A band of limestone of either the Lower Cambrian aged Mural Formation or the Hadrynian aged Cunningham Formation outcrops on Ptarmigan Creek and continues southeastward along the west side of the Fraser River for 5 kilometres. The band varies up to 800 metres in width and bedding strikes 120 to 150 degrees and dips 25 to 40 degrees southwest.
The band is composed mostly of pale blue to grey high calcium limestone with some pink and light brown streaks, patches and lenses of magnesian limestone containing disseminated dolomite with some quartz and muscovite. A sample taken across a bed of high calcium limestone (sample 98) and a second sample of brown magnesian limestone (sample 98A) contained (CANMET Report 811, p. 221, Samples 98, 98A):
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Sample 98 98A
CaO 54.58% 42.67%
MgO 0.87% 11.35%
SiO2 0.20% 0.32%
Al2O3 0.02% 0.11%
Fe2O3 0.07% 0.38%
Sulphur trace trace
A quarry was developed on the east side of Ptarmigan Creek, at the north end of a northwest trending ridge, 2.5 kilometres due west of Urling. Since the 1940's the quarry supplied limestone for rail- road ballast. Between 1967 and 1984 the quarry was operated by Quesnel Readi-Mix Cement Co. Ltd., producing railroad ballast and limestone for pulp mills near Prince George. A total of 626,544 tonnes of limestone were quarried by Quesnel Readi-Mix.
