The Ashington Coal mine is situated on the north bank of the Tulameen River, 70 metres southwest of the north end of the Tulameen River bridge in the town of Princeton.

This coal deposit occurs near the centre of the Princeton Basin, a northerly trending half-graben superimposed on volcanics and sediments of the Upper Triassic Nicola Group. The basin is separated into a northern and southern area by the gentle, northwest-striking Rainbow Lake anticline. The southern area, in which this occurrence lies, is a structural depression with beds dipping 10 to 20 degrees south near Princeton, and gently east between Asp (China) Creek and the Tulameen River. The basin is bounded and cut in places by a number of approximately north to northeast-striking, westerly dipping faults. The main faults are the Asp Creek fault and the Boundary fault.

The Ashington mine is hosted in a sequence of sandstone, shale, waterlain rhyolite tephra (tuff) and coal, up to 2000 metres thick, comprising the Eocene Allenby Formation (Princeton Group).

The coal seam at the Ashington mine strikes approximately 090 degrees and dips 15 degrees south. The seam is 1.8 metres thick and contains thin bands of shale and dirty coal. Underground workings followed the coal westward for 137 metres.

The deposit is overlain by a bed of clay, 6 metres thick, which is in turn overlain by sandstone and conglomerate. The overlying clay is greyish white, very fine grained, brittle, and has a conchoidal fracture. A sample of the clay shows a very low shrinkage of 0.6 per cent during air drying. Firing characteristics are as follows (Geological Survey of Canada Memoir 47, page 53):

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Cone Fire shrinkage Absorption

(per cent) (per cent)

010 2.4 32.50

03 13.6 5.10

1 15.7 0.70

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The deposit was tunnelled and drilled by Ashington Coal Company Ltd. in 1929 and 1930. The company produced 22 tonnes of coal, while exploring this deposit.