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KNF Geology Overview
The Kootenai National Forest (KNF) is home to a myriad of geologic points of interest. From climbing the craggy peaks of the Cabinet Mountain Wilderness to prospecting in the streams which drain their rocky slopes, the KNF has something for everyone interested in geology.
Stone
The Kootenai National Forest is underlain by the Belt Supergroup. Rock in these formations is over 800 million years old, and was created when sedimentary layers deposited by a large inland sea lithified, or hardened, into rock. Exposures of the Prichard formation of the Belt Supergroup are found throughout the KNF. Stone from this formation, composed primarily of metamorphosed silts and muds, is sought after for use as building and landscaping stone. Many Districts on the Forest offer free-use stone permits to members of the public wishing to gather some of this stone. Stone collected under a free use permit is taken from specific sites on the Forest, and is limited to 2 tons per person. The stone gathered under this free permit may not be used for commercial purposes. Contact a District Office if you are interested in a Free-Use Stone Permit.
Rock Climbing
The most well-known rock climbing destination on the Kootenai National Forest is the Stone Hill Climbing Area along the Koocanusa Reservoir. The exposures of Prichard formation at Stone Hill offer a unique experience for climbers of all levels. The area offers a good range of easy to moderate climbs for the intermediate climber. The Stone Hill climbing area is located at mile marker 51 on Highway 37 along Lake Koocanusa. The majority of Stone Hill’s more than 500 climbs are challenging, rating 5.10 and up, but there are also a large number of easy and moderate climbs. The climbing season is generally late February through late October.
Kootenai Falls
The trail to the Kootenai Falls is accessed from the trailhead on Highway 2 located between Libby and Troy. This short hike into the river canyon offers some interesting exposures of geologic features which are part of the Mount Shields formation of the Belt Supergroup. These features include ripple marks, salt casts, mudcracks, and fossil stromatolites. The stromatolite bed located near the footbridge over the Kootenai River is composed of vertically stacked “heads” of fossilized algae which are 12 to 24 inches wide and more than 3 feet high.
Mining
Historically, the KNF was home to many mining operations which made up the mining Districts of Libby, Cabinet/West Fisher, Silver Butte/Vermillion, Trout Creek, Troy, and Wolf Creek. Most mining operations on the KNF aim to recover gold, silver or copper. The scale of operations varies from individuals panning for gold in the creeks, all the way up to the Troy Mine, a large-scale underground copper/silver mine which operates near Troy, MT. Proposed mining operations on the KNF include the Montanore and Rock Creek Mines, near Libby and Noxon respectively.
There are many historic mining features on the KNF ranging from equipment, mill sites, portals, abandoned workings, etc. It is important to understand that abandoned mines lands (AML) can be hazardous and unsafe. Some of the hazards that may be present at AML sites include: unsafe mine shafts & highwalls, deep pools of water, dangerous gases, unstable explosives, old buildings and machinery. Please respect the warning signs that are posted throughout the Forest at known hazardous AML features, and realize that not all potentially hazardous features are known or marked, so use caution when these sites are encountered. Mining operations continue to this day in some of these historic mining districts.
The public can enjoy numerous mining and prospecting activities on National Forest System (NFS) lands. Try visiting the Libby Recreational Gold Panning Area, or even staking a claim of your own. See our Prospecting and Gold Panning Area pages for more information.
