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 Co ...

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

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 tota ...

, lying to the west of

Okanagan Lake Okanagan Lake ( oka, kɬúsx̌nítkw) is a lake in the Okanagan Valley of British Columbia, Canada. The lake is long, between wide, and has a surface area of 348 km2 (135 sq. mi.). Hydrography Okanagan Lake is called a fjord lake as ...

, 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 river ...

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 annua ...

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

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 ...

, and a series of passes from the area of Tulameen, British Columbia to the confluence of the

with the Nicoamen River, 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 th ...

, 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 near ...

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, ...

. 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, t ...

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 ani ...

, 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 tumb ...

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

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

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

Okanagan River The Okanogan River (known as the Okanagan River in Canada) is a tributary of the Columbia River, approximately 115 mi (185 km) long, in southern British Columbia and north central Washington. It drains a scenic plateau region called ...

History

The Thompson Plateau contains Nicola Athapaskan,

Nlaka'pamux The Nlaka'pamux or Nlakapamuk ( ; ), also previously known as the ''Thompson'', ''Thompson River Salish'', ''Thompson Salish'', ''Thompson River Indians'' or ''Thompson River people'', and historically as the ''Klackarpun'', ''Haukamaugh'', ''Kni ...

and Syilx 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 continen ...

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 Pacifi ...

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 Creta ...

. These rocks were pervasively intruded by magmas now forming

granitic A granitoid is a generic term for a diverse category of coarse-grained igneous rocks that consist predominantly of quartz, plagioclase, and alkali feldspar. Granitoids range from plagioclase-rich tonalites to alkali-rich syenites and from quart ...

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 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 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 finally confirmed ...

glaciation, and a thick mantle of glacial drift 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