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Lava fields are large, mostly flat areas of surface or subaquatic
Lava fields are large, mostly flat areas of surface or subaquatic lava
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 un ...
flows. Such features are generally composed of highly fluid 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 ...
lava, and can extend for tens or hundreds of miles across the underlying terrain.
Morphology and structure
The final morphology of a lava field can reveal properties such as internal structure, composition, and mechanics of the lava flow when it was fluid. The ridges and patterns on top of the lava field show the direction of the channels and the oftentimes active lava tubes that may be underneath the solidified "crust." It can also reveal whether the lava flow can be classified aspāhoehoe
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 un ...
or 'a'ā
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 ...
. The two main types of lava field structures are defined as sheet flow lava and pillow lava
Pillow lavas are lavas that contain characteristic pillow-shaped structures that are attributed to the extrusion of the lava underwater, or ''subaqueous extrusion''. Pillow lavas in volcanic rock are characterized by thick sequences of disconti ...
. Sheet flow lava appears like a wrinkled or folded sheet, while pillow lava is bulbous, and often looks like a pile of pillows atop one another.
An important aspect of lava flow morphology is a phenomenon known as lava flow inflation. This occurs in pāhoehoe flows that have a high effusion rate, and initially forms a thin crust atop the lava flow. The fluid lava underneath the crust continues to increase due to the sustained high effusion rate, and thus the entire "structure" increases in size, up to four meters in height. This anomaly can expose important physics and mechanisms behind lava flow that was not previously known.
The structure of lava fields also vary based on geographic location. For example, in subaqueous lava fields, sheet flow lava is found near volcanoes characterized by fast-flowing centers, like the Galapagos Rift, while on the other hand pillow lava fields are found near more slow-flowing centers, like the Mid-Atlantic Ridge
The Mid-Atlantic Ridge is a mid-ocean ridge (a divergent or constructive plate boundary) located along the floor of the Atlantic Ocean, and part of the longest mountain range in the world. In the North Atlantic, the ridge separates the North Ame ...
.
Mapping and prediction
The extent of large lava fields is most readily studied from the air or insatellite
A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioisotope ...
photos, where their commonly dark, near black color contrasts sharply with the rest of the landscape. Current computer models are mostly unable to predict the placement of lava fields due to the inability to anticipate random environmental influences. Computer modelling is consistently increasing in quality, but the many micro factors directing lava flow and shape, such as source geometry and lava extrusion rate, limit the accuracy that is currently available.
Notable examples
*Boring Lava Field
The Boring Lava Field (also known as the Boring Volcanic Field) is a Plio-Pleistocene volcanic field with cinder cones, small shield volcanoes, and lava flows in the northern Willamette Valley of the U.S. state of Oregon and adjacent southwest ...
(United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
)
*Harrat Rahat
Ḥarrat Rahāṭ ( ar, حَرَّة رَهَاط) is a volcanic lava field in the Hejazi region of Saudi Arabia. In 1256 CE, a lava flow erupted from six aligned scoria cones, and traveled to within of the Holiest sites in Islam, Islamic holy ...
, which threatened the city of Medina
Medina,, ', "the radiant city"; or , ', (), "the city" officially Al Madinah Al Munawwarah (, , Turkish: Medine-i Münevvere) and also commonly simplified as Madīnah or Madinah (, ), is the Holiest sites in Islam, second-holiest city in Islam, ...
in the 13th century (Saudi Arabia
Saudi Arabia, officially the Kingdom of Saudi Arabia (KSA), is a country in Western Asia. It covers the bulk of the Arabian Peninsula, and has a land area of about , making it the fifth-largest country in Asia, the second-largest in the A ...
)
*Hell's Half Acre Lava Field
Hell's Half Acre Lava Field is a basaltic lava plain located on the Snake River Plain of Idaho in the United States. It is the easternmost of the basaltic lava fields on the Snake River Plain, located about west of Idaho Falls, Idaho and north ...
(Idaho
Idaho ( ) is a 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 Montana and Wyom ...
, United States)
*Reykjanes
Reykjanes () is a small headland on the southwestern tip of the Reykjanes Peninsula in Iceland, giving the main peninsula its name. The region is about from Iceland's international airport.
As the name means "smoking peninsula" connected to volc ...
, Iceland
Iceland ( is, Ísland; ) is a Nordic island country in the North Atlantic Ocean and in the Arctic Ocean. Iceland is the most sparsely populated country in Europe. Iceland's capital and largest city is Reykjavík, which (along with its s ...
(peninsula
A peninsula (; ) is a landform that extends from a mainland and is surrounded by water on most, but not all of its borders. A peninsula is also sometimes defined as a piece of land bordered by water on three of its sides. Peninsulas exist on all ...
is mainly a barren waste of lava fields)
*St. George
Saint George (Greek: Γεώργιος (Geórgios), Latin: Georgius, Arabic: القديس جرجس; died 23 April 303), also George of Lydda, was a Christian who is venerated as a saint in Christianity. According to tradition he was a soldier ...
, Utah
Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to it ...
, United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
(city built around fields and bluffs covered in lava rocks)
*Mackenzie Large Igneous Province
The Mackenzie Large Igneous Province (MLIP) is a major Mesoproterozoic large igneous province of the southwestern, western and northwestern Canadian Shield in Canada. It consists of a group of related igneous rocks that were formed during a massiv ...
, Canada
Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...
See also
*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 ...
*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 throu ...
*Volcanism of Hawaii
The Hawaii hotspot is a volcanic hotspot located near the namesake Hawaiian Islands, in the northern Pacific Ocean. One of the best known and intensively studied hotspots in the world, the Hawaii plume is responsible for the creation of the H ...
*Volcanism of Iceland :''The volcano system in Iceland that started activity on August 17, 2014, and ended on February 27, 2015, is Bárðarbunga.''
:''The volcano in Iceland that erupted in May 2011 is Grímsvötn.''
Iceland experiences frequent volcanic activity, d ...
*Volcano
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 ...
References