Burroughs Mountain

Burroughs Mountain, situated at the northeast foot of Mount Rainier, WA, exposes a large-volume (3.4 km3) andesitic lava flow, up to 350 m thick and extending 11 km in length. Two sampling traverses from flow base to eroded top, over vertical sections of 245 and 300 m, show that the flow consists of a felsic lower unit (100 m thick) overlain sharply by a more mafic upper unit. The mafic upper unit is chemically zoned, becoming slightly more evolved upward; the lower unit is heterogeneous and unzoned. The lower unit is also more phenocryst-rich and locally contains inclusions of quenched basaltic andesite magma that are absent from the upper unit. Widespread, gabbronorite-to-diorite inclusions may be fragments of shallow cumulates, exhumed from the Mount Rainier magmatic system.[3]

Burroughs Mountain is renowned for its accessible variety of alpine tundra plants including sedges (Cyperaceae), Saxifraga, Dwarf lupine (Lupinus lepidus), Luetkea, Antennaria, Koenigia davisiae, Alpine yellow fleabane (Erigeron aureus), Tundra Aster (Oreostemma alpigenum), Empetrum nigrum, Arenaria lateriflora, and more.

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  Dwarf Lupine (Lupinus lepidus)
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  Curved-beak lousewort (Pedicularis contorta)
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  Tundra Aster (Oreostemma alpigenum)
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  Polemonium elegans
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  Golden fleabane (Erigeron aureus)
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  Tolmie's saxifrage (Micranthes tolmiei)
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  Luetkea pectinata

Burroughs Mountain is habitat for the marmot, pika, mountain goat, and chipmunk. Deer and the American black bear (Ursus americanus) can be found lower on the mountain in Berkeley Park.

Burroughs Mountain is located in the marine west coast climate zone of western North America.[4] Most weather fronts originate in the Pacific Ocean, and travel northeast toward the Cascade Mountains. As fronts approach, they are forced upward by the peaks of the Cascade Range, causing them to drop their moisture in the form of rain or snowfall onto the Cascades. As a result, the west side of the North Cascades experiences high precipitation, especially during the winter months in the form of snowfall.[4] Due to its temperate climate and proximity to the Pacific Ocean, areas west of the Cascade Crest very rarely experience temperatures below 0 °F (−18 °C) or above 80 °F (27 °C).[4] During winter months, weather is usually cloudy, but, due to high pressure systems over the Pacific Ocean that intensify during summer months, there is often little or no cloud cover during the summer.[4] Because of maritime influence, snow tends to be wet and heavy, resulting in high avalanche danger.[4]