Intermontane Belt

The Intermontane Belt is a physiogeological region in the Pacific Northwest of North America, stretching from northern Washington into British Columbia, Yukon, and Alaska.

[1] As the North American Plate drifted west and the Intermontane Plate drifted east to the ancient continental margin of western North America, the Slide Mountain Ocean eventually closed by ongoing subduction under the Slide Mountain Ocean.

[1] The subduction zone eventually jammed and shut down completely about 180 million years ago, ending the volcanic arc on the ancient continental margin of western North America and the Intermontane Islands collided, forming the Intermontane Belt.

[1] After the sedimentary and igneous rocks were folded and crushed, it resulted in the creation of a new continental shelf and coastline.

[1] Magma rising from the Omineca Arc successfully connected the Intermontane Belt to the mainland of North America, forming a chain of volcanoes from Washington to British Columbia that existed for about 60 million years.