The showing represents a klippe of Upper Triassic Sinwa Formation limestone resting on Lower Jurassic Laberge Group strata east of Trapper Lake. This tectonic outlier, resulting from the erosion of a thrust sheet, is part of the massive Sinwa limestone located along Kowatua Creek on the north side of the King Salmon thrust fault. The direction of movement along the King Salmon thrust fault has been from northeast to southwest and this small klippe of Sinwa limestone indicates a minimum displacement of about 16 kilometres.

The Sinwa limestone consists almost entirely of grey, usually petroliferous, white weathering limestone varying in thickness from a couple of metres to well over 600 metres. Minor interbedded chert and argillite is located near the base of the formation. The continuous band of Sinwa limestone (104K 072) extends from Kowatua Creek north- west to King Salmon Lake and across to Sinwa Mountain. The position of the Sinwa Formation limestone is unconformably overlying the Lower Jurassic Laberge Group, Takwahoni Formation due to a low angle thrust, the King Salmon thrust fault, that is localized along the base of the limestone.

The Sinwa limestone near Kowatua Creek lies immediately above the King Salmon thrust fault and is variably silicified, brecciated and contains fluorite veinlets associated with zones of intense altera- tion. Colourless, honey, purple and blue varieties of fluorite are present on the Tardis (104K 112).