The Memnonia Region
MC-16
Leaving the Elysium Region at the southeast corner and entering the northeast corner of the Memnonia Region we begin the survey of the southern half of Mars.
Topographical Map of the Memnonia Region of Mars
The Memnonia Region, in the south includes heavily cratered highlands intersected, in the northeastern part, by Mangala Vallis. The north contains undulating wind-eroded deposits and the east contains lava flows from the Tharsis region. The quadrangle is a region of Mars that covers latitude -30° to 0° and longitude 135° to 180°.
Image of the Memnonia Region of Mars
The western part of Memnonia is a highly cratered highland region that exhibits a large range of crater degradation. Recently, evidence of water was found in the area. Layered sedimentary rocks were found in the wall and floor of Columbus Crater. These rocks could have been deposited by water or by wind. Hydrated minerals were found in some of the layers, so water may have been involved. Many ancient river valleys including Mangala Vallis, have been found in the Memnonia Region. Mangala appears to have begun with the formation of a graben, a set of faults that may have exposed an aquifer. Dark slope streaks and troughs (fossae) are present in this quadrangle.
The first area of importance we encounter is the Lucus Planum. It occupies the northeast corner of the Memnonia Region.
Lucus Planum Area
The Lucus Planum is a plateau that extends as far south as 3.96° S. 182° E. and covers a area of 1800 km.
Leading to the south from the Lucus Planum is the Memnonia Sulci.
The Memnonia Sulci
The Memnonia Sulci is part of the bigger area of the Medusae Fossae Formation. This region extends from the Lacus Planum area to the Amazonis Mensa in the northern part of the Memnonia Region. The Memnonia Sulci is located at 12.5°S 185°E
Continuing into a lowland area and back into the highlands we enter the Terra Sirenum. This area covers the remainder of the western part of the Memnonia Region, and it is heavily cratered terrain. Terra Sirenum is a large region in the southern hemisphere of the planet Mars. It is centered at 39.7°S 210°E and covers 3900 km at its broadest extent. It covers latitudes 10 to 70° South. Terra Sirenum is an upland area notable for massive cratering in the south and extends all the way into the next region the Phaethontis Region of Mars to the south. So it covers a huge amount of territory. It’s border to the east in the Memnonia Region would be the large and noticeable Mangala Valles. So you could say it covers about 2/3 of the Memnonia Region (excluding the Medusae Fossae area to the north)
Craters and Gullies in Terra Sirenum
At about 19°S 186°E we come to Ejriksson Crater. It is 49 km in diameter and was named for Leif Ericson the Norse explorer.
Ejriksson Crater
To the east of Ejriksson Crater at 18°S 196°E is Williams Crater.
Well-Preserved Crater Inside Williams Crater
Williams Crater is 126 km in diameter. The crater was named after Arthur Stanley Williams (1861 – November 21, 1938) an amateur astronomer. He dedicated his life to the telescopic observation of the planets.
South of Williams Crater we come to Dejnev Crater. It’s location is 26.2 degrees south latitude and 195.4 degrees east longitude.
Possible Phyllosilicates in Dejnev Crater
Dejnev Crater is 156 km in diameter. It is named for Semen Ivanovich Dejnev, a Russian geographer, explorer, and navigator (1605-1673).
South of this crater right on the border with the Region to the south we come to Columbus Crater.
Columbus Crater
Columbus Crater contains layers, also called strata. Many places on Mars show rocks arranged in layers. Sometimes the layers are of different colors. Light-toned rocks on Mars have been associated with hydrated minerals like sulfates. The Mars Rover Opportunity examined such layers close-up with several instruments. Scientists are excited about finding hydrated minerals such as sulfates and clays on Mars because they are usually formed in the presence of water. Places that contain clays and/or other hydrated minerals would be good places to look for evidence of life. Rock can form layers in a variety of ways. Volcanoes, wind, or water can produce layers. Columbus crater contains salts and clay minerals that may have formed in an ancient lake on Mars.
Going north we pass over part of then Mangala Fossae (which we will return to later) and come to Burton Crater. Burton Crater is located at 14°S 204°E.
Burton Crater
Burton Crater is 123 km in diameter and was named for Charles E. Burton (1846 – June 9, 1882) an Irish astronomer.
From there to the NNE is Marca Crater it is located at 10°S 202°E.
Marca Crater
Marca Crater is 81 km in diameter and is named after a Peru place name.
To the east of Marca Crater is Labou Vallis there are also numerous small Vallis to the north of Marca Crater as well. But of these the largest is the Labou Valles.
Labou Vallis Crater with Valleys
Labou Vallis is located at 9°S 207°E. Labou Vallis is 222 km in length and is named after a French word for Mars. Labou Vallis has dark slope streaks on its walls. The streaks are generally thought to be the dark material that has been exposed by bright dust moving down a steep slope in an avalanche. Many places on Mars show dark streaks on steep slopes like crater walls. It seems that the youngest streaks are dark; they become lighter with age. Often they begin as a small narrow spot then widen and extend downhill for hundreds of meters. They have been seen to travel around obstacles, like boulders. Several ideas have been advanced to explain the streaks. Some involve water or even the growth of organisms. It is most generally accepted that they represent avalanches of dust. The streaks appear in areas covered with dust. When a thin layer of dust is removed, the underlying surface is dark. Much of the Martian surface is covered with dust. Fine dust settles out of the atmosphere covering everything. We know a lot about this dust because the solar panels of the Mars Rovers get covered with dust, thus reducing their electrical energy.
The Labou Vallis goes northeastward until it comes to the Medusae Sulci, which is located at 5°S 200°E.
Erosional Exposure in Medusae Sulci
The Medusae Sulci is in the southern part of the Medusae Fossae Formation that run along the northern border of the Memnonia Region. The Medusae Fossae Formation is named for the Medusa of Greek mythology. "Fossae" is Latin for "trenches". The Medusae Fossae Formation is a soft, easily eroded deposit that extends for nearly 1,000 km along the equator of Mars. Sometimes, the formation appears as a smooth and gently undulating surface, however in places it is wind-sculpted into ridges and grooves. Radar imaging has suggested that the region may contain either extremely porous rock (for example volcanic ash) or deep layers of glacier-like ice deposits amounting to about the same quantity as is stored in Mars' south polar cap. Using a global climate model, a group of researchers headed by Laura Kerber found that the Medusae Fossae Formation could have easily been formed from ash from the volcanoes Apollinaris Mons, Arsia Mons, and possibly Pavonis Mons.
The Medusae Fossae Formation
Another evidence for a fine-grained composition is that the area gives almost no radar return. For this reason it has been called a "stealth" region. The formation is divided into three subunits (members) that are all considered to be Amazonian age, the youngest era in Martian geological history. Dust storms are frequent, especially when the spring season begins in the southern hemisphere. At that time, Mars is 40% closer to the sun. The orbit of Mars is much more elliptical then the Earth's. That is the difference between the farthest point from the sun and the closest point to the sun is very great for Mars, but only slight for the Earth. Also, every few years, the entire planet is engulfed in a global dust storm. When NASA's Mariner 9 craft arrived there in 1971, nothing could be seen through such a dust storm. Other global dust storms have also been observed, since that time.
Going east from here we come to Minos Valles located 8.2 degrees south latitude and 208.1 degrees east longitude.
Minos Valles
This overflow channel leads south for about 88 km. It is named for a river in Italy.
Next as we head east we come to the largest valley in the Memnonia Region the Mangala Valles. It is located at 11.6°S 211.0°E.
Mangala Valles (Note the video mentions Tharsis Region but the Main Valley of Mangala Valles is in the Memnonia Region).
Mangala Vallis is a major channel system that contains several basins which filled, then the overflow went through a series of spillways. One source of waters for the system was Memnonia Fossae, but water also probably came from a large basin centered at 40 degrees S. It is thought to be an outflow channel, carved by catastrophic and release of vast quantities of water across the Martian surface. This flooding was probably initiated by tectonic stretching and the formation of a graben at the channels' head, perhaps breaching a pressurized aquifer trapped beneath a thick "cryosphere" (layer of frozen ground) beneath the surface. There are many wind-sculpted ridges or yardangs covering many of the surfaces in the Mangala Valles region. "Mangala" comes from the word for Mars in Sanskrit.
Mangala Valles, as seen by HiRISE.
Mangala Vallis with a streamlined island, as seen by THEMIS.
Mangala Valles is 828 km long.
Tinia Valles is among a group of small Valles to the east of Mangala Valles. It is an ancient valley in the Memnonia Region of Mars, located at 4.7° south latitude and 211.5° east longitude. It is 18.7 km long and was named after a classical river in Italy. Tinia Valles has many dark slope streaks on its walls. These features are widely believed to be avalanches of a thin layer of bright dust that usually covers the dark surface beneath.
Tinia Valles
Going further east we come to the Amazonis Sulci which is the southern end of the Amazonis Mensa.. The Medusae Fossae Formation comes to an end in this area. The Amazonis Mensa is the continuation of the Gordii Dorsum in the Amazonis Region. It becomes the Amazonis Mensa in the Memnonia Region.
Sample of Terrain Near Amazonis Mensa and Gordii Dorsum
Terrain Near Amazonis Sulci
The Amazonis Sulci is located at 4°S 215°E. "Sulci" in Mars geography means like a furrow or groove similar to a brain's surface.
Going back to the southwest we cross the Mangala Valles and come to Cobres Crater at 11.5°S 206.5°E.
Cobres Crater
Cobres Crater is 94 km in diameter and is named after an Argentina place name.
Going south we next come to Mangala Fossa which covers quite a distance across the area from the southwest to the northeast crossing Mangala Valles into the Daedalia Planum.
Mangala Fossa near Mangala Valles
The Mangala Fossae stretches from 202°E to 218°E going at an angle in a northeasterly direction. Large troughs (long narrow depressions) are called fossae in the geographical language used for Mars. This term is derived from Latin; therefore fossa is singular and fossae is plural. Troughs form when the crust is stretched until it breaks. The stretching can be due to the large weight of a nearby volcano. A trough often has two breaks with a middle section moving down, leaving steep cliffs along the sides; such a trough is called a graben. It appears that the water started coming out of the surface to form Mangala Vallis when a graben was formed.
Going south a short distance we come to the Memnonia Fossa and right in it’s center is Bernard Crater. The crater is located at 27°S 206°E.
Volcanic Features in Bernard Crater
Bernard Crater: is a large crater in the Memnonia Region of Mars. It is 131.0 km in diameter and was named after P. Bernard, a French atmospheric scientist. The floor of the crater contains large cracks, which may be due to erosion.
Graben in Memnonia Fossae
Other ideas have been suggested for the formation of fossae. There is evidence that they are associated with dikes of magma. Magma might move along, under the surface, breaking the rock and more importantly melting ice. The resulting action would cause a crack to form at the surface. Dikes caused both by tectonic stretching (extension) and by dikes are found in Iceland. An example of a graben caused by a dike is shown below in the image Memnonia Fossae, as seen by HiRISE.
Going to the southeastern corner of the Memnonia Region we come to the Sirenum Fossae. It is on an angle cutting across the southern part the Region in a northeasterly direction. The Sirenum Fossae is a trough in the Memnonia Region of Mars, which starts at 34.9° south latitude in the Region to the south and 210° west longitude in the Memnonia Region. The Sirenum Fossae is 2,735 km long and was named after a classical albedo feature name. Troughs on Mars like this one are called Fossae. Sirenum Fossae is believed to have formed by movement along a pair of faults causing a center section to drop down. This kind of feature is called a graben.
Sirenum Fossae at 26°S 219°E
South of Sirenum Fossae we come to Koval’sky Crater.
Koval’sky Crater
Koval’sky Crater is located at 29°S 218.5°E it is 309 km in diameter. It is named after Marian Albertovich Kowalski (Russian: Мариан Альбертович Ковальский) (August 15, 1821 or October 15, 1821 – May 28, 1884 or July 9, 1884) was a Polish-Russian astronomer.
Going back north again we enter the we enter the Daedalia Planum. Daedalia Planum is a plateau on Mars located south of Arsia Mons at 21.8°S 232°E and appears to be relatively featureless plain with multiple lava flows and small craters with a few hills. Modern imagery suggests that it may more accurately be called a "fluctus" rather than a "planum". A planum is a plateau and a fluctus is terrain covered by an outflow of a volcano in Mars geographical terminology. There is evidence that an ancient 4500 km-diameter impact basin formed in the Noachian epoch may be centered in Daedalia Planum. It covers and area of 1800 km and covers the eastern 5th of the Memnonia Region.
The Daedalia Planum
