Paoha Island
Encyclopedia
Paoha Island is a volcanic island
in Mono Lake
, an endorheic
lake in the U.S. state of California
. Formed by a series of eruptions in the 17th century, Paoha is composed of lakebed sediments deposited above volcanic domes. It is one of two major islands in the lake, the other being the smaller Negit Island
. Its name comes from a Native American word, Pa-o-ha, describing the abundant hot spring
s and fumarole
s on its surface.
The volcanic origin of the island gave rise to many vents, hot springs, fumaroles and mudpots on the surface of the island. An eruption sometime before the twentieth century created a crater lake
that is said to be shaped like a heart. Paoha Island is the younger of the two Mono Lake islands; Negit rose about 1,350 years before Paoha.
Paoha Island was named by Israel Cook Russell, a well-known American geologist, in the late 19th century. It supposedly received its name from the Paiute
word, pa-o-ha, for spirits they believed to exist in Paoha Island's hot springs. These spirits, or elves, were described as "diminutive sprites having long, waving hair, that were sometimes seen in the vapor-wreaths escaping from the hot springs."
The surface sediments of Paoha Island consist primarily of clay
and marl
, which are responsible for the pale surface. Volcanic ash
is scattered all around the island and basalt
is exposed at some of the lower elevations. There are also river-deposited sediments and granite
rocks.
.
The island is more mountainous near the east side, with the highest volcanic domes rising more or less than 200 feet (61 m) above the lake surface. The highest cone, which contains the heart-shaped crater lake, is located at the far northeastern end of the island. Several small islets are located off the island's west and south shores.
Island
An island or isle is any piece of sub-continental land that is surrounded by water. Very small islands such as emergent land features on atolls can be called islets, cays or keys. An island in a river or lake may be called an eyot , or holm...
in Mono Lake
Mono Lake
Mono Lake is a large, shallow saline lake in Mono County, California, formed at least 760,000 years ago as a terminal lake in a basin that has no outlet to the ocean...
, an endorheic
Endorheic
An endorheic basin is a closed drainage basin that retains water and allows no outflow to other bodies of water such as rivers or oceans...
lake in the U.S. state of California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
. Formed by a series of eruptions in the 17th century, Paoha is composed of lakebed sediments deposited above volcanic domes. It is one of two major islands in the lake, the other being the smaller Negit Island
Negit Island
Negit Island is an island in Mono Lake. Negit is a volcanic cone less than 2000 years old. It can be considered to be the northernmost of the Mono Craters. Negit is composed of three dark dacite lava flows....
. Its name comes from a Native American word, Pa-o-ha, describing the abundant hot spring
Hot spring
A hot spring is a spring that is produced by the emergence of geothermally heated groundwater from the Earth's crust. There are geothermal hot springs in many locations all over the crust of the earth.-Definitions:...
s and fumarole
Fumarole
A fumarole is an opening in a planet's crust, often in the neighborhood of volcanoes, which emits steam and gases such as carbon dioxide, sulfur dioxide, hydrochloric acid, and hydrogen sulfide. The steam is created when superheated water turns to steam as its pressure drops when it emerges from...
s on its surface.
History and geology
Only about 350 years ago, before the mid-17th century, the present-day Paoha Island did not exist. Volcanic eruptions on the lakebed gave rise to the island, which eventually rose to 6670 feet (2,033 m) above sea level, 290 feet (88.4 m) above the present-day elevation of Mono Lake. The pale color of the island is attributed to lakebed sediments rising above the lake surface along with the volcanic material.The volcanic origin of the island gave rise to many vents, hot springs, fumaroles and mudpots on the surface of the island. An eruption sometime before the twentieth century created a crater lake
Crater lake
A crater lake is a lake that forms in a volcanic crater or caldera, such as a maar; less commonly and with lower association to the term a lake may form in an impact crater caused by a meteorite. Sometimes lakes which form inside calderas are called caldera lakes, but often this distinction is not...
that is said to be shaped like a heart. Paoha Island is the younger of the two Mono Lake islands; Negit rose about 1,350 years before Paoha.
Paoha Island was named by Israel Cook Russell, a well-known American geologist, in the late 19th century. It supposedly received its name from the Paiute
Paiute
Paiute refers to three closely related groups of Native Americans — the Northern Paiute of California, Idaho, Nevada and Oregon; the Owens Valley Paiute of California and Nevada; and the Southern Paiute of Arizona, southeastern California and Nevada, and Utah.-Origin of name:The origin of...
word, pa-o-ha, for spirits they believed to exist in Paoha Island's hot springs. These spirits, or elves, were described as "diminutive sprites having long, waving hair, that were sometimes seen in the vapor-wreaths escaping from the hot springs."
The surface sediments of Paoha Island consist primarily of clay
Clay
Clay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...
and marl
Marl
Marl or marlstone is a calcium carbonate or lime-rich mud or mudstone which contains variable amounts of clays and aragonite. Marl was originally an old term loosely applied to a variety of materials, most of which occur as loose, earthy deposits consisting chiefly of an intimate mixture of clay...
, which are responsible for the pale surface. Volcanic ash
Volcanic ash
Volcanic ash consists of small tephra, which are bits of pulverized rock and glass created by volcanic eruptions, less than in diameter. There are three mechanisms of volcanic ash formation: gas release under decompression causing magmatic eruptions; thermal contraction from chilling on contact...
is scattered all around the island and basalt
Basalt
Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey...
is exposed at some of the lower elevations. There are also river-deposited sediments and granite
Granite
Granite is a common and widely occurring type of intrusive, felsic, igneous rock. Granite usually has a medium- to coarse-grained texture. Occasionally some individual crystals are larger than the groundmass, in which case the texture is known as porphyritic. A granitic rock with a porphyritic...
rocks.
Description
Paoha Island is located in the central part of Mono Lake, slightly closer to the western shore. It is a roughly oval-shaped landmass 2 miles (3.2 km) north-south and 1.5 miles (2.4 km) east-west. It is separated from Negit Island, to the north-northwest, by a narrow channel. During low water levels, Negit Island and eventually Paoha Island become connected to the mainland in one giant peninsulaPeninsula
A peninsula is a piece of land that is bordered by water on three sides but connected to mainland. In many Germanic and Celtic languages and also in Baltic, Slavic and Hungarian, peninsulas are called "half-islands"....
.
The island is more mountainous near the east side, with the highest volcanic domes rising more or less than 200 feet (61 m) above the lake surface. The highest cone, which contains the heart-shaped crater lake, is located at the far northeastern end of the island. Several small islets are located off the island's west and south shores.