Kittitas County
Kittitas County () is a county located in the U.S. state of Washington. At the 2020 census, its population was 44,337. Its county seat and largest city is Ellensburg. The county was created in November 1883 when it was carved out of Yakima Coun ...
of
Washington
Washington commonly refers to:
* Washington (state), United States
* Washington, D.C., the capital of the United States
** A metonym for the federal government of the United States
** Washington metropolitan area, the metropolitan area centered o ...
state. It is set within the
Alpine Lakes Wilderness
The Alpine Lakes Wilderness is a large National Wilderness Preservation System, wilderness area spanning the Central Cascades of Washington (state), Washington state in the United States. The wilderness is located in parts of Wenatchee National F ...
which is part of the
Cascade Range
The Cascade Range or Cascades is a major mountain range of western North America, extending from southern British Columbia through Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as the North Cascades, ...
. Alta Mountain is situated on land managed by
Wenatchee National Forest
Wenatchee National Forest is a U.S. National Forest located in Washington. With an area of 1,735,394 acres (2,711.55 sq mi, or 7,022.89 km²), it extends about 137 miles along the eastern slopes of the Cascade Range of Washington, USA from ...
. Precipitation
runoff
Runoff, run-off or RUNOFF may refer to:
* RUNOFF, the first computer text-formatting program
* Runoff or run-off, another name for bleed, printing that lies beyond the edges to which a printed sheet is trimmed
* Runoff or run-off, a stock market ...
from the mountain drains into tributaries of the
Yakima River
The Yakima River is a tributary of the Columbia River in south central and eastern Washington state, named for the indigenous Yakama people. Lewis and Clark mention in their journals that the Chin-nâm pam (or the Lower Snake River Chamnapam Nat ...
.
Climate
Alta Mountain is located in the
marine west coast
An oceanic climate, also known as a marine climate, is the humid temperate climate sub-type in Köppen classification ''Cfb'', typical of west coasts in higher middle latitudes of continents, generally featuring cool summers and mild winters ( ...
climate zone of western North America.Beckey, Fred W. Cascade Alpine Guide, Climbing and High Routes. Seattle, WA: Mountaineers Books, 2008.
Weather front
A weather front is a boundary separating air masses for which several characteristics differ, such as air density, wind, temperature, and humidity. Disturbed and unstable weather due to these differences often arises along the boundary. For in ...
s originating in the Pacific Ocean travel northeast toward the
Cascade Mountains
The Cascade Range or Cascades is a major mountain range of western North America, extending from southern British Columbia through Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as the North Cascades, ...
. 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 snow onto the Cascades (
Orographic lift
Orographic lift occurs when an air mass is forced from a low elevation to a higher elevation as it moves over rising terrain. As the air mass gains altitude it quickly cools down adiabatically, which can raise the relative humidity to 100% and cr ...
). As a result, the west side of the Cascades experiences high precipitation, especially during the winter months in the form of snowfall. Because of maritime influence, snow tends to be wet and heavy, resulting in high
avalanche
An avalanche is a rapid flow of snow down a slope, such as a hill or mountain.
Avalanches can be set off spontaneously, by such factors as increased precipitation or snowpack weakening, or by external means such as humans, animals, and earth ...
danger. 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. The months of July through September offer the most favorable weather for viewing or climbing this peak.
Geology
The Alpine Lakes Wilderness features some of the most rugged topography in the
Cascade Range
The Cascade Range or Cascades is a major mountain range of western North America, extending from southern British Columbia through Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as the North Cascades, ...
with craggy peaks and ridges, deep
glacial valley
U-shaped valleys, also called trough valleys or glacial troughs, are formed by the process of glaciation. They are characteristic of mountain glaciation in particular. They have a characteristic U shape in cross-section, with steep, straight s ...
s, and
granite
Granite () is a coarse-grained (phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies undergro ...
walls spotted with over 700 mountain lakes. Geological events occurring many years ago created the diverse topography and drastic elevation changes over the Cascade Range leading to the various climate differences. These climate differences lead to vegetation variety defining the
ecoregion
An ecoregion (ecological region) or ecozone (ecological zone) is an ecologically and geographically defined area that is smaller than a bioregion, which in turn is smaller than a biogeographic realm. Ecoregions cover relatively large areas of l ...
s in this area.
The history of the formation of the Cascade Mountains dates back millions of years ago to the late
Eocene
The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...
Epoch. With the
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 Pacific ...
overriding the
Pacific Plate
The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At , it is the largest tectonic plate.
The plate first came into existence 190 million years ago, at the triple junction between the Farallon, Phoenix, and Iza ...
oceanic
Oceanic may refer to:
*Of or relating to the ocean
*Of or relating to Oceania
**Oceanic climate
**Oceanic languages
**Oceanic person or people, also called "Pacific Islander(s)"
Places
* Oceanic, British Columbia, a settlement on Smith Island, ...
and
continental lithosphere
A lithosphere () is the rigid, outermost rocky shell of a terrestrial planet or natural satellite. On Earth, it is composed of the crust and the portion of the upper mantle that behaves elastically on time scales of up to thousands of years o ...
called
terrane
In geology, a terrane (; in full, a tectonostratigraphic terrane) is a crust fragment formed on a tectonic plate (or broken off from it) and accreted or " sutured" to crust lying on another plate. The crustal block or fragment preserves its own ...
s created the
North Cascades
The North Cascades are a section of the Cascade Range of western North America. They span the border between the Canadian province of British Columbia and the U.S. state of Washington and are officially named in the U.S. and Canada as the Cascad ...
about 50 million years ago.
During the
Pleistocene
The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...
period dating back over two million years ago, glaciation advancing and retreating repeatedly scoured the landscape leaving deposits of rock debris. The last glacial retreat in the Alpine Lakes area began about 14,000 years ago and was north of the Canada–US border by 10,000 years ago. The U-shaped cross section of the river valleys is a result of that recent glaciation.
Uplift
Uplift may refer to: Science
* Geologic uplift, a geological process
** Tectonic uplift, a geological process
* Stellar uplift, the theoretical prospect of moving a stellar mass
* Uplift mountains
* Llano Uplift
* Nemaha Uplift
Business
* Uplif ...
and faulting in combination with glaciation have been the dominant processes which have created the tall peaks and deep valleys of the Alpine Lakes Wilderness area.
See also
*
*
Geography of Washington (state)
Washington is the northwesternmost state of the contiguous United States. It borders Idaho to the east, bounded mostly by the meridian running north from the confluence of the Snake River and Clearwater River (about 117°02'23" west), except f ...
*
Geology of the Pacific Northwest
The geology of the Pacific Northwest includes the composition (including rock, minerals, and soils), structure, physical properties and the processes that shape the Pacific Northwest region of North America. The region is part of the Ring of Fir ...
File:Rampart Lakes and Alta Mountain.jpg, Alta Mountain and Rampart Lakes
File:Alta Mountain west aspect.jpg, West aspect, from
Kendall Katwalk
Kendall Katwalk is a 150 yard long narrow pathway blasted out of a steeply sloped granite rock face on the north ridge of Kendall Peak approximately 6 miles northeast of Snoqualmie Pass. It is a segment of Section J of Pacific Crest Trail and th ...
File:Alta Mountain from the north.jpg, Alta Mountain from the north