HOME

TheInfoList



OR:

The Snake_River_cutting_through_the_plain_leaves_many_canyons_and_Canyon#List_of_gorges.html" ;"title="canyons.html" ;"title="Snake River cutting through the plain leaves many canyons">Snake River cutting through the plain leaves many canyons and Canyon#List of gorges">gorges, such as this one near Twin Falls, Idaho The Snake River Plain is a geologic feature located primarily within the U.S. state of
Idaho Idaho ( ) is a U.S. state, state in the Pacific Northwest region of the Western United States. To the north, it shares a small portion of the Canada–United States border with the province of British Columbia. It borders the states of Monta ...
. It stretches about westward from northwest of the state of
Wyoming Wyoming () is a state in the Mountain West subregion of the Western United States. It is bordered by Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho to the west, Utah to the southwest, and Colorado to t ...
to the Idaho-
Oregon Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...
border. The plain is a wide, flat bow-shaped depression and covers about a quarter of Idaho. Three major volcanic
butte __NOTOC__ In geomorphology, a butte () is an isolated hill with steep, often vertical sides and a small, relatively flat top; buttes are smaller landforms than mesas, plateaus, and tablelands. The word ''butte'' comes from a French word me ...
s dot the plain east of Arco, the largest being Big Southern Butte. Most of Idaho's major cities are in the Snake River Plain, as is much of its agricultural land.


Geology

The Snake River Plain can be divided into three sections: western, central, and eastern. The western Snake River Plain is a large tectonic
graben In geology, a graben () is a depressed block of the crust of a planet or moon, bordered by parallel normal faults. Etymology ''Graben'' is a loan word from German, meaning 'ditch' or 'trench'. The word was first used in the geologic conte ...
or rift valley filled with several kilometers of lacustrine (lake) sediments; the sediments are underlain by rhyolite and
basalt Basalt (; ) is an aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the surface of a rocky planet or moon. More than 90 ...
, and overlain by basalt. The western plain began to form around 11–12 Ma (million years ago) with the eruption of rhyolite lavas and ignimbrites. The western plain is not parallel to
North American Plate The North American Plate is a tectonic plate covering most of North America, Cuba, the Bahamas, extreme northeastern Asia, and parts of Iceland and the Azores. With an area of , it is the Earth's second largest tectonic plate, behind the Paci ...
motion and lies at a high angle to the central and eastern Snake River Plains. Its morphology is similar to other
volcanic plateau A volcanic plateau is a plateau produced by volcanic activity. There are two main types: lava plateaus and pyroclastic plateaus. Lava plateau Lava plateaus are formed by highly fluid basaltic lava during numerous successive eruptions thro ...
s such as the
Chilcotin Group The Chilcotin Group, also called the Chilcotin Plateau Basalts, is a large area of basaltic lava that forms a volcanic plateau running parallel with the Garibaldi Volcanic Belt in south-central British Columbia, Canada. Predominantly, during Mio ...
in south-central
British Columbia British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, for ...
, Canada. The eastern Snake River Plain traces the path of the North American Plate over the Yellowstone hotspot, now centered in
Yellowstone National Park Yellowstone National Park is an American national park located in the western United States, largely in the northwest corner of Wyoming and extending into Montana and Idaho. It was established by the 42nd U.S. Congress with the Yellowst ...
. The eastern plain is a topographic depression that cuts across Basin and Range mountain structures, more or less parallel to North American Plate motion. It is underlain almost entirely by basalt erupted from large shield volcanoes. Beneath the basalts are rhyolite lavas and ignimbrites that erupted as the lithosphere passed over the hotspot. The central Snake River plain is similar to the eastern plain but differs by having thick sections of
interbedded In geology, interbedding occurs when beds (layers of rock) of a particular lithology lie between or alternate with beds of a different lithology. For example, sedimentary rocks may be interbedded if there were sea level variations in their sedi ...
lacustrine (lake) and fluvial (stream) sediments, including the Hagerman fossil beds. Island Park and Yellowstone Calderas formed as the result of enormous rhyolite ignimbrite eruptions, with single eruptions producing up to of ash. Henry's Fork Caldera, measuring by , may be the largest symmetrical
caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is ...
in the world. The caldera formed when a dome of magma built up and then drained away. The center of the dome collapsed, leaving a caldera. Henry's Fork Caldera lies within the older and larger Island Park Caldera, which is by . Younger volcanoes that erupted after passing over the hotspot covered the plain with young basalt lava flows in places, including Craters of the Moon National Monument.


Effects on climate

The Snake River Plain has a significant effect on the climate of
Yellowstone National Park Yellowstone National Park is an American national park located in the western United States, largely in the northwest corner of Wyoming and extending into Montana and Idaho. It was established by the 42nd U.S. Congress with the Yellowst ...
and the adjacent areas to the south and west of Yellowstone. Over time, the Yellowstone hotspot left a wide channel through the
Rocky Mountains The Rocky Mountains, also known as the Rockies, are a major mountain range and the largest mountain system in North America. The Rocky Mountains stretch in straight-line distance from the northernmost part of western Canada, to New Mexico ...
. This channel is in line with the gap between the Cascade Range and the
Sierra Nevada The Sierra Nevada () is a mountain range in the Western United States, between the Central Valley of California and the Great Basin. The vast majority of the range lies in the state of California, although the Carson Range spur lies primar ...
. The result is a moisture channel extending from the Pacific Ocean to Yellowstone. Moisture from the Pacific Ocean streams onshore in the form of clouds and humid air. It passes through the gap between the Sierra and Cascades and into the Snake River Plain where it is channeled through most of the Rocky Mountains with no high plateaus or mountain ranges to impede its progress. It finally encounters upslope conditions at the head of the Snake River Valley at
Ashton, Idaho Ashton is a city in Fremont County, Idaho, United States. The population was 1,127 at the 2010 census, and it is part of the Rexburg Micropolitan Statistical Area. The district is noted for seed potato production and bills itself as the world's ...
; at
Island Park, Idaho Island Park is a city in Fremont County, Idaho, United States. The city's population was 286 at the 2010 census, up from 215 in 2000. The city was incorporated by owners of the many lodges and resorts along U.S. Route 20 in 1947, primarily to c ...
; at the Teton Range east of Driggs, Idaho; and at the Yellowstone Plateau of Yellowstone National Park where the channeled moisture precipitates out as rain and snow. The result is a localized climate on the eastern side of the Rockies that is akin to a climate on the west slope of the Cascades or the northern Sierra. The head of the Snake River Valley, the Tetons, and the Yellowstone Plateau receive much more precipitation than other areas of the region, and the area is known for being wet, green, having many streams, and having abundant snow in winter. Although the topography of the Plain has largely gone unchanged for several million years, this region's climate has not been so constant. Current climatic conditions began to characterize the region in the early Pleistocene (approximately 2.5 million years ago). However, the arid climate of today was born from the gradual dissipation of a climate defined by greater moisture and narrower ranges of annual temperatures.


See also

*
Lost streams of Idaho There are two rivers in Idaho named "Lost", the Big Lost River and the Little Lost River. They are often considered separate streams, but both flow into the same depression and become subterranean, feeding the Snake River Aquifer. The rivers ar ...
* Snake River * Snake River Plain (ecoregion) *
Wilson Butte Cave Wilson Butte Cave is located on the Snake River plain in Jerome County northeast of Twin Falls and southeast of Shoshone, Idaho. Listed on the National Register of Historic Places as an archeological site, it is maintained by the Bureau of La ...


References


External links


The Snake River Plain
at Digital Atlas of Idaho {{Authority control Landforms of Idaho Snake River Plains of the United States Rifts and grabens Valleys of Idaho Volcanism of Idaho Holocene volcanism Miocene volcanism Pleistocene volcanism Pliocene volcanism Natural history of Idaho Regions of the Western United States Holocene North America Miocene North America Pliocene North America Pleistocene United States Neogene Idaho Quaternary United States Landforms of Bonneville County, Idaho Landforms of Madison County, Idaho Landforms of Power County, Idaho Landforms of Twin Falls County, Idaho Landforms of Ada County, Idaho Landforms of Owyhee County, Idaho Landforms of Nez Perce County, Idaho Landforms of Bingham County, Idaho Landforms of Fremont County, Idaho Landforms of Elmore County, Idaho Landforms of Payette County, Idaho Landforms of Latah County, Idaho Landforms of Gooding County, Idaho Landforms of Canyon County, Idaho Landforms of Washington County, Idaho Landforms of Adams County, Idaho Landforms of Idaho County, Idaho