The Denniston Plateau is a north west dipping plateau bounded to the west by the Papahaua Overfold / Kongahu Fault zone, and to the east by the Mt William Fault.

The coal measures consist of a fluviatile sequence of fine to very coarse sandstones, siltstone, mudstone and coal seams.

The main coal seam varies in thickness from less than 1m thick up to 14m thickness locally.

Depth of cover varies from 0m at outcrop to over 150m at the eastern margin of the Mt William Fault. Inferred and Indicated resources include coal up to 130m below surface, while the measured resource includes coal up to 75m below surface.

The deposit roughly covers a 6.5km by 4.5km area. The model is bounded by the Escarpment Fault to the south, the Waimangaroa Gorge to the north, and the Mt William Fault to the east.

Production from Escarpment began in 2014 and the mine was placed in care and maintenance in May 2016. The preferred mining method is conventional truck and shovel open pit mining at an appropriate bench height.

Production from Escarpment began in 2014 and the mine was placed in care and maintenance in May 2016.

The ROM coal produced at Escarpment is not washed resulting in 100% yield for the operation. Product coal specifications include ash, sulphur, moisture and calorific value.