 The Anahim hotspot has a long history . About 13 and 12 million years ago , the Anahim hotspot created a peralkaline volcanic complex on what was then the coast of British Columbia , now heavily eroded to form the ~ 20 km ( 12 mi ) long Bella Bella and ~ 6 km ( 4 mi ) long Gale Passage dike swarms . Individual dikes are as thick as 20 m ( 66 ft ) and have basalt , trachyte , and comendite compositions . The converging dikes may mark the first appearance of the Anahim hotspot . During the early to middle Miocene era , the passage of the Anahim hotspot beneath the range created the central Coast Mountains ; this orogeny caused reactions with the North American Plate in late Miocene @-@ Pliocene time . 
