page_title: Level Mountain
section_title: Volcanic history
hierarchical_section_title: Level Mountain / Geology / Volcanic history
caption_attribution_description: English: Geologic map of Level Mountain showing volcanic products and eruptive centres.
context_page_description: Level Mountain is a massive complex volcano in the Northern Interior of British Columbia, Canada. It is located 50 km north-northwest of Telegraph Creek and 60 km west of Dease Lake on the Nahlin Plateau. With a maximum elevation of 2,166 m, it is the third highest of five large complexes in an extensive north-south trending volcanic zone. Much of the mountain is gently-sloping; when measured from its base, Level Mountain is about 1,100 m tall, slightly taller than its neighbour to the northwest, Heart Peaks. The lower broader half of Level Mountain consists of a shield-like edifice while its upper half has a more steep, jagged profile. Its large summit is dominated by the Level Mountain Range, a small mountain range with prominent peaks cut by deep valleys. These valleys serve as a radial drainage for several small streams that flow from the volcano. Meszah Peak is the only named peak in the Level Mountain Range.
  The mountain began forming about 15 million years ago, with volcanism continuing up until geologically recent times. There have been four stages of activity throughout the long volcanic history of Level Mountain.
context_section_description: Level Mountain has experienced volcanic eruptions sporadically for the last 15 million years, making it the most persistent volcano of the NCVP. More than 20 eruptive centres are present on the summit and flanks of the complex. These have produced mainly felsic and mafic lavas, a chemical composition range typical of bimodal volcanism. Such volcanism commonly occurs at hotspots, continental rifts and leaky transform faults. The existence of olivine, orthopyroxene and spinel xenocrysts in Level Mountain basalt suggest that volcanism at the complex originated from the upper mantle. Hiatuses of up to a million years or more can be expected between periods of volcanic activity at Level Mountain.
  Like several other volcanoes in northern British Columbia, Level Mountain was volcanically active during past glacial periods. Its involvement with glaciation resulted in several interactions between magma and ice, affording multiple examples of glaciovolcanic processes. Evidence for contemporaneous volcanism and glaciation is widespread throughout the mountain. This includes interlayered unconsolidated fluvioglacial and tuffaceous deposits, tills and glacial erratics at the base of tuffs and lava flows, lahars composed of till and agglomerate, tuyas on the uppermost surface of the shield and as outliers, till cemented by siliceous sinter and the presence of freshwater pillow basalts and volcano-glacial tuff breccias. It is possible that geothermal outputs at Level Mountain had an influence on dynamics of past ice sheets much like the modern Grímsvötn caldera is an important heat source beneath Vatnajökull in Iceland. However, like other large NCVP volcanoes, much of Level Mountain was formed prior to glaciation.
  Initial volcanism of the NCVP 20 million years ago was sporadic, producing small volumes of material. The eruption rate increased markedly to around 0.0001 km³ (2.4×10⁻⁵ cu mi) per year when volcanism began at Level Mountain 14.9 million years ago as part of the shield-building stage. This stage of volcanism ended 6.9 million years ago with completion of the basal shield volcano. A second stage of volcanism occurred at Level Mountain between 7.1 and 5.3 million years ago to create the stratovolcano cap. The rate of volcanism in the NCVP during this stage of activity increased again to 0.0003 km³ (7.2×10⁻⁵ cu mi) per year. Dome-forming eruptions were dominant during the third eruptive stage 4.5 to 2.5 million years ago during which a magmatic lull appears to have been present throughout the NCVP. A fourth and final stage of volcanism at Level Mountain commenced  in the last 2.5 million years with the formation of minor volcanic cones and lava flows. The NCVP volcanism rate has since remained relatively constant at 0.0001 km³ (2.4×10⁻⁵ cu mi) per year with volcanism of the final stage having continued possibly in the last 10,000 years. Modern NCVP volcanism rates are much less than those estimated for Hawaii or the Cascade Volcanic Arc of western North America.
caption: Geologic map of Level Mountain showing eruptive products and eruptive centres
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