Sunday, 30 August 2020


The South Chilcotin Mountains Park has been home, hunting ground and trade route to local First Nations for thousands of years. The area falls within the territory of three Nations: Tsilhqot’in, St’at’imc, and Secwepemc. 

My interest in this part of the Chilcotin's is the geology and well-preserved fossil specimen it yields. To others, this region is a place to fish, hunt, collect berries and travel across as a trading route. While the area is now a protected park, it still sees a fair amount of recreational use.

Deer and mountain goats were hunted here for their meat and hides. Wool and horns were harvested from the region's goats for use as salmon spears. Special ceremonies were performed before hunting grizzly and black bear to honour their spirits and to thank them for the gift of their meat, fat and fur. Though common today, moose did not move into the area until about 1920. 

The skins of hoary marmots were used for robes and blankets and as trade goods. These were hunted in late summer or early fall after they had hibernated; the meat was smoked and the fat was particularly prized. Dash Hill, Cardtable Mountain, Eldorado Mountain, Teepee Mountain, and Graveyard Creek are known hunting sites.

South Chilcotin Mountains Park is situated in an area of complex geology that straddles the boundary between the southeast Coast Mountains and the Chilcotin Plateau. The geological history is one of the ancient ocean deposits, tectonic plate movement, faulting and mixing of rocks and layers of rocks, deposition of sedimentary rocks in shallow-marine basins, upwellings of granitic rocks and lava flows. Landscape features in South Chilcotin Mountains Park reflect the many complex geological formations that underlie it.

Sedimentary rocks are found in the heart of South Chilcotin Mountains Park through Upper Gun and Tyaughton Creeks and Relay and middle Tyaughton Creeks. They also form the height of land from Lorna Lake to Vic Lake in Big Creek Park.

Heidi Henderson and John Fam, VanPS
The serrated mountains in the Slim, Leckie and upper Gun creeks are underlain by granitic rocks that are a characteristic feature of the Coast Mountains. 

These granitic rocks are components of the continental margin magmatic arc related to subduction of oceanic rocks along the plate boundary to the west. This is a similar process to that still going on today and generating volcanic rocks such as Mt. Baker and Mt. St. Helens.

Volcanic rocks of Early to Middle Eocene (58 – 50 million years ago) age formed in several small volcanic centres scattered through the park. The most spectacular exposure is found at Mount Sheba, on the north side of Gun Creek.

The youngest rocks are part of the great lava flows of 16 to 1 million years ago that formed the extensive Chilcotin Plateau. Outlying remnants of these lava flows occur in the area of Teepee, Relay and Cardtable Mountains. On Relay Mountain the basalts are up to 350 metres thick.

Fossils are an important feature of South Chilcotin Mountains Park and demonstrate the marine origin of many of the sedimentary rocks. Well-preserved late Triassic marine fossils (ammonites and bivalves) are found in the Tyaughton Creek area. Lower and Middle Jurassic rocks in this same general area are also locally rich in fossils — mainly ammonites. The Relay Mountain Group is in part extremely rich in upper Jurassic and Lower Cretaceous fossils. Fossil-rich parts of the Relay Mountain Group are found around upper Relay Creek, Elbow Mountain and on the low bluffs northwest of Spruce Lake.

The faunal sequences based on ammonoids established for the Late Hettangian to Early Sinemurian interval in the Western Cordillera found here match-up rather nicely to those found in Nevada, USA.