The Horizon (formerly Five Cabin) coal property is located approximately 25 kilometres south-southwest of Tumbler Ridge. Tumbler Ridge is approximately 400 kilometres northeast of Prince George via Highways 97 and 29, and 105 kilometres southwest of Dawson Creek via Highways 97 and 52. The Horizon area is accessible up the Murray River Valley by British Columbia forestry roads, approximately 30 kilometres from the Quintette mine load-out site near Tumbler Ridge. Access to the Ridge area is a further 7 kilometres beyond Horizon by all-weather and seasonal exploration roads.
The Horizon area lies within a belt of Mesozoic strata that forms part of the Rocky Mountain Foothills of northeastern British Columbia. Coal seams with resource potential are found within Lower Cretaceous strata, in the Gething Formation of the Bullhead Group and the Gates Formation of the Fort St. John Group. The internal stratigraphy of this succession can be broadly characterized as an alternating sequence of marine shales and marine and non-marine clastic lithologies deposited from a series of transgressive and regressive cycles. The coal seams found within the Gething and Gates formations are believed to have formed within deltaic depositional environments. Thin, uneconomic seams may also be encountered within the Boulder Creek Formation above the Gates Formation and in the Minnes Group, below the Cadomin Formation, which occurs at base of the Gething Formation.
The Gates Formation (Fort St. John Group) is the major coal-bearing unit of the area and consists of siltstone, shale, sandstone, conglomerate and several cycles of coal deposition. It is generally subdivided into four sub-units, termed the Upper Gates member, the Babcock member, the Middle Gates member and the Quintette member. The Quintette member, approximately 80 to 90 metres thick, consists primarily of massive, fine-grained siltstones and sandstones. The Middle Gates member, approximately 90 to 100 metres thick, consists of a series of fining-upward sequences that culminate in coal development, and hosts all of the economic coal seams of the Gates Formation. The Babcock member is a channel-deposit sequence of massive sandstones, conglomeratic sandstones and chert pebble/granule conglomerates, averaging 20 to 30 metres thick. The Upper Gates member is a 30- to 40-metre series of shales and sandy shales with several thin, discontinuous coal seams. A very thin bed of ferruginous chert pebbles marks the top of the unit. Overall thickness of the Gates Formation is 270 to 300 metres.
The Lower Cretaceous Gething Formation (Bullhead Group) consists of alternating units of fine- to coarse-grained sandstone, carbonaceous shale, coal, siltstone and conglomerate. The upper contact is a thin bed of pebble conglomerate overlain by distinctive glauconitic, marine sandstones that form the base of the overlying Moosebar Formation (Fort St. John Group). Its thickness ranges from 120 to 200 metres.
The structure of the coal measures area is dominated by a regional-scale, northwest-trending syncline. The Five Cabin syncline is a relatively symmetrical open fold with generally less steeply dipping limbs than those of the Quintette trend to the east. The syncline plunges gently from the high ground at the Horizon-North Ridge tenure boundary, approximately 1.5 degrees to the northwest. At surface, in the Horizon-North Ridge area, the eastern limb dips 50 to 65 degrees to the west and the western limb dips 15 to 30 degrees to the east.
In 1980, surface mapping of the Five Cabin Creek coal property was conducted by Crows Nest Resources Limited, on behalf of owner Shell Canada Limited. The work was regional in scope and verified stratigraphy and structure within the area. In 1981, a geological program consisting of detailed surface mapping was completed and a helicopter assisted drilling program was initiated to test the coal-bearing Gates Formation. A 241-metre hole (81-1) was located on the west limb of the Five Cabin Creek syncline and the lower two-thirds of the Gates stratigraphy was cored, intersecting five coal seams. Coal quality results from this program suggested a medium-high volatile bituminous rank for this coal. In 1985, Crows Nest completed one diamond drill hole (FC85-1) to a depth of 306 metres. To date, 11 coal seams or zones have been identified based on present correlation between holes 81-1 and 85-l; of the 11 coal zones, only 8 are greater than 1 metre in width. Coal reserves for the Five Cabin Creek property are considered to have underground mining potential (ca. 1985, Coal Assessment Report 718).
Located in the north half of the Five Cabin property, the coal blocks are included in the Horizon group and form part of the Horizon mine area being explored and developed by Hillsborough Resources Ltd. In-place, surface-minable bituminous coal resources delineated in their report total 45 579 000 tonnes of measured and indicated resources and a further 8 176 000 tonnes of inferred resources. These coal resources have been estimated by Norwest based on 3-D geological models constructed by them, and within a 20:1 incremental cut-off ratio of bank cubic metres of overburden per tonne of coal (Stockwatch News Release - February 9, 2006). Based on the coal resources being delineated on these blocks, Hillsborough was proceeding with a feasibility study for the Horizon mine, with pit design and mine planning work based on a production level of up to 1 600 000 tonnes of coking coal product per year. Baseline environmental work was largely completed and the Horizon mine project was in the pre-application stage of the provincial Environmental Assessment process.
In 2005, the Horizon project entered the pre-application stage of the Environmental Assessment review process. Hillsborough Resources Ltd. completed environmental baseline studies towards the end of 2006. A scoping study outlined the potential for a 1 000 000- to 1 700 000-tonne per year operation with a 15-year mine life. Additional infill drilling, in support of a full feasibility study, and an underground bulk sample program were planned for 2007.
In 2006, Hillsborough Resources Limited continued to evaluate its Horizon (formerly Five Cabin) metallurgical coal property. The property covers the coal-bearing strata of the Gates and Gething formations. On the property, both formations are folded into a northwest-trending asymmetrical syncline, part of the regional-scale Five Cabin syncline, with typically gently dipping limbs. An extensive infill air-rotary drilling program, begun in 2005, further defined the Horizon block and expanded resources in the North Ridge area. The program identified six Gates Formation coal seams and three Gething Formation coal seams of economic interest. The density of drilling enabled calculation of an in-place coal resource. In July, the company released a combined surface and underground measured plus indicated coal resource for the Horizon property of 143 100 000 tonnes. An underground measured plus indicated coal resource of 49 660 000 tonnes was determined for parts of the three thickest seams exhibiting shallow dip angles (less than 16 degrees) above a depth of 400 metres. Seams 1.1 and 6.1 of the Gates Formation average 2.15 metres and 3.17 metres thick, respectively, and seam B2 of the Gething Formation averages 3.85 metres thick.
In 2007-08, 9610 metres of drilling were completed at Peace River Coal Inc.’s Horizon project, with an environmental assessment application expected to be submitted late in 2008. Approximately 42 000 000 tonnes of metallurgical and PCI coal resource have been identified. Production, both openpit and underground, could begin in 2010 at 1 200 000 tonnes per year from the gently folded coal measures in the Gates and Gething formations.
In 2009, Peace River Coal, the operating entity for the Peace River Coal Limited Partnership (73.8 per cent Anglo Coal Canada Ltd., 14.2 per cent Hillsborough Resources Ltd., 12.0 per cent Northern Energy and Mining Inc.), put its work program for the Horizon project on hold while the company modelled a new resource estimate that incorporated the Horizon, South Ridge and Barbara projects. Peace River Coal proposed to develop the Horizon block as a combined open pit/underground operation. Approximately 45 0000 000 tonnes of metallurgical and PCI coal resource have been identified historically, and this is expected to increase under the new modelling (Exploration and Mining in British Columbia 2009, page 28).
In 2012, the Horizon Ridge project (formerly the Five Cabin coal project) of Anglo American plc/Peace River Coal contained both Gates and Gething coal seams with potential for a 1 600 0000 tonnes per year underground operation over 20 years. The project was in the Pre-Application stage of the environmental assessment process.
In 2013 Anglo-PRC deferred exploration and development work at the Horizon Ridge project due to adverse market conditions.
In 2015 Peace River Coal Exploration undertook reclamation activities to return the areas disturbed to an end land use of wildlife habitat.
