 The basement at 5 km deep is the same as the Tyennan metamorphic rocks (Scotchfire Metamorphic Complex).Its oldest exposed rocks are from the Clark Group, of pelitic rocks, some with stromatolites, and evaporites, and overlaid with orthoquartzite.The Weld River Group lies above, starting with 0.5 km thickness of conglomerate and sandstone, then up to 3 km of dolomite, interbedded with sandstone, mudstone and diamictite.