The geological history of Mars follows the physical evolution of
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 ...
as substantiated by observations, indirect and direct measurements, and various inference techniques. Methods dating back to 17th century techniques developed by
Nicholas Steno
Niels Steensen ( da, Niels Steensen; Latinized to ''Nicolaus Steno'' or ''Nicolaus Stenonius''; 1 January 1638 – 25 November 1686[law of superposition
The law of superposition is an axiom that forms one of the bases of the sciences of geology, archaeology, and other fields pertaining to geological stratigraphy. In its plainest form, it states that in undeformed stratigraphic sequences, the ...](_blank ...<br></span></div>, including the so-called <div class=)
and
stratigraphy
Stratigraphy is a branch of geology concerned with the study of rock (geology), rock layers (Stratum, strata) and layering (stratification). It is primarily used in the study of sedimentary rock, sedimentary and layered volcanic rocks.
Stratigrap ...
, used to estimate the geological histories of Earth and the Moon, are being actively applied to the data available from several Martian observational and measurement resources. These include the landers, orbiting platforms, Earth-based observations, and Martian meteorites.
Observations of the surfaces of many
Solar System
The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar S ...
bodies reveal important clues about their evolution. For example, a lava flow that spreads out and fills a large impact crater is likely to be younger than the crater. On the other hand, a small crater on top of the same lava flow is likely to be younger than both the lava and the larger crater since it can be surmised to have been the product of a later, unobserved, geological event. This principle, called the
law of superposition
The law of superposition is an axiom that forms one of the bases of the sciences of geology, archaeology, and other fields pertaining to geological stratigraphy. In its plainest form, it states that in undeformed stratigraphic sequences, the ...
, along with other principles of
stratigraphy
Stratigraphy is a branch of geology concerned with the study of rock (geology), rock layers (Stratum, strata) and layering (stratification). It is primarily used in the study of sedimentary rock, sedimentary and layered volcanic rocks.
Stratigrap ...
first formulated by
Nicholas Steno
Niels Steensen ( da, Niels Steensen; Latinized to ''Nicolaus Steno'' or ''Nicolaus Stenonius''; 1 January 1638 – 25 November 1686[Paleozoic
The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon.
The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838
by combining the Greek words ''palaiós'' (, "old") and ' ...](_blank ...<br></span></div> in the 17th century, allowed geologists of the 19th century to divide the history of the Earth into the familiar eras of <div class=)
,
Mesozoic
The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceo ...
, and
Cenozoic
The Cenozoic ( ; ) is Earth's current geological era, representing the last 66million years of Earth's history. It is characterised by the dominance of mammals, birds and flowering plants, a cooling and drying climate, and the current configura ...
. The same methodology was later applied to the
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 ...
and then to Mars.
![Lava flow and crater ejecta](https://upload.wikimedia.org/wikipedia/commons/2/28/Lava_flow_and_crater_ejecta.JPG)
Another stratigraphic principle used on planets where impact craters are well preserved is that of crater number density. The number of craters greater than a given size per unit surface area (usually million km
2) provides a relative age for that surface. Heavily cratered surfaces are old, and sparsely cratered surfaces are young. Old surfaces have many big craters, and young surfaces have mostly small craters or none at all. These stratigraphic concepts form the basis for the Martian geologic timescale.
Relative ages from stratigraphy
Stratigraphy establishes the relative ages of layers of rock and sediment by denoting differences in composition (solids, liquids, and trapped gasses). Assumptions are often incorporated about the rate of deposition, which generates a range of potential age estimates across any set of observed sediment layers.
Absolute ages
The primary technique for calibrating the ages to the Common Era calendar is radiometric dating. Combinations of different radioactive materials can improve the uncertainty in an age estimate based on any one isotope.
By using stratigraphic principles,
rock units' ages can usually only be determined
relative to each other. For example, knowing that Mesozoic rock
strata
In geology and related fields, a stratum ( : strata) is a layer of rock or sediment characterized by certain lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by visible surfaces known as ei ...
making up the
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...
System
A system is a group of Interaction, interacting or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and influenced by its environment (systems), environment, is described by its boundaries, ...
lie on top of (and are therefore younger than) rocks of the
Jurassic
The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The J ...
System reveals nothing about how long ago the Cretaceous or Jurassic Periods were. Other methods, such as
radiometric dating
Radiometric dating, radioactive dating or radioisotope dating is a technique which is used to date materials such as rocks or carbon, in which trace radioactive impurities were selectively incorporated when they were formed. The method compares t ...
, are needed to determine
absolute ages in geologic time. Generally, this is only known for rocks on the Earth. Absolute ages are also known for selected rock units of the Moon based on samples returned to Earth.
Assigning absolute ages to rock units on Mars is much more problematic. Numerous attempts have been made over the years to determine an absolute Martian
chronology
Chronology (from Latin ''chronologia'', from Ancient Greek , ''chrónos'', "time"; and , '' -logia'') is the science of arranging events in their order of occurrence in time. Consider, for example, the use of a timeline or sequence of events. I ...
(timeline) by comparing estimated impact cratering rates for Mars to those on the Moon. If the rate of impact crater formation on Mars by crater size per unit area over geologic time (the production rate or flux) is known with precision, then crater densities also provide a way to determine absolute ages. Unfortunately, practical difficulties in crater counting and uncertainties in estimating the flux still create huge uncertainties in the ages derived from these methods. Martian meteorites have provided datable samples that are consistent with ages calculated thus far, but the locations on Mars from where the meteorites came (provenance) are unknown, limiting their value as
chronostratigraphic
Chronostratigraphy is the branch of stratigraphy that studies the ages of rock strata in relation to time.
The ultimate aim of chronostratigraphy is to arrange the sequence of deposition and the time of deposition of all rocks within a geologic ...
tools. Absolute ages determined by crater density should therefore be taken with some skepticism.
Crater density timescale
Studies 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 craters ...
densities on the Martian surface have delineated four broad
periods in the planet's
geologic history. The periods were named after places on Mars that have large-scale surface features, such as large craters or widespread lava flows, that date back to these time periods. The absolute ages given here are only approximate. From oldest to youngest, the time periods are:
*
Pre-Noachian Represents the interval from the accretion and differentiation of the planet about 4.5 billion years ago (
Gya
A billion years or giga-annum (109 years) is a unit of time on the petasecond scale, more precisely equal to seconds (or simply 1,000,000,000 years).
It is sometimes abbreviated Gy, Ga ("giga-annum"), Byr and variants. The abbreviations Gya or ...
) to the formation of the
Hellas impact basin, between 4.1 and 3.8 Gya. Most of the geologic record of this interval has been erased by subsequent erosion and high impact rates. The
crustal dichotomy
Crust may refer to:
Common meanings Food
* Crust (baking), the outer layer composed of pastry or salt
* Crust, the bread foundation of pizza
* Bread crust, the dense surface layer of bread
Physical sciences
* Crust (geology), the outer l ...
is thought to have formed during this time, along with the
Argyre and
Isidis basins.
*
Noachian Period (named after
Noachis Terra
Noachis Terra (; lit. "Land of Noah") is an extensive southern landmass (''terra'') of the planet Mars. It lies west of the giant Hellas impact basin, roughly between the latitudes −20° and −80° and longitudes 30° west and 30° east, cent ...
): Formation of the oldest extant surfaces of Mars between 4.1 and about 3.7 billion years ago (Gya). Noachian-aged surfaces are scarred by many large impact craters. The
Tharsis bulge
Tharsis () is a vast volcanic plateau centered near the equator in the western hemisphere of Mars. The region is home to the largest volcanoes in the Solar System, including the three enormous shield volcanoes Arsia Mons, Pavonis Mons, and As ...
is thought to have formed during the Noachian, along with extensive erosion by liquid water producing river
valley networks. Large lakes or oceans may have been present.
*
Hesperian Period (named after
Hesperia Planum
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 ( Tyrrhe ...
): 3.7 to approximately 3.0 Gya. Marked by the formation of extensive lava plains. The formation of
Olympus Mons
Olympus Mons (; Latin for Mount Olympus) is a large shield volcano on Mars. The volcano has a height of over 21.9 km (13.6 mi or 72,000 ft) as measured by the Mars Orbiter Laser Altimeter (MOLA). Olympus Mons is about two and a h ...
probably began during this period. Catastrophic releases of water carved extensive outflow channels around Chryse Planitia and elsewhere. Ephemeral lakes or seas may have formed in the northern lowlands.
*
Amazonian Period
The geological history of Mars follows the physical evolution of Mars as substantiated by observations, indirect and direct measurements, and various inference techniques. Methods dating back to 17th century techniques developed by Nicholas Steno, ...
(named after
Amazonis Planitia
Amazonis Planitia (, Latin ''Amāzŏnis'') is one of the smoothest plains on Mars. It is located between the Tharsis and Elysium volcanic provinces, to the west of Olympus Mons, in the Amazonis and Memnonia quadrangles, centered at . The plain' ...
): 3.0 Gya to present. Amazonian regions have few meteorite impact craters but are otherwise quite varied. Lava flows, glacial/
periglacial
Periglaciation (adjective: "periglacial", also referring to places at the edges of glacial areas) describes geomorphic processes that result from seasonal thawing of snow in areas of permafrost, the runoff from which refreezes in ice wedges and ot ...
activity, and minor releases of liquid water continued during this period.
The date of the Hesperian/Amazonian boundary is particularly uncertain and could range anywhere from 3.0 to 1.5 Gya. Basically, the Hesperian is thought of as a transitional period between the end of heavy bombardment and the cold, dry Mars seen today.
Mineral alteration timescale
In 2006, researchers using data from the OMEGA Visible and Infrared Mineralogical Mapping Spectrometer on board the
Mars Express
''Mars Express'' is a space exploration mission being conducted by the European Space Agency (ESA). The ''Mars Express'' mission is exploring the planet Mars, and is the first planetary mission attempted by the agency. "Express" originally ref ...
orbiter proposed an alternative Martian timescale based on the predominant type of mineral alteration that occurred on Mars due to different styles of chemical
weathering
Weathering is the deterioration of rocks, soils and minerals as well as wood and artificial materials through contact with water, atmospheric gases, and biological organisms. Weathering occurs ''in situ'' (on site, with little or no movement), ...
in the planet's past. They proposed dividing the history of the Mars into three eras: the Phyllocian, Theiikian and Siderikan.
*Phyllocian (named after
phyllosilicate
Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of minerals and make up approximately 90 percent of Earth's crust.
In mineralogy, silica (silicon dioxide, ) is usually consid ...
or clay minerals that characterize the era) lasted from the formation of the planet until around the Early Noachian (about 4.0 Gya). OMEGA identified outcropping of phyllosilicates at numerous locations on Mars, all in rocks that were exclusively Pre-Noachian or Noachian in age (most notably in rock exposures in
Nili Fossae
Nili Fossae is a group of large, concentric grabens on Mars, in the Syrtis Major quadrangle. They have been eroded and partly filled in by sediments and clay-rich ejecta from a nearby giant impact crater, the Isidis basin. It is at approximat ...
and
Mawrth Vallis
Mawrth Vallis () (Mawrth means "Mars" in Welsh) is a valley on Mars, located in the Oxia Palus quadrangle at 22.3°N, 343.5°E with an elevation approximately two kilometers below datum. Situated between the southern highlands and northern lowlan ...
). Phyllosillicates require a water-rich, alkaline environment to form. The Phyllocian era correlates with the age of
valley network formation on Mars, suggesting an early climate that was conducive to the presence of abundant surface water. It is thought that deposits from this era are the best candidates in which to search for evidence of past life on the planet.
*Theiikian (named after sulphurous in Greek, for the
sulphate minerals that were formed) lasted until about 3.5 Gya. It was an era of extensive
volcanism
Volcanism, vulcanism or volcanicity is the phenomenon of eruption of molten rock (magma) onto the surface of the Earth or a solid-surface planet or moon, where lava, pyroclastics, and volcanic gases erupt through a break in the surface called ...
, which released large amounts of
sulphur dioxide
Sulfur dioxide (IUPAC-recommended spelling) or sulphur dioxide (traditional Commonwealth English) is the chemical compound with the formula . It is a toxic gas responsible for the odor of burnt matches. It is released naturally by volcanic activ ...
(SO
2) into the atmosphere. The SO
2 combined with water to create a sulphuric acid-rich environment that allowed the formation of hydrated sulphates (notably
kieserite
Kieserite, or magnesium sulfate monohydrate, is a hydrous magnesium sulfate mineral with formula (MgSO4·H2O).
It has a vitreous luster and it is colorless, grayish-white or yellowish. Its hardness is 3.5 and crystallizes in the monoclinic cry ...
and
gypsum
Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula . It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, blackboard or sidewalk chalk, and drywall. ...
).
*Siderikan (named for iron in Greek, for the iron oxides that formed) lasted from 3.5 Gya until the present. With the decline of volcanism and available water, the most notable surface weathering process has been the slow oxidation of the iron-rich rocks by atmospheric
peroxide
In chemistry, peroxides are a group of compounds with the structure , where R = any element. The group in a peroxide is called the peroxide group or peroxo group. The nomenclature is somewhat variable.
The most common peroxide is hydrogen p ...
s producing the red
iron oxide
Iron oxides are chemical compounds composed of iron and oxygen. Several iron oxides are recognized. All are black magnetic solids. Often they are non-stoichiometric. Oxyhydroxides are a related class of compounds, perhaps the best known of whic ...
s that give the planet its familiar colour.
ImageSize = width:800 height:50
PlotArea = left:15 right:15 bottom:20 top:5
AlignBars = early
Period = from:-4500 till:0
TimeAxis = orientation:horizontal
ScaleMajor = unit:year increment:500 start:-4500
ScaleMinor = unit:year increment:100 start:-4500
Colors =
id:sidericol value:rgb(1,0.4,0.3)
id:theiicol value:rgb(1,0.2,0.5)
id:phyllocol value:rgb(0.7,0.4,1)
PlotData=
align:center textcolor:black fontsize:8 mark:(line,black) width:25 shift:(0,-5)
text:Siderikan from:-3500 till:0 color:sidericol
text:Theiikian from:-4000 till:-3500 color:theiicol
text:Phyllocian from:start till:-4000 color:phyllocol
References
Citations
*
*
External links
Mars - Geologic Map(
USGS
The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, a ...
, 2014)
original/
crop
A crop is a plant that can be grown and harvested extensively for profit or subsistence. When the plants of the same kind are cultivated at one place on a large scale, it is called a crop. Most crops are cultivated in agriculture or hydroponic ...
/
full video (00:56).
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