Sediments hosting the Guess Creek coal seams consist of Early to Middle Jurassic Hazelton Group sediments comprised of greywacke, siltstone, mudstone, tuffaceous greywacke and minor conglomerate. These sediments are poorly exposed except along sections of Guess Creek, where 35 metres of rock and overburden are exposed in vertical cliffs.

A prominent rhyodacite dike cuts metamorphosed sandstone, mudstone and coal, and is light grey in colour with a groundmass consisting of alkali feldspar and quartz with phenocrysts of biotite, quartz and plagioclase.

Four separate coal occurrences were identified and sampled in 1985. Individual coal seams are up to 1.8 metre in thickness and aggregate intervals, which include mudstone and fine-grained sandstone partings, measure up to 7 metres. The seams dip east and strike north-northeast. Seam D was traced over a strike length of 30 metres, and the other 3 seams were poorly exposed. Graphite was not detected in any of the coal seams.

Reflectance tests, using the mean maximum of vitrinite in oil techniques, indicated that samples from the seam near Guess Creek were of a high rank. Seam A was ranked as meta-anthracite, Seam B and D ranged from semi-anthracite to anthracite and Seam C ranged between low-volatile bituminous and high-volatile bituminous. The variation in rank between the seams is thought to be re-dated to the dikes that have locally, metamorphosed the coals. The degree of coalification reflects this thermal alteration.

In 2012, an aeromagnetic program was conducted over the Flute and Lennac properties by Riverside Resources (BC) Inc. The total covered area was 813 square kilometres and the total survey line coverage was 4,444 line kilometres (Assessment Report 33032, 33707F). The Guess Creek Coal occurrence was covered by this survey.

Refer also to Lennac property occurrences Thezar 81 (East) (093L 191), Thezar 75 (West) Suratt (Southeast) (093L 338), Jacob (093L 243).