An elongate, north trending, fault bounded block (horst) of middle to Upper Permian Marble Canyon Formation (Cache Creek Complex) forms a series of carbonate bluffs between White Rock and Blue Earth creeks on the east side of the upper Hat Creek valley, 22 kilometres southwest of Cache Creek. The block is 9.5 kilometres long and up to 1.7 kilometres wide. Bedding strikes 010 to 055 degrees (commonly 025 degrees) and dips 22 to 86 degrees northwest.

Mapping and sampling over the northern half of the block revealed mostly light to dark grey, rarely white or black, massive to bedded, fine to medium grained limestone, magnesian limestone and dolomite, with variable amounts of white calcite as blebs, veinlets and streaks. Rare beds of quartzite, shale and sedimentary breccia are present within these carbonates. Some of the limestone and dolomite beds are quite siliceous.

A sample of dark grey, fine-grained limestone taken just south of White Rock Creek near the north end of the block analysed 55.50 per cent CaO, 0.18 per cent MgO, 0.26 per cent SiO2, 0.58 per cent Al2O3, 0.18 per cent Fe2O3, 0.20 per cent TiO2, 0.02 per cent Na2O, 0.02 per cent K2O, 0.02 per cent P2O5 and 42.49 per cent ignition loss (B.C. Hydro Report SE 8221, Table 3-1, Sample 19). Five 20- kilogram bulk samples collected further south yielded the following percentage range of values (B.C. Hydro Report 8221, Addendum, Samples 30 to 35):

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CaO 31.77 - 53.32

MgO 1.91 - 10.59

SiO2 2.79 - 27.20

Al2O3 0.02 - 0.03

Fe2O3 0.10 - 0.26

TiO2 0.02 - 0.03

Na2O 0.02 - 0.10

K2O 0.02 - 0.03

P2O5 0.02 - 0.07

Ig.Loss 31.96 - 40.18

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The deposit was mapped and sampled by B.C. Hydro between 1981 and 1983 during a search for dolomite in the Hat Creek area to scrub gases from a proposed coal-fired electrical generation plant utilizing pressurized fluidized bed combustion.