The Thompson Plateau forms the southern portion of the

Interior Plateau The Interior Plateau comprises a large region of the Interior of British Columbia, and lies between the Cariboo and Monashee Mountains on the east, and the Hazelton Mountains, Coast Mountains and Cascade Range on the west.''Landforms of British C ...

British Columbia British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, for ...

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by to ...

, lying to the west of Okanagan Lake, south of the

Thompson River The Thompson River is the largest tributary of the Fraser River, flowing through the south-central portion of British Columbia, Canada. The Thompson River has two main branches, the South Thompson River and the North Thompson River. The ri ...

and east of (although never adjoining it) the

Fraser River The Fraser River is the longest river within British Columbia, Canada, rising at Fraser Pass near Blackrock Mountain in the Rocky Mountains and flowing for , into the Strait of Georgia just south of the City of Vancouver. The river's annual ...

. At its most southern point the plateau is squeezed by the mountainous terrain of the

Cascade Range The Cascade Range or Cascades is a major mountain range of western North America, extending from southern British Columbia through Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as the North Cascades, ...

abutting closer to the Okanagan Valley. Its southwestern edge abuts the

Canadian Cascades The North Cascades are a section of the Cascade Range of western North America. They span the border between the Canadian province of British Columbia and the U.S. state of Washington and are officially named in the U.S. and Canada as the Cascad ...

portion of that extensive range, more or less following the line of the

Similkameen River The Similkameen River runs through southern British Columbia, Canada, eventually discharging into the Okanagan River near Oroville, Washington, in the United States. Through the Okanagan River, it drains to the Columbia River. The river is said ...

, its tributary the

Tulameen River The Tulameen River is a tributary of the Similkameen River in the Canadian province of British Columbia. The Tulameen River is part of the Columbia River drainage basin, being a tributary of the Similkameen River, which flows into the Okanagan Riv ...

, and a series of passes from the area of

Tulameen, British Columbia Tulameen, originally known as Otter Flat, is a small community in British Columbia, Canada, about 26 kilometres northwest of the town of Princeton on the Crowsnest Highway (Hwy 3), and about 185 kilometres northeast from the city of Vancouver, Br ...

to the confluence of the

with the

Nicoamen River The Nicoamen River is a tributary of the Thompson River in the southern Interior of British Columbia, Canada, located upstream from its confluence with the Thompson at Lytton. The Nicoamen forms the extreme northeast boundary of the Cascade Mount ...

, a few kilometres (miles) east of

Lytton, British Columbia Lytton is a village of about 250 residents in southern British Columbia, Canada, on the east side of the Fraser River and primarily the south side of the Thompson River, where it flows southwesterly into the Fraser. The community includes t ...

, which is in the Fraser Canyon. Its northeastern edge runs approximately from the city of

Vernon, British Columbia Vernon is a city in the Okanagan region of the Southern Interior of British Columbia, Canada. It is northeast of Vancouver. Named after Forbes George Vernon, a former MLA of British Columbia who helped establish the Coldstream Ranch in nearb ...

through the valley of Monte Creek to the junction of the same name just east of the city of

Kamloops Kamloops ( ) is a city in south-central British Columbia, Canada, at the confluence of the South flowing North Thompson River and the West flowing Thompson River, east of Kamloops Lake. It is located in the Thompson-Nicola Regional District, w ...

. Northeast of that line is the

Shuswap Highland The Shuswap Highland is a plateau-like hilly area of in British Columbia, Canada. It spans the upland area between the Bonaparte and Thompson Plateaus from the area of Mahood Lake, at the southeast corner of the Cariboo Plateau, southeast towar ...

. Some definitions include the

Bonaparte Plateau The Bonaparte Plateau, in British Columbia, Canada, is a sub-plateau of the Thompson Plateau which extends to the Quesnel River and lies between the Cariboo Mountains on the east and the Fraser River on the west. The Thompson Plateau is itself a ...

to the north, which lies in the angle of the Thompson and

Bonaparte River The Bonaparte River is a tributary of the Thompson River, joining it at the community of Ashcroft, British Columbia. The river is about long, including the length of Bonaparte Lake. Rising on the Silwhoiakun Plateau to the northwest of Kamloops, ...

s, and south of the uppermost reaches of that river and a small tributary of the North Thompson, Lemieux Creek. The dominant landscape of the Thompson Plateau is a high, almost plains-like rangeland fairly heavily forested with subalpine forest and tamarack swamp where there exists a significant cattle ranching industry, but plunging steeply to the valleys of the Thompson and Okanagan on its outer perimeter which feature more semi-arid landscapes that include

rattlesnakes Rattlesnakes are venomous snakes that form the genera '' Crotalus'' and '' Sistrurus'' of the subfamily Crotalinae (the pit vipers). All rattlesnakes are vipers. Rattlesnakes are predators that live in a wide array of habitats, hunting small an ...

, a ground-creeping variety of prickly pear cactus,

sagebrush Sagebrush is the common name of several woody and herbaceous species of plants in the genus '' Artemisia''. The best known sagebrush is the shrub '' Artemisia tridentata''. Sagebrushes are native to the North American west. Following is an al ...

, and

tumbleweed A tumbleweed is a structural part of the above-ground anatomy of a number of species of plants. It is a diaspore that, once mature and dry, detaches from its root or stem and rolls due to the force of the wind. In most such species, the tumbl ...

, in addition to fruit growing operations that often rely on irrigation. In its core is the broad and open rangeland of the

Nicola Valley The Nicola Country, also known as the Nicola Valley and often referred to simply as The Nicola, and originally Nicolas' Country or Nicholas' Country, adapted to Nicola's Country and simplified since, is a region in the Southern Interior of British ...

, at the focus of which is the town of

Merritt, British Columbia Merritt is a city in the Nicola Valley of the south-central Interior of British Columbia, Canada. It is northeast of Vancouver. Situated at the confluence of the Nicola and Coldwater rivers, it is the first major community encountered afte ...

. Towards its southern edges, the plateau is fairly mountainous and includes the ski area at

Apex The apex is the highest point of something. The word may also refer to: Arts and media Fictional entities * Apex (comics), a teenaged super villainess in the Marvel Universe * Ape-X, a super-intelligent ape in the Squadron Supreme universe *Apex, ...

(west of

Penticton Penticton ( ) is a city in the Okanagan Valley of the Southern Interior of British Columbia, Canada, situated between Okanagan and Skaha lakes. In the 2016 Canadian Census, its population was 33,761, while its census agglomeration The ce ...

), as well as the small but rugged Kruger Range which runs south from there to the confluence of the Similkameen and Okanagan Rivers.

History

The Thompson Plateau contains Nicola Athapaskan, Nlaka'pamux and

Syilx The ''Syilx'' () people, also known as the Okanagan, Okanogan or Okinagan people, are a First Nations and Native American people whose traditional territory spans the Canada–US boundary in Washington state and British Columbia in the Okanagan ...

settlements. The Nlaka'pamux peoples of the plateau were known as Cawa'xamux or Tcawa'xamux Nlaka'pamux settlements include: * Kaptciʼtcîn * Caʼxanîx * xˑûʼtxˑûtkawêꞀ * xanᴇxᴇwêꞀ * Qaiskanaʼ or Koiskanaʼ * Nˈaʼiᴇk or Nˈēʼiᴇk * Tsuluʼs or Suluʼs * Ptîʼtᴇk or Pᴇtuʼtᴇk * Nsiʼsqᴇt * Ntsʟaʼtko * Zuxt * Quîltcaʼna * Ntcêʼkus or Stcêʼkus Syilx settlements include: * QêʼꞀamix or ʟkaꞀamix * Spaʼxᴇmîn * Komkonaʼtko * Zuʼtsᴇmîn or Zuʼtsamîn

Geology

The rocks underlying the Thompson Plateau originated in the

Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the contine ...

and were appended to the

North American Plate The North American Plate is a tectonic plate covering most of North America, Cuba, the Bahamas, extreme northeastern Asia, and parts of Iceland and the Azores. With an area of , it is the Earth's second largest tectonic plate, behind the Paci ...

in the

Mesozoic The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretace ...

. These rocks were pervasively intruded by magmas now forming granitic rocks. These upland surfaces are now bordered by prominent valleys over 1000 metres (3000') deep. This

peneplain 390px, Sketch of a hypothetical peneplain formation after an orogeny. In geomorphology and geology, a peneplain is a low-relief plain formed by protracted erosion. This is the definition in the broadest of terms, albeit with frequency the usage ...

was overlain by thin sheets of plateau basalts formed from the

Chilcotin Group The Chilcotin Group, also called the Chilcotin Plateau Basalts, is a large area of basaltic lava that forms a volcanic plateau running parallel with the Garibaldi Volcanic Belt in south-central British Columbia, Canada. Predominantly, during Mio ...

lavas that flowed ten to fifteen million years ago. The area was occupied by

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...

glaciation, and a thick mantle of

glacial drift In geology, drift is a name for all sediment (clay, silt, sand, gravel, boulders) transported by a glacier and deposited directly by or from the ice, or by glacial meltwater. Drift is often subdivided into (unsorted and) unstratified drift (gla ...

covers bedrock over a large part of it. The Pleistocene ended with a gradual stagnation and a wasting of the ice in place. As a consequence, on many slopes a series of channels was formed at successive levels as ice surfaces wasted.

References

{{Plateaus and Highlands of British Columbia , state= expanded Interior Plateau Thompson Country Nicola Country Similkameen Country Geography of the Okanagan