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Lava Beds National Monument is a land of turmoil, both geological and
historical. Over the last half-million years, volcanic eruptions on the
Medicine Lake shield volcano created an incredibly rugged landscape punctuated
by cinder cones, lava flows, spatter cones, lava tube caves and pit craters.
These lava tube caves, of which there are more than 500 in the Monument,
are a favorite underground destination for visitors to explore.
During the Modoc War of 1872-1873, the Modoc Indians used these lava flows
to their advantage. Under the leadership of Captain Jack, the Modocs took
refuge in "Captain Jack's Stronghold," a natural lava fortress.
From this base a group of 53 fighting men and their families held off US
Army forces numbering up to ten times their strength for five months.
The historic battlegrounds of the Modoc War and the surrounding volcanic
landscape are the primary reasons the Lava Beds were designated as a National
Monument in 1925.
Lava Beds National Monument is the site of the largest concentration of
lava tube caves in the United States. The monument lies on the northeast
flank of the Medicine Lake shield volcano, the largest volcano (total
area covered) in the Cascade Range. The region in and around the monument
is unique because it lies on the junction of the Sierra-Klamath, Cascade,
and Great Basin physiographic provinces. In addition, the monument is
geologically outstanding because of its great variety of textbook volcanic
formations; i.e., lava tube caves, fumaroles, cinder cones, spatter cones,
maar volcanoes, and lava flows. Over 30 separate lava flows located in
the park range in age from 2,000,000 years BP to 1,110 years BP. Some
of the major Lava Flows within Lava Beds National Monument include: Callahan
Flow, Schonchin Flow, Mammoth Crater Flow, Modoc Crater Flow, and Devils
Homestead Flow. The high elevation, semi-arid desert environment of Lava
Beds receives an average of 15 inches (381mm) of precipitation annually.
The climate is characterized by warm, dry summers and cold winters. The
average annual high temperature is 60 F (16 C) and average annual low
temperature is 35 F (2 C). Temperature extremes range from 18 F ( -28
C) to 102 F (39 C). Average annual snowfall is 44 inches (1118 mm). The
lava tube collapse systems and lava outcrops support a great diversity
of plant life, from an impressive variety of lichens and mosses to plants
such as desert sweet (Chamaebatiaria millefolium) and the aromatic desert
(purple) sage (Salvia dorrii carnosa). An impressive variety of fern species
are present in cave entrances including the spreading wood fern (Dryopteris
expansa) and the western swordfern (Polystichum munitum). These species
are well outside of their normal range 90 - 125 miles away on the northern
California coastline.
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