Areology (after Ares), or simply the "geology" of Mars, is the study of the composition, structure, physical properties, history and the processes that shape the planet Mars. It is a specific case of the more general astrogeology. In Greek mythology, Ares (in Greek, Άρης — battle strife)[1] is the son of Zeus (king of the gods) and Hera. ... Note: This article contains special characters. ... Astrogeologist and NASA astronaut Harrison Jack Schmitt collecting lunar samples during the Apollo 17 mission Astrogeology is a planetary science discipline concerned with the geology of the celestial bodies such as the planets and their moons, asteroids, comets, and meteorites. ...

Timeline

The Martian geological timescale (or perhaps more properly the areologic timescale) has three broad epochs defined by the number of impact craters on the surface; older surfaces have more craters. The epochs are named after places on Mars that belong to those time periods. The precise timing of these periods is not known because there are several competing models describing the rate of meteor fall on Mars, dates given here are approximate. From oldest to youngest, the time periods are: The table and timeline of geologic periods presented here is in accordance with the dates and nomenclature proposed by the International Commission on Stratigraphy. ... A division of geologic time less than a period and greater than an age. ... Tycho crater on Earths moon. ... Photo of a burst of meteors with extended exposure time A meteor is the visible path of a meteoroid that enters the Earths (or another bodys) atmosphere, commonly called a shooting star or falling star. ...

• Noachian epoch (named after Noachis Terra): Formation of Mars to between 3800 and 3500 million years ago. Noachian age surfaces are scarred by many large impact craters. The Tharsis bulge is thought to have formed during this period, with extensive flooding by liquid water late in the epoch.
• Hesperian epoch (named after Hesperia Planum): 3500 million years ago to 1800 million years ago. The Hesperian epoch is marked by the formation of extensive lava plains.
• Amazonian epoch (named after Amazonis Planitia): 1800 million years ago to present. Amazonian regions have few meteorite impact craters but are otherwise quite varied. Olympus Mons formed during this period along with lava flows elsewhere on Mars.

Noachis Terra (lit. ... Categories: Stub | Mars ... Amazonis Planitia is one of the smoothest plains on Mars. ... Olympus Mons Olympus Mons (Latin, Mount Olympus) is the tallest known mountain in our solar system, located on the planet Mars at approximately . ...

Alternative timeline

Based on recent observations made by the OMEGA Visible and Infrared Mineralogical Mapping Spectrometer on board the Mars Express orbiter, the principal investigator of the OMEGA spectrometer has proposed an alternative timeline based upon the correlation between the mineralogy and geology of the planet. This proposed timeline divides the history of the planet into 3 epochs; the Phyllocian, Theiikian and Siderikan.^[1] Concept model of the Mars Express spacecraft Mars Express is a Mars exploration mission of the European Space Agency and the first planetary mission attempted by the agency. ...

• Phyllocian (named after the clay-rich phyllosilicate minerals that characterize the epoch) lasted from the formation of the planet until around 4000 million years ago. In order for the phyllosilicates to form an alkaline water environment would have been present. It is thought that deposits from this era are the best candidates to search for evidence of past life on the planet. The equivalent on earth is much of the hadean eon .

• Theiikian (named, in Greek, after the sulfate minerals that were formed), lasting until about 3500 million years ago, was a period of volcanic activity. In addition to lava, gasses - and in particular sulfur dioxide - were released, combining with water to create sulfates and an acidic environment . The equivalent on earth is the eoarchean era and the beginning of the paleoarchean era .

• Siderikan, from 3500 million years ago until the present. With the end of volcanism and the absence of liquid water, the most notable geological process has been the oxidation of the iron-rich rocks by atmospheric peroxides, leading to the red iron oxides that give the planet its familiar color . The equivalent on earth is most of the archean all of the proterozoic and up to now .

The name Hadean refers to the geologic period before 3800 million years ago (mya). ... This article is about volcanoes in geology. ... In the geologic timescale, the Eoarchean or EA was an era that lasted from about 3800 MYA to 3600 MYA. It is the first part of the Archaean eon and the first part of the Precambrian eon. ... The Paleoarchean is a geologic era within the Archaean. ... Peroxide has three distinct meanings: // Main article: hydrogen peroxide In common usage, peroxide is an aqueous solution of hydrogen peroxide (HOOH or H2O2) sold for use as a disinfectant or mild bleach. ... Iron oxide pigment There are a number of iron oxides: Iron oxides Iron(II) oxide or ferrous oxide (FeO) The black-coloured powder in particular can cause explosions as it readily ignites. ... The Archean is a geologic eon; it is a somewhat antiquated term for the time span between 2500 million years before the present and 3800 million years before the present. ... In geology, the Proterozoic is an eon before the first abundant complex life on Earth. ...

Surface

The surface of Mars is thought to be primarily composed of basalt, based upon the Martian meteorite collection and orbital observations. There is some evidence that some portion of the Martian surface might be more silica-rich than typical basalt, perhaps similar to andesitic rocks on Earth, though these observations may also be explained by silica glass, phyllosilicates, or opal. Much of the surface is deeply covered by dust as fine as talcum powder. Note: This article contains special characters. ... Basalt Columnar basalt at Sheepeater Cliff in Yellowstone Basalt (IPA: ) is a common gray to black volcanic rock. ... A Martian meteorite is a meteorite that has landed on Earth but is believed to have originated from Mars. ... Basalt Columnar basalt at Sheepeater Cliff in Yellowstone Basalt (IPA: ) is a common gray to black volcanic rock. ... Andesite is an igneous, volcanic (extrusive) rock, of intermediate composition, with aphanitic to porphyritic texture. ...

Magnetic field

Observations of the magnetic fields on Mars by the Mars Global Surveyor spacecraft have revealed that parts of the planet's crust have been magnetized. This magnetization has been compared to alternating bands found on the ocean floors of Earth. One theory, published in 1999 and reexamined in October 2005 with the help of the Mars Global Surveyor, is that these bands are evidence of the past operation of plate tectonics on Mars.^[2] To meet Wikipedias quality standards, this article may require cleanup. ... Artists conception of Mars Global Surveyor (NASA) The Mars Global Surveyor (MGS) is a US spacecraft developed by NASA and the Jet Propulsion Laboratory and launched November 1996. ... Earth cutaway from core to exosphere. ... Artists conception of Mars Global Surveyor (NASA) The Mars Global Surveyor (MGS) is a US spacecraft developed by NASA and the Jet Propulsion Laboratory and launched November 1996. ... Bridge across the Álfagjá rift valley in southwest Iceland, the boundary of the Eurasian and North American continental tectonic plates. ...

Water

Liquid water

This article documents a current event. Information may change rapidly as the event progresses.

Mosaic shows some spherules partly embedded.

Among the findings from the Opportunity rover is the presence of hematite on Mars in the form of small spheres on the Meridiani Planum. The spheres are only a few millimeters in diameter and are believed to have formed as rock deposits under watery conditions billions of years ago. Other minerals have also been found containing forms of sulfur, iron or bromine such as jarosite. This and other evidence led a group of 50 scientists to conclude in the December 9, 2004 edition of the journal Science that "Liquid water was once intermittently present at the Martian surface at Meridiani, and at times it saturated the subsurface. Because liquid water is a key prerequisite for life, we infer conditions at Meridiani may have been habitable for some period of time in Martian history". Later studies suggested that this liquid water was actually acid because of the types of minerals found at the location. On the opposite side of the planet the mineral goethite, which (unlike hematite) forms only in the presence of water, along with other evidence of water, has also been found by the Spirit rover in the "Columbia Hills". Image File history File links Current_event_marker. ... The image is from one of the Mars Exploration Rovers File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... The image is from one of the Mars Exploration Rovers File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Spheules still in their originating strata Martian spherules, also known as blueberries, are the abundant spherical hematite inclusions discovered by the Mars rover Opportunity at Meridiani Planum on the planet Mars. ... The mission patch for Opportunity, featuring Duck Dodgers (Daffy Duck). ... Hematite (AE) or haematite (BE) is the mineral form of Iron(III) oxide, (Fe2O3), one of several iron oxides. ... Spheules still in their originating strata Martian spherules, also known as blueberries, are the abundant spherical hematite inclusions discovered by the Mars rover Opportunity at Meridiani Planum on the planet Mars. ... Mars Exploration Rover Opportunity looks southwest across Meridiani Planum; the Rovers discarded backshell and parachute are visible in the distance Hematite deposits in Meridiani Planum mapped from orbit, with Opportunity rover landing site ellipse Meridiani Planum is a plain located 2 degrees south of Mars equator, in the westernmost... General Name, Symbol, Number sulfur, S, 16 Chemical series nonmetals Group, Period, Block 16, 3, p Appearance lemon yellow Atomic mass 32. ... General Name, Symbol, Number iron, Fe, 26 Chemical series transition metals Group, Period, Block 8, 4, d Appearance lustrous metallic with a grayish tinge Atomic mass 55. ... General Name, Symbol, Number bromine, Br, 35 Chemical series halogens Group, Period, Block 17, 4, p Appearance gas/liquid: red-brown solid: metallic luster Atomic mass 79. ... Jarosite is a basic hydrous sulfate of potassium and iron with a chemical formula of KFe3(OH)6(SO4)2. ... December 9 is the 343rd day (344th in leap years) of the year in the Gregorian calendar. ... 2004 (MMIV) was a leap year starting on Thursday of the Gregorian calendar. ... Science is the journal of the American Association for the Advancement of Science (AAAS). ... Goethite is an iron bearing oxide mineral found in soil and other low temperature environments. ... The view of Columbia Hills from the MER-A landing site The Columbia Hills are a range of low hills inside Gusev crater on Mars. ...

Photo of Microscopic rock forms indicating past signs of water, taken by Opportunity

Recently, there has been evidence to suggest that liquid water flowed on the surface of Mars much more recently than thought, with the discovery of what look like two new channels that were not seen 10 years ago [1]. This image taken by MER-B (Mars Rover Opportunity) shows microscopic rock forms indicating past signs of water on Mars. ... This image taken by MER-B (Mars Rover Opportunity) shows microscopic rock forms indicating past signs of water on Mars. ... The mission patch for Opportunity, featuring Duck Dodgers (Daffy Duck). ...

Polar ice caps

Mars has polar ice caps that contain frozen water^[3] and carbon dioxide that change with the Martian seasons. Each cap has surface deposits of carbon dioxide ice that form a polar "hood" during Martian winter, and then sublimate during the summer uncovering the underlying cap surface of layered water ice and dust. The southern polar cap differs from the northern polar cap in that it appears to contain at least some permanent deposits of CO₂, which are changing on the time scale of years.^[4] Carbon dioxide is a chemical compound composed of one carbon and two oxygen atoms. ...

Ice patches

On 28 July 2005, the European Space Agency announced the existence of a crater partially filled with frozen water^[5]; some then interpreted the discovery as an "ice lake"^[6]. Images of the crater, taken by the High Resolution Stereo Camera on board the European Space Agency's Mars Express spacecraft, clearly show a broad sheet of ice in the bottom of an unnamed crater located on Vastitas Borealis, a broad plain that covers much of Mars' far northern latitudes, at approximately 70.5° North and 103° East. The crater is 35 km (23 mi) wide and about 2 km (1.2 mi) deep. July 28 is the 209th day (210th in leap years) of the year in the Gregorian Calendar, with 156 days remaining. ... 2005 (MMV) was a common year starting on Saturday of the Gregorian calendar. ... The European Space Agency (ESA), established in 1975, is an inter-governmental organization dedicated to the exploration of space, currently with 17 member states. ... The European Space Agency (ESA), established in 1975, is an inter-governmental organization dedicated to the exploration of space, currently with 17 member states. ... Concept model of the Mars Express spacecraft Mars Express is a Mars exploration mission of the European Space Agency and the first planetary mission attempted by the agency. ... Vastitas Borealis is the largest lowland region of Mars. ...

The height difference between the crater floor and the surface of the water ice is about 200 metres. ESA scientists have attributed most of this height difference to sand dunes beneath the water ice, which are partially visible. While scientists do not refer to the patch as a "lake", the water ice patch is remarkable for its size and for being present throughout the year. Deposits of water ice and layers of frost have been found in many different locations on the planet. This article is about the European Space Agency. ...

See also

• Life on Mars
• Geography of Mars
• Martian spiders

The infamous Face on Mars released on July 25, 1976. ... Topographic map of Mars, courtesy NASA Goddard Space Flight Center, from Mars Global Surveyor laser altimeter research led by Maria Zuber and David Smith. ... Martian spiders are geological formations thus far unique to the south polar region of Mars. ...

References

1. ^ http://www.theregister.co.uk/2006/04/21/three_mars_eras/
2. ^ "New Map Provides More Evidence Mars Once Like Earth" - Oct. 12, 2005 Goddard Space Flight Center Press release. URL accessed March 17, 2006.
3. ^ "Water at Martian south pole" - March 17, 2004 ESA Press release. URL accessed March 17, 2006.
4. ^ Orbiter's Long Life Helps Scientists Track Changes on Mars - Sept. 20, 2005 NASA Press release. URL accessed March 17, 2006.
5. ^ "Water ice in crater at Martian north pole" - July 27, 2005 ESA Press release. URL accessed March 17, 2006.
6. ^ "Ice lake found on the Red Planet" - July 29, 2005 BBC story. URL accessed March 17, 2006.