Hesperia Planum is a broad

lava plain Lava fields are large, mostly flat areas of surface or subaquatic lava flows. Such features are generally composed of highly fluid basalt lava, and can extend for tens or hundreds of miles across the underlying terrain. Morphology and stru ...

in the southern highlands of the planet

Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin at ...

. The plain is notable for its moderate number of

impact crater An impact crater is a circular depression in the surface of a solid astronomical object formed by the hypervelocity impact of a smaller object. In contrast to volcanic craters, which result from explosion or internal collapse, impact crater ...

s and abundant wrinkle ridges. It is also the location of the ancient

volcano A volcano is a rupture in the Crust (geology), crust of a Planet#Planetary-mass objects, planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and volcanic gas, gases to escape from a magma chamber below the surface. On Ear ...

Tyrrhena Mons ( Tyrrhena Patera). The

Hesperian The Hesperian is a geologic system and time period on the planet Mars characterized by widespread volcanic activity and catastrophic flooding that carved immense outflow channels across the surface. The Hesperian is an intermediate and transitio ...

time period on Mars is named after Hesperia Planum.Scott, D.H.; Carr, M.H. (1978). Geologic Map of Mars. U.S. Geological Survey Miscellaneous Investigations Series Map I-1083. Wikiterracimmeriaboundaries

Name origin

PIA00182-MC-22-MareTyrrhenumRegion-19980605

Most place names on Mars are derived from sources in the

Bible The Bible (from Koine Greek , , 'the books') is a collection of religious texts or scriptures that are held to be sacred in Christianity, Judaism, Samaritanism, and many other religions. The Bible is an anthologya compilation of texts ...

classical antiquity Classical antiquity (also the classical era, classical period or classical age) is the period of cultural history between the 8th century BC and the 5th century AD centred on the Mediterranean Sea, comprising the interlocking civilizations of ...

. '' Hesperia'' is a Greco-Latin poetic term for "lands to the west," which to the

ancient Greeks Ancient Greece ( el, Ἑλλάς, Hellás) was a northeastern Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of classical antiquity ( AD 600), that comprised a loose collection of cult ...

and

Romans Roman or Romans most often refers to: *Rome, the capital city of Italy * Ancient Rome, Roman civilization from 8th century BC to 5th century AD *Roman people, the people of ancient Rome *''Epistle to the Romans'', shortened to ''Romans'', a lette ...

meant

Italy Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical ...

, while

Spain , image_flag = Bandera de España.svg , image_coat = Escudo de España (mazonado).svg , national_motto = ''Plus ultra'' (Latin)(English: "Further Beyond") , national_anthem = (English: "Royal March") , i ...

was referred as ''Hesperia Ultima'' . ''Planum'' (pl. ''plana'') is

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

for plateau or high plain. It is a descriptor term used in planetary geology for a relatively smooth, elevated terrain on another

planet A planet is a large, rounded astronomical body that is neither a star nor its remnant. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a you ...

moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...

.USGS Gazetteer of Planetary Nomenclature. http://planetarynames.wr.usgs.gov/DescriptorTerms. The Hesperia region of Mars was named by Italian astronomer

Giovanni Schiaparelli Giovanni Virginio Schiaparelli ( , also , ; 14 March 1835 – 4 July 1910) was an Italian astronomer and science historian. Biography He studied at the University of Turin, graduating in 1854, and later did research at Berlin Observatory, ...

in 1877 for an intermediate-toned albedo feature centered at lat. 20°S, long. 240°W between two darker regions. Believing the dark areas were bodies of water, Schiaparelli interpreted Hesperia to be a

floodplain A floodplain or flood plain or bottomlands is an area of land adjacent to a river which stretches from the banks of its channel to the base of the enclosing valley walls, and which experiences flooding during periods of high discharge.Goudi ...

marsh A marsh is a wetland that is dominated by herbaceous rather than woody plant species.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p Marshes can often be found a ...

bridging two adjacent seas, the Mare Tyrrhenum and Mare Cimmerium. Although the existence of seas on Mars had been discounted by the early 20th century, the true nature of the region remained obscure until the

space age The Space Age is a period encompassing the activities related to the Space Race, space exploration, space technology, and the cultural developments influenced by these events, beginning with the launch of Sputnik 1 during 1957, and continuin ...

. In 1972, the Mariner 9 spacecraft showed that Hesperia was a cratered, wind-streaked plain. The

International Astronomical Union The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreac ...

(IAU) formally named the area Hesperia Planum in 1973. The dark areas flanking Hesperia Planum were found to be heavily cratered uplands. In 1979, the IAU designated the upland area to the west as Tyrrhena Terra and to the east as

Terra Cimmeria Terra Cimmeria is a large Martian region, centered at and covering at its broadest extent. It covers latitudes 15 N to 75 S and longitudes 170 to 260 W. It lies in the Eridania quadrangle. Terra Cimmeria is one part of the heavily cratered, ...

. (''Terra'' is a Latin descriptor term meaning land or continent.)

Location and physical description

Hesperia Planum is located along the broad northeastern rim of the giant Hellas impact basinIvanov, M. A.; Korteniemi, J.; Kostama, V.-P.; Aittola, M.; Raitala, J.; Glamoclija, M.; Marinangeli, L.; Neukum, G. (2005), "Major Episodes of the Hydrologic History in the Region of Hesperia Planum", Mars. ''J. Geophys. Res.,'' 110, E12S21, . and is centered at lat. 22.3°S, long. 110°E in the

Mare Tyrrhenum quadrangle The Mare Tyrrhenum quadrangle is one of a series of 30 quadrangle maps of Mars used by the United States Geological Survey (USGS) Astrogeology Research Program. This quadrangle is also referred to as MC-22 (Mars Chart-22). It contains parts o ...

(MC-22). A small part of this region in the south is found in the

Hellas quadrangle The Hellas quadrangle is one of a series of 30 quadrangle maps of Mars used by the United States Geological Survey (USGS) Astrogeology Research Program. The Hellas quadrangle is also referred to as MC-28 (Mars Chart-28). The Hellas quadrangle c ...

. It has a maximum width of 1,700 km (1,056 mi) and covers an area of about 2 million km² (772,000 sq. mi).Gregg, T. K. P.; Crown, D. A. (2005)
''What is Hesperia Planum, Mars? An Examination of Multiple Working Hypotheses''.
(PDF) 36th Lunar and Planetary Science Conference, Abstract #1962. At large scales (>), Hesperia Planum appears smooth and level, having a relatively uniform surface elevation of above Mars datum. The plain's surface is lower in elevation than the surrounding uplands of Tyrrhena Terra and Terra Cimmeria and is slightly tilted to the south, with a mean regional slope of about 0.03°. In high-resolution images (

Geology

Hesperia Planum is generally interpreted to be composed of flood lavas, although layered

volcaniclastic Volcaniclastics are geologic materials composed of broken fragments ( clasts) of volcanic rock. These encompass all clastic volcanic materials, regardless of what process fragmented the rock, how it was subsequently transported, what environment it ...

lacustrine A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much larger ...

(lake-bed) sediments cannot be ruled out.Gregg, T. K. P.; de Silva, S. (2009). Tyrrhena Patera and Hesperia Planum, Mars: New Insights (and Old Interpretations) from High-Resolution Imagery. 40th Lunar and Planetary Science Conference, Abstract #1700. http://www.lpi.usra.edu/meetings/lpsc2009/pdf/1700.pdf. The lavas appear to partly fill a large, irregular topographic depression that existed in

Noachian The Noachian is a geologic system and early time period on the planet Mars characterized by high rates of meteorite and asteroid impacts and the possible presence of abundant surface water. The absolute age of the Noachian period is uncertain ...

times. The rims of pre-existing impact craters are still visible in places, indicating that the lava deposits are 250–500 m in thickness. The volume of lavas within Hesperia Planum is comparable to that found in

large igneous province A large igneous province (LIP) is an extremely large accumulation of igneous rocks, including intrusive (sills, dikes) and extrusive (lava flows, tephra deposits), arising when magma travels through the crust towards the surface. The formation ...

s on Earth, such as the

Columbia River Basalt Group The Columbia River Basalt Group is the youngest, smallest and one of the best-preserved continental flood basalt province on Earth, covering over mainly eastern Oregon and Washington, western Idaho, and part of northern Nevada. The basalt grou ...

Impact cratering and age

The moderate amount of cratering on Hesperia Planum indicates that the plain has an intermediate age in Martian history. In planetary geology, the number density of impact craters is a measure of the relative age of a planetary surface. Heavily cratered surfaces are old, and sparsely cratered surfaces are young. Hesperia Planum is the type locality for the

System and time period. The lavas making up Hesperia Planum define the base of the Hesperian System. They erupted at the beginning of the Hesperian Period around 3700 million years ago. (Mars itself, along with the other planets, formed about 4500 million years ago.) Hesperian lavas are younger than the rocks in the heavily cratered

terrains but older than rocks formed during the more recent Amazonian Period. (See

Geology of Mars The geology of Mars is the scientific study of the surface, crust, and interior of the planet Mars. It emphasizes the composition, structure, history, and physical processes that shape the planet. It is analogous to the field of terrestrial geo ...

Wrinkle ridges

Wrinkle ridges are long, linear

topographic Topography is the study of the forms and features of land surfaces. The topography of an area may refer to the land forms and features themselves, or a description or depiction in maps. Topography is a field of geoscience and planetary scien ...

highs with a distinctive morphology that consists of a low, broad arch topped by a narrow crenulated ridge (pictured left). They are common features on the Moon where they occur exclusively within lava flow plains (the lunar

maria Maria may refer to: People * Mary, mother of Jesus * Maria (given name), a popular given name in many languages Place names Extraterrestrial * 170 Maria, a Main belt S-type asteroid discovered in 1877 * Lunar maria (plural of ''mare''), large, ...

). Their occurrence on Mars is thought to reflect a similar volcanic association. Thus, areas on Mars with abundant wrinkle ridges are interpreted as plains formed by very fluid basaltic lava (

flood basalt A flood basalt (or plateau basalt) is the result of a giant volcanic eruption or series of eruptions that covers large stretches of land or the ocean floor with basalt lava. Many flood basalts have been attributed to the onset of a hotspot reac ...

s). The ridges themselves are believed to be the surface expression of

thrust fault A thrust fault is a break in the Earth's crust, across which older rocks are pushed above younger rocks. Thrust geometry and nomenclature Reverse faults A thrust fault is a type of reverse fault that has a dip of 45 degrees or less. If ...

s formed after the lava flows were emplaced. They are not volcanic features, but secondary,

tectonic Tectonics (; ) are the processes that control the structure and properties of the Earth's crust and its evolution through time. These include the processes of mountain building, the growth and behavior of the strong, old cores of continents ...

structures that form in dense, competent rocks (such as layered basalts) that have undergone compressional stress. Hesperian-aged "ridged plains" like Hesperia Planum cover about 30% of the Martian surface.Greeley, R.; Spudis, P. (1981). Volcanism on Mars. ''Rev. Geophys. Space Phys.,'' 19(1), 13–41.

Tyrrhenus Mons

Tyrrhenus Mons ( Tyrrhena Patera) is an eroded, low-lying volcano in the western part of Hesperia Planum. It is one of the oldest large central-vent volcanoes on the planetGreeley, R.; Crown, D.A. (1990). Volcanic Geology of Tyrrhena Patera, Mars. ''J. Geophys. Res.,'' 95(B5), 7133–7149. and a member of a class of volcanoes called highland paterae, which erupted mainly in the Late

and Early

.Crown, D. A.; Berman, D. C.; Gregg, T. K. P. (2007). Geologic Diversity and Chronology of Hesperia Planum, Mars. 38th Lunar and Planetary Science Conference, Abstract #1169. http://www.lpi.usra.edu/meetings/lpsc2007/pdf/1169.pdf. Tyrrhenus Mons stands only 1.5 km above the surrounding plains. At its center lies a 40 km diameter depression, or

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 ...

, from which radiate numerous flat-floored valleys and ridges that suggest the volcano has been highly eroded. The low relief of Tyrrhenus Mons combined with its degraded state indicate the volcano consists largely of

friable Friability ( ), the condition of being friable, describes the tendency of a solid substance to break into smaller pieces under duress or contact, especially by rubbing. The opposite of friable is indurate. Substances that are designated hazardous, ...

and easily eroded material such as

volcanic ash Volcanic ash consists of fragments of rock, mineral crystals, and volcanic glass, created during volcanic eruptions and measuring less than 2 mm (0.079 inches) in diameter. The term volcanic ash is also often loosely used to refer ...

. The ash was likely derived from the interaction of

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 ...

with

groundwater Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidated ...

or ice.Carr, 2006, pp. 69, 74, Fig. 3.33.

Dunes

ESP 045822 1680dunes.jpg, Dunes, as seen by HiRISE under HiWish program 45822 1680dunesclose.jpg, Close view of dunes, as seen by HiRISE under HiWish program 45822 1680color.jpg, Close, color view of dunes as seen by HiRISE under HiWish program Ripples are visible on dune surface.

Interactive Mars map

References

Bibliography and recommended reading

* Boyce, Joseph, M. (2008). ''The Smithsonian Book of Mars;'' Konecky & Konecky: Old Saybrook, CT, * Carr, Michael, H. (2006). ''The Surface of Mars;'' Cambridge University Press: Cambridge, UK, . * Hartmann, William, K. (2003). ''A Traveler’s Guide to Mars: The Mysterious Landscapes of the Red Planet;'' Workman: New York, . * Morton, Oliver (2003). ''Mapping Mars: Science, Imagination, and the Birth of a World;'' Picador: New York, . * Sheehan, William (1996). ''The Planet Mars: A History of Observation & Discovery;'' University of Arizona Press: Tucson, AZ, . http://www.uapress.arizona.edu/onlinebks/MARS/CONTENTS.HTM .

External links

Geologic Map of Reull Vallis Region of Mars
includes a portion of southern Hesperia Planum, by Astrogeology Science Center, U.S. Geological Survey {{Portal bar, Solar System Lava fields Plains on Mars Mare Tyrrhenum quadrangle Hellas quadrangle