The Mount Merrick, Jilg (MINFILE 093P 010) and Triangle (or Rocky Creek)(MINFILE 093P04) prospects were all part of the British Petroleum Exploration's Sukunka North project area in 1979 (Coal Assessment Report 671). The Mount Merrick occurrence lies at the western edge of the project area in the footwall of the Merrick Thrust.

Coal seams occur in the Juro-Cretaceous Minnes Group and Lower Cretaceous Gething Formation (Bullhead Group) consisting of sandstone, siltstone, mudstone and carbonaceous shale. Minnes Group coal occurs in the Bickford Formation and consists of two seams, the Merrick and Rusty, each on average 2 metres thick within 30 metres of the Cadomin Formation (Bullhead Group) base. The seams are laterally extensive over considerable distances in the Merrick block but deteriorate and thin out across the depositional strike within the Jilg/Triangle regions; and in the Beattie Peaks Formation (Minnes Group). The latter are generally thin and uneconomic, with the exception of the Hill seam which is over 2.5 metres thick and occurs within an isolated high terrain.

The Gething Formation coal occurs in two coal zones, each 3 to 4 metres thick. Gething Formation strata is present quite extensively in the Sukunka North block, however within the Jilg, Triangle and Merrick blocks the Gething Formation sediments are confined to small tight folds and only the lowermost strata, containing at most 2 seams 0.5 to 1.5 metres thick in the Merrick block, are preserved.

The structure consists of northwest trending folds and thrust faults. The Jilg block is dominated by tight folds and a northeast dipping thrust fault to the west. A fold in the westernmost area of the Merrick block is overturned.