The original Monkman property as configured in the 1970s was 80 kilometres long in a northwest direction and extended from just north of Kinuseo Creek at the north end, to Nekin Mountain near the Alberta border at the south end, and it covered almost 40,000 hectares. The project area included the Five Cabin, Onion Syncline, North and South Wapiti, Belcourt, Secus, Nekik, Saxon Extension and Duke Mountain blocks. This large property was broken up through a series of divestitures and acquisitions in the late 1980s, as outline in Coal Report 548. The current Monkman project (as of 2014) is a much smaller block (11070 hectares) held by Teck Coal Incorporated, consisting of the western side of the old Duke Mountain Block (as shown in Figure 1-1 of Coal Report 548). It is about 19.5 km long along its northwest striking length, from Kinuseo Creek to Wapiti River and 6 to 8 kilometres across in the east-west direction. The other blocks of the old Monkman property will be assigned their own MINFILE numbers.
The region is underlain by an assemblage of sedimentary rocks consisting mainly of continental margin and shelf facies rocks. This assemblage was deposited on and to the west of the ancestral North American craton. These sedimentary rocks, for the most part typical miogeoclinal facies, range in age from Hadrynian to Upper Cretaceous. Structurally these rocks are part of the Foreland Thrust and Fold Belt of the North American Cordillera.
The coal measures of the region occur mainly in Cretaceous sediments deposited unconformably on older miogeoclinal strata. These sediments were subjected to fold and thrust tectonics which also affected the older rocks.
Twelve coal seams of medium to high volatile bituminous rank occur in the Gates Formation (Fort St. John Group) of Lower Cretaceous age. The lower 9 seams (B1 to B9 which are considered economic) vary in thickness from 1.6 to 5.2 metres (on average) while the upper seams are generally less than 1 metre in thickness. The Gates Formation consists of a cyclic succession of sandstone, claystone, siltstone, conglomerate and coal (average thickness 248 metres but ranges from 190 to 290 metres), deposited in a deltaic setting.
The coal seams which exhibit good coking characteristics have variable numbers of partings (zero to numerous) with sulphur content less than 1 per cent, averaging approximately 0.42 per cent.
The oldest unit in the area is the Minnes Group which contains strata with numerous thin coal seams, none of which are greater than 1.2 metres in true thickness. These strata are overlain and underlain by coarse non-marine sandstone, claystone and siltstone.
Unconformably overlying Minnes Group strata is the Lower Cretaceous Cadomin Formation (Bullhead Group) followed by alternating nonmarine and marine sequences in the Bullhead and Fort St. John groups. The Gething Formation (Bullhead Group) (130 metres) contains similar lithologies to the Gates Formation including several coal seams of mineable thickness. The seam thicknesses are 2.5 and 4.1 metres in the upper and lower seams respectively. Sulphur is greater than 2 per cent in the upper seam which also includes numerous rock partings. Sulphur is less than 1 per cent in the lower seam and rock partings are common towards the base.
The Gates Formation is underlain by the marine Moosebar Formation (90 metres) and overlain by marine Hulcross Formation. The succeeding Boulder Creek Formation which consists of from 125 to 200 metres of non-marine sandstone, siltstone, claystone and conglomerate also contains some minor coal seams. All formations are part of the Fort St. John Group.
The structure of the property is a major northwest trending anticlinorium which is cut in the Duke Mountain block by a series of northeast or southwest dipping thrust faults. The anticlinorium is bounded on the east and west by thrust faults and complicated internally by zones of intense folding and faulting.
The Gates Formation in the Wapiti and Belcourt blocks occurs on the eastern limb of the anticlinorium or west limb of a syncline dipping northeast approximately 65 degrees.
The Nekik block contains Lower Gates Formation, underlain by Moosebar Formation and Gething Formation. Mineable seams include B3, B4, B7 and B7 in the Gates Formation and seam A in the Gething Formation. Thicknesses range from 1.70 metres (B9) to 4.18 metres (B3). Coal is sulphur-poor, less than 0.35 per cent sulphur with ash content approximately 10 per cent. Free Swelling Index for seams B3 and A are 3 and 2.5 respectively.
The structure of the Nekik block consists of a northerly plunging syncline with a gently dipping east limb (10 to 20 degrees west) and an overturned west limb (east limb of the anticlinorium to the west of the Wapiti and Belcourt blocks).
Run-of-mine reserves at a run-of-mine strip ratio of 6.3 for seven seams are 68,932,000 tonnes coal (Mine Development Assessment Process - Stage II Report, Volume 1, Monkman Coal Project, Petro-Canada, December 1981).
Canadian Dehua International Mines Group Inc (Dehua) commenced an exploration program in directly east of the current Monkman (Duke Mountain) project, in 2012 under the name Wapiti River Project.
As of December 2016, the property is held by Teck, reporting reserves of 24.3 million tonnes (Measured), 102.4 million tonnes (Indicated), and 122.6 million tonnes (Inferred) of metallurgical coal, in addition to 200 thousand tonnes (Measured), 700 thousand tonnes (Indicated), and 1.3 million tonnes (Inferred) of thermal coal (2016 Teck Annual Information Form, www.teck.com).