| Lava Beds National Monument | |
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IUCN Category III (Natural Monument)
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| Location | Siskiyou / Modoc counties, California, USA |
| Nearest city | Tulelake, California |
| Area | 46,560 acres (18,840 ha) |
| Established | 21 November 1925 |
| Visitors | 107,475 (in 2005) |
| Governing body | National Park Service |
Lava Beds National Monument is located in northeastern California, in Siskiyou and Modoc Counties. The Monument lies on the northeastern flank of the Medicine Lake Volcano, with the largest total area covered by a volcano in the Cascade Range.
The region in and around Lava Beds Monument is unique because it lies on the junction of the Sierra-Klamath, Cascade, and the Great Basin physiographic provinces. The Monument was established as a United States National Monument on November 21, 1925, including over 46,000 acres (190 km2).
Lava Beds National Monument has numerous Lava tube caves, with twenty five having marked entrances and developed trails for public access and exploration. The monument also offers trails through the high Great Basin xeric shrubland desert landscape and the volcanic fields.
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Lava Beds National Monument is geologically outstanding because of its great variety of "textbook" volcanic formations including: lava tube caves; fumaroles; cinder cones; spatter cones; pit craters; hornitos; maars; and lava flows and volcanic fields
Volcanic eruptions on the Medicine Lake Shield volcano have created an incredibly rugged landscape punctuated by these many landforms of volcanism.
Lava flows dated to about 30,000-40,000 years ago formed most of the lava tube caves in the monument. As the hot basaltic lava flowed downhill, the top cooled and crusted over, insulating the rest of the lava and forming lava tubes. Lavacicles on the ceiling of a lava tube were left as the level of lava in the tube retreated and the viscous lava on the ceiling dripped as it cooled.
Dripstone was created when lava splashed on the inside walls of the tubes. The leaching of minerals from pumice gravel, soils, and overlying rock provides for deposition of secondary speleothems in lava tubes.
Lava Beds National Monument has the largest concentration of lava tube caves in North America. One has electrical lighting, the others are illuminated by ceiling collapse portals or require flashlights, available to loan.
Roughly ninety percent of the lava in the Lava Beds Monument is basaltic. There are primarily two kinds of basaltic lava flows: pahoehoe and 'A'a. Pahoehoe is smooth and ropy and is the type most common in Lava Beds. Aa is formed when pahoehoe cools and loses some of its gases. Aa is rough, sharp, and jagged; an excellent example is the Devils Homestead lava flow, which originated at Fleener Chimneys. Most of the rest of the lava in the monument is andesitic. Pumice, a type of rhyolitic lava, also is found covering the monument; this rained down around 900 years ago during the eruption of Glass Mountain.
The flows from Mammoth and Modoc Craters comprise about 2/3 of the lava in the monument. 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 the: Callahan Flow; Schonchin Flow; Mammoth Crater Flow; Modoc Crater Flow; and Devils Homestead Flow.
Cinder cones are formed when magma is under great pressure. It is released in a fountain of lava, blown into the air from a central vent. The lava cools as it falls, forming cinders that pile up around the vent. When the pressure has been relieved, the rest of the lava flows from the base of the cone. Cinder cones typically only erupt once.
The cinder cones of Hippo Butte, Three Sisters, Juniper Butte, and Crescent Butte are all older than the Mammoth and Modoc Crater flows, more than 30,000-40,000 years old. Eagle Nest Butte and Bearpaw Butte are 114,000 years old. Schonchin Butte cinder cone and the andesitic flow from its base were formed around 62,000 years ago. The flow that formed Valentine Cave erupted 10,850 years ago. An eruption that formed The Castles is younger than the Mammoth Crater flows. Even younger were eruptions from Fleener Chimneys, such as the Devils Homestead flow, 10,500 years ago, and Black Crater 3,025 years ago. About 1,110 years ago, plus or minus 60 years, the Callahan flow was produced by an eruption from Cinder Butte. Though Cinder Butte is just outside the boundary of the monument, the Callahan flow is in Lava Beds and is the youngest flow in the monument.
Spatter cones are built out of thicker lava. The lava is thrown out of the vent and builds, layer by layer, a chimney surrounding the vent. Fleener Chimneys and Black Crater are examples of spatter cones.
Gillem Bluff, a fault scarp, was created as the region stretched and a block of earth dropped down along this fault (see Basin and Range Province). The tuff layer on top of Gillem Bluff is 2,000,000 years old, inferring the rock layers beneath are even older. The oldest lava flow from the Medicine Lake Volcano within the monument is the Basalt of Hovey Point, near Captain Jack's Stronghold, which is 450,000 years old. Petroglyph Point was created about 275,000 years ago when cinders erupted through the shallow water of Tule Lake; violent explosions of ash and steam formed layers upon layers of tuff.
The caldera itself is thought to have formed by subsidence, during which basalt and andesite were erupted up on the slopes.[1]
A series of small earthquakes in late 1988 has been attributed to subsidence in the caldera. N-NE trending ground cracks, as well as N-NE trending vent series show relationships between tectonism and volcanism. One very prevalent ground crack exists along the northeastern boundary of the monument- "The Big Crack."
The high elevation, semi-arid desert environment of Lava Beds Monument receives an average of 15 inches (380 mm) of annual precipitation. 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 (−8 °C) to 102 °F (39 °C). Average annual snowfall is 44 inches (110 cm).
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 purple Desert 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 which is 90–125 miles (140–201 km) west on the northern California coastline.
Despite harsh, semi-arid conditions, native wildlife has adapted to the environmental constraints present in the region. There are no terrestrial water resources in Lava Beds National Monument. Some animals obtain water from caves, while others fly about twenty km (12 miles) north to Tule Lake. Federal and state animal species of special concern in the Monument include: Cooper's Hawk (Accipiter cooperii), Fringed Myotis (Myotis thysanodes), Long-eared Myotis (Myotis evotic), Long-legged Myotis (Myotis volans), Pallid Bat (Antrozous pallidus), Silver-haired Bat (Lasionycteris noctivigans), Townsends Big-eared Bat (Corynorhinus townsendii), Western Small-footed Myotis (Myotis ciliolabrum), and American Badger (Taxidea taxus).
Because of a lack of surface water, amphibian presence in the monument is limited. The most common species found in the monument is the Pacific tree frog (Pseudacris regilla). This species is also found in the biologically rich cave entrances in the monument. Reptile species found in the monument include: northern sagebrush lizard (Sceloporus graciosus graciosus), Great Basin fence lizard (Sceloporus occidentalis biseriatus), western skink (Eumeces skiltonianus skiltonianus), Rocky Mountain rubber boa (Charina bottae utahensis), gopher snake (Pituophis melanoleucus), desert night snake (Hypsiglena torquata deserticola), western rattlesnake (Crotalus viridis).
Key animal species by habitat:
Lava Beds National Monument includes Petroglyph Point, one of the largest panels of Native American rock art in the United States. The region is the of the Modoc people. The Lava Beds National Monument Archeological District was listed on the National Register of Historic Places in March 1991.[2]
During the Modoc War of 1872-1873, the Modoc Indians used these tortuous lava flows of their homeland to defend their territory. Under the leadership of Native American 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, that numbered up to ten times the Modocs' population, for five months. Gen E. R. S. Canby was killed here in April 1873 by Captain Jack at a meeting attempting to negotiate peace terms.
The Lava Beds National Wilderness Area is a 28,460-acre (11,520 ha) wilderness area within the Lava Beds National Monument. It was designated by the US Congress on October 13, 1972 with passage of Public Law 92-493.[3] The wilderness protects more than half of the national monument in two separate eastern and western units. The larger eastern unit contains the extensive Schonchin lava flow on the east side of the monument. The western unit covers the monument's area within the transition zone of the Cascade Range's montaine southern end and the arid Modoc Plateau ecosystems.
The different soil types creates plant community diversity in the Wilderness Area, providing various habitats for a wide range of wildlife. The numerous coyotes and foxes, as well as raptors feed on rodents such as the jackrabbit and kangaroo rat. The kangaroo rat here is especially adapted to dry, waterless environments because it can go 'a lifetime' without water.[4] A metabolic process occurs where water is synthesized from chemical components in the dry seeds that the rat eats.[4]
Many of the birds seen the Wilderness Area are raptors, with 24 species of hawks identified.[5] The monument is located on the Pacific Flyway and the Bald eagle winters here in the northern portion of the Wilderness Area. The National Park Service manages the Lava Beds Wilderness Area and has several restrictions in place, such as camping prohibited near cave entrances or trails. Open campfires may be prohibited during very hot and dry weather.
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