Olympus Mons is a very large shield volcano on the planet Mars. The volcano has a height of nearly 22 km as measured by the Mars Orbiter Laser Altimeter (MOLA). Olympus Mons is about two and a half times Mount Everest's height above sea level. It is the largest volcano, the tallest planetary mountain, and the second tallest mountain currently discovered in the Solar System, comparable to Rheasilvia on Vesta. In terms of surface area, Olympus Mons is the second-largest volcano in the solar system, second only to Earth's Tamu Massif. Olympus Mons is the youngest of the large volcanoes on Mars, having formed during Mars's Hesperian Period. It had been known to astronomers since the late 19th century as the albedo feature Nix Olympica. Its mountainous nature was suspected well before space probes confirmed its identity as a mountain.
Syrtis Major Planum is a "dark spot" located in the boundary between the northern lowlands and southern highlands of Mars just west of the impact basin Isidis in the Syrtis Major quadrangle. It was discovered, on the basis of data from Mars Global Surveyor, to be a low-relief shield volcano, but was formerly believed to be a plain, and was then known as Syrtis Major Planitia. The dark color comes from the basaltic volcanic rock of the region and the relative lack of dust.
Noctis Labyrinthus is a region of Mars between Valles Marineris and the Tharsis upland. It is located in the Phoenicis Lacus quadrangle. The region is notable for its maze-like system of deep, steep-walled valleys. The valleys and canyons of this region formed by faulting and many show classic features of grabens, with the upland plain surface preserved on the valley floor. In some places the valley floors are rougher, disturbed by landslides, and there are places where the land appears to have sunk down into pit-like formations. It is thought that this faulting was triggered by volcanic activity in the Tharsis region. Research described in December 2009 found a variety of minerals, including clays, sulfates, and hydrated silicas, in some of the layers.
Pavonis Mons is a large shield volcano located in the Tharsis region of the planet Mars. It is the middle member of a chain of three volcanic mountains that straddle the Martian equator between longitudes 235°E and 259°E. The volcano was discovered by the Mariner 9 spacecraft in 1971, and was originally called Middle Spot. Its name formally became Pavonis Mons in 1973. The equatorial location of its peak and its height make it the ideal terminus for a space elevator, and it has often been proposed as a space elevator location, especially in science fiction.
Ascraeus Mons is a large shield volcano located in the Tharsis region of the planet Mars. It is the northernmost and tallest of three shield volcanoes collectively known as the Tharsis Montes.
Arsia Mons is the southernmost of three volcanos on the Tharsis bulge near the equator of the planet Mars. To its north is Pavonis Mons, and north of that is Ascraeus Mons. The tallest volcano in the Solar System, Olympus Mons, is to its northwest. Its name comes from a corresponding albedo feature on a map by Giovanni Schiaparelli, which he named in turn after the legendary Roman forest of Arsia Silva.
The Tharsis Montes are three large shield volcanoes in the Tharsis region of the planet Mars. From north to south, the volcanoes are Ascraeus Mons, Pavonis Mons and Arsia Mons. Mons is the Latin word for mountain; it is a descriptor term used in astrogeology for mountainous features in the Solar System.
Alba Mons is an immense, low-lying volcano located in the northern Tharsis region of the planet Mars. It is the largest volcano on Mars in terms of area, with volcanic flow fields that extend for at least 1,350 km (840 mi) from its summit. Although the volcano has a span comparable to that of the United States, it reaches an elevation of only 6.8 km (22,000 ft) at its highest point. This is about one-third the height of Olympus Mons, the tallest volcano on the planet. The flanks of Alba Mons have very gentle slopes. The average slope along the volcano's northern flank is 0.5°, which is over five times lower than the slopes on the other large Tharsis volcanoes. In broad profile, Alba Mons resembles a vast but barely raised welt on the planet's surface. It is a unique volcanic structure with no counterpart on Earth or elsewhere on Mars.
Chryse Planitia is a smooth circular plain in the northern equatorial region of Mars close to the Tharsis region to the west, centered at 28.4°N 319.7°E. Chryse Planitia lies partially in the Lunae Palus quadrangle, partially in the Oxia Palus quadrangle, partially in the Mare Acidalium quadrangle. It is 1600 km or 994 mi in diameter and with a floor 2.5 km below the average planetary surface altitude, and is thought to be an ancient impact basin; it has several features in common with lunar maria, such as wrinkle ridges. The density of impact craters in the 100 to 2,000 metres range is close to half the average for lunar maria.
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 geology. In planetary science, the term geology is used in its broadest sense to mean the study of the solid parts of planets and moons. The term incorporates aspects of geophysics, geochemistry, mineralogy, geodesy, and cartography. A neologism, areology, from the Greek word Arēs (Mars), sometimes appears as a synonym for Mars's geology in the popular media and works of science fiction.
Volcanic activity, or volcanism, has played a significant role in the geologic evolution of Mars. Scientists have known since the Mariner 9 mission in 1972 that volcanic features cover large portions of the Martian surface. These features include extensive lava flows, vast lava plains, and the largest known volcanoes in the Solar System. Martian volcanic features range in age from Noachian to late Amazonian, indicating that the planet has been volcanically active throughout its history, and some speculate it probably still is so today. Both Earth and Mars are large, differentiated planets built from similar chondritic materials. Many of the same magmatic processes that occur on Earth also occurred on Mars, and both planets are similar enough compositionally that the same names can be applied to their igneous rocks and minerals.
Tharsis Tholus is an intermediate-sized shield volcano located in the eastern Tharsis region of the planet Mars. The volcano was discovered by the Mariner 9 spacecraft in 1972 and originally given the informal name Volcano 7. In 1973, the International Astronomical Union (IAU) officially designated it Tharsis Tholus. In planetary geology, tholus is the term for a small domical mountain, usually a volcano.
Ceraunius Fossae is an area of intensely fractured terrain in the northern Tharsis region of Mars. It lies directly south of the large volcano Alba Mons and consists of ancient highland crust that has been deformed by numerous parallel faults and tension cracks. In places, younger lava flows cover the fractured terrain, dividing it into several large patches or islands. It is found in the Tharsis quadrangle.
Ceraunius Tholus is a volcano on Mars located in the Tharsis quadrangle at 24.25° north latitude and 262.75° east longitude, part of the Uranius group of volcanoes. It is 130 km across, 5.5 km high and is named after a classical albedo feature name.
The Uranius group of volcanoes is located on planet Mars in the northeast part of Tharsis and includes Uranius Mons, Ceraunius Tholus, and Uranius Tholus.
Hesperia Planum is a broad lava plain in the southern highlands of the planet Mars. The plain is notable for its moderate number of impact craters and abundant wrinkle ridges. It is also the location of the ancient volcano Tyrrhena Mons. The Hesperian time period on Mars is named after Hesperia Planum.
For some time, scientists have thought that the location of the poles of Mars have shifted due to the great mass of volcanic material in the Tharsis dome which includes Olympus Mons, the highest volcano in the solar system. A study published in Nature supports this idea. For a period early in the history of Mars, the poles were about 20 degrees away from their present positions. At that time ice was deposited in a region called Dorsa Argentea Formation. Also, the Martian dichotomy was aligned along the equator. A band of rivers formed at around 25 degrees south carried water from the southern highlands to the northern lowlands. After the polar shift, the location of the dichotomy boundary and the band of river valleys shifted. Dorsa Argentea was no longer at the pole. To produce the change in the pole location, the tilt of the planet remained unchanged, rather the crust and mantle moved. They rotated around the core. This new study suggests that the volcanoes and the movement of the poles occurred at about the same time. Volcanoes were erupting when the rivers were flowing with water. Perhaps the volcanoes supplied much water to the atmosphere, as well as carbon dioxide to warm the atmosphere; these effects would provide water for the rivers.
The Thaumasia Planum of Mars lies south of Melas Chasmata and Coprates Chasmata. It is in the Coprates quadrangle. Its center is located at 21.66 S and 294.78 E. It was named after a classical albedo feature. The name was approved in 2006. Some forms on its surface are evidence of a flow of lava or water the Melas Chasma. Many wrinkle ridges and grabens are visible. One set of grabens, called Nia Fossae, seem to follow the curve of Melas Chasmata which lies just to the north.
The Thaumasia Plateau is a vast sloping volcanic plain in the western hemisphere of Mars, and is the most aereally extensive component of the Tharsis Rise. Syria Planum, Solis Planum, Sinai Planum, and Thaumasia Planum are the constituent sectors of the plateau, which sits between 8 km and 4 km above the surrounding southern highlands. It is bounded by vestigial basement terrains that predate the formation of Tharsis. This area has been proposed to be a drainage basin that sourced the floodwaters forming the outflow channels surrounding Chryse Planitia.
