of glaciolacustrine sediments occur in several isolated lake basins, including Tejean, Porter, Vital, Halliday, Powder and Doranlakes. These are interpreted to be short lived, ice-dammed glacial lakes, with Nonacho Lake being the most extensive"--Abstract.

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