Tuya

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A tuya is a flat-topped, steep-sided volcano, which has been built up on the surface of a plateau. Tuyas consist of nearly horizontal beds of basaltic lava capping outward-dipping beds of fragmental volcanic rocks.

S. Holland, a geographer for the British Columbia government, describes tuyas in the following way: "they have a most interesting origin...[they were] formed by volcanic eruptions which had been thawed through the Pleistocene ice-sheet by underlying volcanic heat. The lavas capping the mountains were extruded after the volcanoes were built above lake-level, and the outward-dipping beds were formed by the chilling of the lava when it reached the water's edge."

The origin of the term comes from Tuya Butte, one of many tuyas in the area of the Tuya River and Tuya Range in far northern British Columbia. Tuya Butte was the first such landform analyzed and so its name has entered the geological literature for this kind of volcanic formation. The Tuya Mountains Provincial Park was recently established to protect this unusual landscape, which lies north of Tuya Lake and south of the Jennings River near the boundary with the Yukon Territory.