The Big Slide coal occurrence is located on the west bank of the Skeena River approximately 11 kilometres north of the village of Kispiox. A 100-metre slide scarp has exposed several coal seams.

Host rocks are folded and deformed shales, greywackes and conglomerates of the Lower Cretaceous Kitsuns Creek Formation, Skeena Group.

Three analyses were completed on three seams representing 60 to 90-centimetres of bituminous coal. Ash ranges from 18.24 to 27.24 per cent, fixed carbon from 51.26 to 68.34 per cent, volatile matter from 10.33 to 20.43 per cent and moisture from 1.07 to 2.10 per cent (Geological Survey of Canada Summary Report 1911, page 90).