The Cassiar Mountains are the most northerly group of the Northern Interior Mountains

Interior Mountains

The Interior Mountains, also called the Northern Interior Mountains and Interior Ranges, are the semi-official names for a huge area that comprises much of the northern two thirds of the Canadian province of British Columbia and a large area of southern Yukon...

 in the Canadian province of British Columbia

British Columbia

British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...

 and the Yukon Territory. They lie north and west of the Omineca Mountains

Omineca Mountains

The Omineca Mountains, also known as "the Ominecas", are a group of remote mountain ranges in north-central British Columbia, Canada. They are bounded by the Finlay River on the north, the Rocky Mountain Trench on the east, the Nation River on the south, and the upper reaches of the Omineca River...

, west of the northernmost Rockies and the Rocky Mountain Trench

Rocky Mountain Trench

The Rocky Mountain Trench, or the Trench or The Valley of a Thousand Peaks, is a large valley in the northern part of the Rocky Mountains. It is both visually and cartographically a striking physiographic feature extending approximately from Flathead Lake, Montana, to the Liard River, just south...

, north of the Hazelton Mountains

Hazelton Mountains

The Hazelton Mountains are a grouping of mountain ranges on the inland lee of the Kitimat Ranges of the Coast Mountains in northwestern British Columbia, Canada, spanning the area of Hazelton, British Columbia south to the Nechako Reservoir...

 and east of the Boundary Ranges

Boundary Ranges

The Boundary Ranges, also known in the singular and as the Alaska Boundary Range, are the largest and most northerly subrange of the Coast Mountains...

. Physiographically, they are a section of the larger Yukon-Tanana Uplands province, which in turn are part of the larger Intermontane Plateaus

Intermontane Plateaus

Physiographic regions of the U.S. InteriorSee:legendIn some places,high plateaus lie between the mountain ranges, for example,the plateau of Anatolia in Turkey and the plateau of Tibet.These are called "Intermontane plateaus"....

 physiographic division.

In the western Cassiar Mountains lie the remnants of a prehistoric shield volcano

Shield volcano

A shield volcano is a type of volcano usually built almost entirely of fluid lava flows. They are named for their large size and low profile, resembling a warrior's shield. This is caused by the highly fluid lava they erupt, which travels farther than lava erupted from more explosive volcanoes...

 called the Maitland Volcano

Maitland Volcano

Maitland Volcano was a Pliocene age shield volcano in the western Cassiar Mountains of northwestern British Columbia, Canada. In the course of one million years, Maitland Volcano was formed on a mature, eroded Tertiary surface by rifting of the North American continent as thin alkali olivine basalt...

 which formed between 5 and 4 million years ago during the Pliocene

Pliocene

The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...

 period.

The highest mountain in the Cassiar Mountains is Thudaka Peak

Thudaka Peak

Thudaka Peak is the highest mountain of the Thudaka Range of the Cassiar Mountains in the Northern Interior of British Columbia, Canada, located between the heads of Obo River and Frog River. Glaciers exist on Thudaka's northern flanks, but the zone is usually quite dry.-References:* in the...

, at 2748 m (9,016 ft).

Sub-ranges and major summits

• Dease Plateau
  Dease Plateau
  The Dease Plateau is a subregion of the larger Yukon Plateau, and is located in far northern British Columbia, Canada, northwest from the Deadwood River to and beyond the Yukon-British Columbia boundary. The plateau is named in association with Dease Lake and the Dease River...
  
  
  • Horseranch Range
    Horseranch Range
    The Horseranch Range is a long north-south trending mountain range in northern British Columbia, Canada, located at the head of the Red River to the northwest of Deadwood Lake. Part of the Dease Plateau of the Cassiar Mountains system, it contains no glaciers and lies completely above tree...
    
    
• Kechika Ranges
  Kechika Ranges
  The Kechika Ranges are a subrange of the Cassiar Mountains subdivision of the Interior Mountains in far northern British Columbia, Canada, lying west of the Rocky Mountain Trench between the Rainbow and Deadwood Rivers .-References:*...
  
  
• Sifton Ranges
  Sifton Ranges
  The Sifton Ranges are a mountain range along the west side of the Rocky Mountain Trench in northern British Columbia, Canada. It has an area of 1820 km2 and is a subrange of the Cassiar Mountains which in turn form part of the Interior Mountains....
  
  
  • Cormier Range
    Cormier Range
    The Cormier Range is a subrange of the Sifton Ranges, located between the Finlay River and Fox River in northern British Columbia, Canada. This northwest trending mountain range extends from Ware to Fox Pass.-References:...
    
    
  • Ruby Range
    Ruby Range (Sifton Ranges)
    The Ruby Range is a subrange of the Sifton Ranges, located west of Spinnel Creek and east of Obo River in northern British Columbia, Canada.-References:* in the Canadian Mountain Encyclopedia...
    
    
• Stikine Ranges
  Stikine Ranges
  The Stikine Ranges are a mountain range in northwestern British Columbia, Canada. They are the northernmost subdivision of the Cassiar Mountains and among the least explored and most undeveloped parts of the province.-Sub-ranges:*Beady Range...
  
  
  • Beady Range
    Beady Range
    The Beady Range is a subrange of the Stikine Ranges, located northeast of northern Dease Lake in northern British Columbia, Canada.-References:* in the Canadian Mountain Encyclopedia...
    
    
  • Nisutlin Plateau
    Nisutlin Plateau
    The Nisutlin Plateau is a plateau in northern British Columbia, Canada, extending from Teslin Lake to the Cassiar Mountains.-References:* in the Canadian Mountain Encyclopedia...
    
    
  • Skree Range
    Skree Range
    The Skree Range is a subrange of the Stikine Ranges, located between the Dease River and Eagle River in northern British Columbia, Canada.-References:* in the Canadian Mountain Encyclopedia...
    
    
  • Three Sisters Range
    Three Sisters Range
    The Three Sisters Range is a subrange of the Stikine Ranges, located northwest of junction of the Stikine and McBride Rivers in northern British Columbia, Canada and to the southeast of the community of Dease Lake.-References:...
    
    
  • Thudaka Range
    Thudaka Range
    The Thudaka Range is a mountain range located east of the Rocky Mountain Trench in British Columbia, Canada bounded by the Obo River on the east, the Frog River on the west, and on the south by the pass between Geese and Thudaka Creeks. The highest peak in the range is Thudaka Peak at . The range...
    
    
    • Thudaka Peak
      Thudaka Peak
      Thudaka Peak is the highest mountain of the Thudaka Range of the Cassiar Mountains in the Northern Interior of British Columbia, Canada, located between the heads of Obo River and Frog River. Glaciers exist on Thudaka's northern flanks, but the zone is usually quite dry.-References:* in the...
      
      
  • Tuya Range
    Tuya Range
    The Tuya Range is a range of tuyas, located in the Stikine Ranges of the Cassiar Mountains in the far northr of the Canadian province of British Columbia, near its border with the Yukon Territory and to the southwest of Watson Lake, Yukon, which is the nearest major settlement.-Boundaries and...
    
    
    • Ash Mountain
      Ash Mountain (British Columbia)
      Ash Mountain is the highest summit in the Tuya Range of the Stikine Ranges in northcentral British Columbia, Canada, located immediately north of High Tuya Lake at the north end of Tuya Mountains Provincial Park. It is one of the six tuyas clustered close to Tuya Lake...