Espenberg is a

volcanic field A volcanic field is an area of Earth's crust that is prone to localized volcanic activity. The type and number of volcanoes required to be called a "field" is not well-defined. Volcanic fields usually consist of clusters of up to 100 volcanoes ...

Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S., ...

that contains the largest

maar A maar is a broad, low-relief volcanic crater caused by a phreatomagmatic eruption (an explosion which occurs when groundwater comes into contact with hot lava or magma). A maar characteristically fills with water to form a relatively shallow ...

s on

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

. It was active 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 ...

until 17,500 years BP, when a large eruption formed the wide Devil Mountain Maar and deposited

tephra Tephra is fragmental material produced by a volcanic eruption regardless of composition, fragment size, or emplacement mechanism. Volcanologists also refer to airborne fragments as pyroclasts. Once clasts have fallen to the ground, they rem ...

over , burying vegetation and forming the largest maar on Earth. Other maars in the field are the North and South Killeak Maars and Whitefish Maar, and

Devil Mountain Devil Mountain, sometimes mistakenly called Devil's Mountain, is a wooded mountain in the Municipality of Temagami, Northeastern Ontario, Canada. It overlies Devil Island in Lake Temagami with an elevation of above sea level. A short trail from ...

is a

shield volcano A shield volcano is a type of volcano named for its low profile, resembling a warrior's shield lying on the ground. It is formed by the eruption of highly fluid (low viscosity) lava, which travels farther and forms thinner flows than the more v ...

. The large size of these maars has been attributed to the interaction between

permafrost Permafrost is ground that continuously remains below 0 °C (32 °F) for two or more years, located on land or under the ocean. Most common in the Northern Hemisphere, around 15% of the Northern Hemisphere or 11% of the global surface ...

and ascending

magma Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natural sa ...

, which favoured intense

explosive eruption In volcanology, an explosive eruption is a volcanic eruption of the most violent type. A notable example is the 1980 eruption of Mount St. Helens. Such eruptions result when sufficient gas has dissolved under pressure within a viscous magma such ...

s. Soils buried underneath the Devil Mountain Maar tephra have been used to reconstruct the regional climate during the

last glacial maximum The Last Glacial Maximum (LGM), also referred to as the Late Glacial Maximum, was the most recent time during the Last Glacial Period that ice sheets were at their greatest extent. Ice sheets covered much of Northern North America, Northern Eur ...

. The maars are part of the Bering Land Bridge National Preserve.

Toponyms

"Killeak" means "East" in the Inupiaq language. Devil Mountain Maar is also known as "Qitiqliik" or "Kitakhleek" ("Double Lakes") and Whitefish Maar as "Narvaaruaq" or "Navaruk" ("Big Lake"). This volcanic field is also known as the Cape Espenberg-Devil Mountain volcanic field.

Geography and geomorphology

The Espenberg volcanoes lie on the northern

Seward Peninsula The Seward Peninsula is a large peninsula on the western coast of the U.S. state of Alaska whose westernmost point is Cape Prince of Wales. The peninsula projects about into the Bering Sea between Norton Sound, the Bering Strait, the Chukchi S ...

. They are the northernmost volcanoes of

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

with late

activity, lying just south of the

Arctic Circle The Arctic Circle is one of the two polar circles, and the most northerly of the five major circles of latitude as shown on maps of Earth. Its southern equivalent is the Antarctic Circle. The Arctic Circle marks the southernmost latitude at w ...

. Other volcanoes of the Seward Peninsula are found at

Imuruk Lake Imuruk Lake is the largest body of fresh water in Seward Peninsula in the U.S. state of Alaska. It measures and has a drainage basin of , It lies on top of a lava plateau at an elevation of . The drainage basin is relatively flat, as the maxim ...

. There are no roads in the area but the maars can be readily reached from the sea by following streams or by chartered

bush aircraft A bush airplane is a general aviation aircraft used to provide both scheduled and unscheduled passenger and flight services to remote, undeveloped areas, such as the Canadian north or bush, Alaskan tundra, the African bush, or savanna, Amazon rai ...

. Espenberg is located on a peninsula between the

Chukchi Sea Chukchi Sea ( rus, Чуко́тское мо́ре, r=Chukotskoye more, p=tɕʊˈkotskəjə ˈmorʲɪ), sometimes referred to as the Chuuk Sea, Chukotsk Sea or the Sea of Chukotsk, is a marginal sea of the Arctic Ocean. It is bounded on the west b ...

to the north and west and

Goodhope Bay Goodhope Bay is a small bay in the Kotzebue Sound, on the Chukchi Sea-facing coast of Alaska. It is across. It is located on the northern coast of the Seward Peninsula, 30 mi. W of Deering; Kotzebue-Kobuk Low . Lieutenant Otto von Kotzebue ...

to the east. From east to west lie North and South Killeak Maar, Devil Mountain Maar and Whitefish Maar; additionally there are

cinder cone A cinder cone (or scoria cone) is a steep conical hill of loose pyroclastic fragments, such as volcanic clinkers, volcanic ash, or scoria that has been built around a volcanic vent. The pyroclastic fragments are formed by explosive eruptions o ...

lava flow Lava is molten or partially molten rock (magma) that has been expelled from the interior of a terrestrial planet (such as Earth) or a moon onto its surface. Lava may be erupted at a volcano or through a fracture in the crust, on land or und ...

s and five small shield-like volcanoes such as Devil Mountain. Devil Mountain appears to be capped with an alignment of cinder cones with associated lava flows. Volcanologically, the field is situated in a

back-arc A back-arc basin is a type of geologic basin, found at some convergent plate boundaries. Presently all back-arc basins are submarine features associated with island arcs and subduction zones, with many found in the western Pacific Ocean. Most o ...

region. Volcanic rocks from the field have

basalt Basalt (; ) is an aphanite, 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 planetary surface, surface of a terrestrial ...

ic compositions. Devil Mountain Maar is wide and deep, while North Killeak Maar, South Killeak Maar and Whitefish Maar are , and wide and the Killeak Maars reach depths of over ; Whitefish Maar is much shallower with a depth of . Such dimensions make the Espenberg maars the largest known on

and the Espenberg maars comparable in size with

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 ...

s; other maars at lower latitudes are much smaller. The maars are mostly circular with the exception of Devil Mountain Maar which is partly separated by a small

sand spit A spit or sandspit is a deposition bar or beach landform off coasts or lake shores. It develops in places where re-entrance occurs, such as at a cove's headlands, by the process of longshore drift by longshore currents. The drift occurs due t ...

into the northern wide North Devil Mountain Maar and the wide South Devil Mountain Maar; formerly they were considered to be two separate maars. The water surface of the maars lies between below their rim. Eight wide and deep crater-like depressions lie underwater in Devil Mountain Maar and similar but partly filled depressions are also found at the Killeak Maars. Layered volcanic deposits crop out in high

cliff In geography and geology, a cliff is an area of rock which has a general angle defined by the vertical, or nearly vertical. Cliffs are formed by the processes of weathering and erosion, with the effect of gravity. Cliffs are common on co ...

s around Devil Mountain Maar and within

gullies A gully is a landform created by running water, mass movement, or commonly a combination of both eroding sharply into soil or other relatively erodible material, typically on a hillside or in river floodplains or terraces. Gullies resemble lar ...

around the other maars. The maars are emplaced in over thick lavas and sediments of Pleistocene age. The Singeakpuk River, the Kalik River, the Kitluk River, the Espenberg River and the Kongachuk Creek flow through the volcanic field; the Kitluk River drains Devil Mountain Maar. Other than volcanic constructs, plateaus,

thermokarst lake Alas ( sah, Алаас) is a shallow depression which occurs primarily in Yakutia, which is formed by subsidence of the Arctic permafrost owing to repeated melting and refreezing. An alas first develops as a shallow lake as melt water fills the ...

s, dry lakes and

yedoma Yedoma (russian: едома) is an organic-rich (about 2% carbon by mass) Pleistocene-age permafrost with ice content of 50–90% by volume. Yedoma are abundant in the cold regions of eastern Siberia, such as northern Yakutia, as well as in Alas ...

hills dot the landscape.

Climate, biota and human use

Kotzebue Kotzebue ( ) or Qikiqtaġruk ( , ) is a city in the Northwest Arctic Borough in the U.S. state of Alaska. It is the borough's seat, by far its largest community and the economic and transportation hub of the subregion of Alaska encompassing t ...

, northeast of the volcanic field, annual temperatures fluctuate between in July and in January. Annual precipitation there is about , mostly falling during summer. The vegetation belongs to the

Bering tundra The Bering tundra ecoregion (WWF ID: PA1102) is an ecoregion that covers a portion of northeastern Russia, between the Kolyma Mountains on the west, and the Bering Sea coast to the east. The area is an important stopping place for migratory bird ...

ecoregion and is not uniform over the area.

Green alder ''Alnus alnobetula'' is a common tree widespread across much of Europe, Asia, and North America. Many sources refer to it as ''Alnus viridis'', the green alder, but botanically this is considered an illegitimate name synonymous with ''Alnus alno ...

thickets and

willow Willows, also called sallows and osiers, from the genus ''Salix'', comprise around 400 speciesMabberley, D.J. 1997. The Plant Book, Cambridge University Press #2: Cambridge. of typically deciduous trees and shrubs, found primarily on moist s ...

grow on the maar benches; at Tempest Lake north of Devil Mountain Maar the vegetation is characterized by a

tundra In physical geography, tundra () is a type of biome where tree growth is hindered by frigid temperatures and short growing seasons. The term ''tundra'' comes through Russian (') from the Kildin Sámi word (') meaning "uplands", "treeless moun ...

featuring

forbs A forb or phorb is an herbaceous flowering plant that is not a graminoid (grass, sedge, or rush). The term is used in biology and in vegetation ecology, especially in relation to grasslands and understory. Typically these are dicots without woo ...

moss Mosses are small, non-vascular flowerless plants in the taxonomic division Bryophyta (, ) '' sensu stricto''. Bryophyta (''sensu lato'', Schimp. 1879) may also refer to the parent group bryophytes, which comprise liverworts, mosses, and hor ...

es,

sedge The Cyperaceae are a family of graminoid (grass-like), monocotyledonous flowering plants known as sedges. The family is large, with some 5,500 known species described in about 90 genera, the largest being the "true sedges" genus ''Carex'' wit ...

s and

shrub A shrub (often also called a bush) is a small-to-medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees ...

s and is quite dense.

Caribou Reindeer (in North American English, known as caribou if wild and ''reindeer'' if domesticated) are deer in the genus ''Rangifer''. For the last few decades, reindeer were assigned to one species, ''Rangifer tarandus'', with about 10 subspe ...

used to be frequent in the area, and there are numerous fish in the maars. Native Americans used the maars as a source of fish and as hunting grounds, and remains of human activity have been identified at their shores. Devil Mountain was used as a lookout post, navigational landmark and as a source of rocks for sinkers and weights. In recent times,

sediment core A core sample is a cylindrical section of (usually) a naturally-occurring substance. Most core samples are obtained by drilling with special drills into the substance, such as sediment or rock, with a hollow steel tube, called a core drill. The ...

s were obtained from North Killeak Maar and Whitefish Maar; the former has been used to reconstruct the past climate of the region during the

Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togethe ...

, including the occurrence of cold periods. The Espenberg volcanoes are part of the Bering Land Bridge National Preserve.

Eruption history

The non-maar vents at Espenberg appear to be over 500,000 years old, given that they are covered with vegetation and the lavas shattered by frost, and are probably older than the maars. The Espenberg maars were originally considered to be of Holocene age, but research has shown that the latest eruptions occurred during the Pleistocene. Various dating methods have been used to determine the ages of the Espenberg maars: * Whitefish Maar might be 100,000 – 200,000 years old, perhaps 160,000 years ago. Sedimentation since the eruption has partly filled in Whitefish Maar and reduced its depth. * North Killeak Maar is over 125,000 years old, older than South Killeak Maar. * South Killeak Maar formed over 40,000 years ago. * Devil Mountain Maar is the youngest vent, it formed 17,500 years BP and is the most recent volcanic event of the area. Formerly it was believed that its northern half was 7,100 years old. All maars formed in one complex eruption sequence which in the case of Devil Mountain Maar probably lasted only a few weeks to months. During the eruption, numerous individual explosions and surges took place and emplaced

base surge A pyroclastic surge is a fluidised mass of turbulent gas and rock fragments that is ejected during some volcanic eruptions. It is similar to a pyroclastic flow but it has a lower density or contains a much higher ratio of gas to rock, which makes i ...

s and Strombolian deposits, while frozen blocks of sediment were ejected from the vents. Devil Mountain Maar appears to have formed from the coalescence of several vents during the course of the eruption. Individual explosive events formed the depressions on the floor of the maars. Devil Mountain Maar deposited a

called the Devil Mountain Lake tephra over an area of . It reached thickness of more than over an area of , burying soil and vegetation and falling into lakes. The soil found underneath the Devil Mountain Maar tephra is known as Kitluk paleosoil. Plant remains found buried underneath the tephra are well preserved and have been used to infer climatic and biotic conditions during the

in the region; vegetation at that time was apparently different from today and there was no widespread ice cover. The tephra is used as a tephrostratigraphic marker for the late Pleistocene. The eruption of the Killeak Maars also produced tephra deposits, which are also found in lakes and have similar compositions to the tephra of the Devil Mountain Maar. Their deposition disrupted local

wetland A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (anoxic) processes prevailing, especially in the soils. The ...

s and altered the topography.

Mechanism of formation

Maar A maar is a broad, low-relief volcanic crater caused by a phreatomagmatic eruption (an explosion which occurs when groundwater comes into contact with hot lava or magma). A maar characteristically fills with water to form a relatively shallow ...

s are after cinder cones the second-most common type of volcano. They form when

interacts explosively with surrounding rocks, excavating broad but shallow craters on the surface. The Espenberg maars are the first known maars to have formed within

; other large maars in permafrost have been found in the

Pali-Aike volcanic field The Pali-Aike volcanic field is a volcanic field along the Argentina–Chile border. It is part of a family of back-arc volcanoes in Patagonia, which formed from processes involving the collision of the Chile Ridge with the Peru–Chile Trench. ...

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

. Interactions between magma and ice are different than these between lava and ice, as ice conducts heat only slowly and a large amount of energy is consumed during its sublimation; thus its melting and explosive evaporation occurs only slowly. The maars lie in thick permafrost, which was probably thicker during the Pleistocene when the maars formed. The abundant ice would have produced a limited amount of water due to

thermodynamic Thermodynamics is a branch of physics that deals with heat, work, and temperature, and their relation to energy, entropy, and the physical properties of matter and radiation. The behavior of these quantities is governed by the four laws of ther ...

limitations of magma-induced ice melting, creating an ideal environment for highly

s which may have been further intensified by the release of

methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Eart ...

during the thawing of the permafrost.

Landslide Landslides, also known as landslips, are several forms of mass wasting that may include a wide range of ground movements, such as rockfalls, deep-seated grade (slope), slope failures, mudflows, and debris flows. Landslides occur in a variety of ...

s at the margins of the

volcanic vent A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates are ...

s expanded the forming craters and supplied additional ice to the evaporation processes, ultimately yielding the large size of the Espenberg maars. The eruptions that formed the Espenberg maars occurred during fully

glacial A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate betw ...

climate, while

interglacial An interglacial period (or alternatively interglacial, interglaciation) is a geological interval of warmer global average temperature lasting thousands of years that separates consecutive glacial periods within an ice age. The current Holocene in ...

(including Holocene) eruptions on the Seward Peninsula have yielded lava flows; this implies that the glacial climate influenced the types of eruption that took place. The Espenberg maars have been used as analogues for certain craters on

Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury (planet), Mercury. In the English language, Mars is named for the Mars (mythology), Roman god of war. Mars is a terr ...

References

Sources

* * * * * * * {{refend

External links

Environmental Histories from Whitefish and Imuruk Lakes, Seward Peninsula, Alaska
Back-arc basins Maars of Alaska Pleistocene volcanoes Volcanic fields Volcanoes of Alaska