Small Pale Red Planet Issue 3 Phase 3.1

The Coprates Region

MC-18

To begin, this Phase will be written differently than any of the other Phases before it.  This is due to the west-east orientation of the Valles Marineris.  Therefore we will be going from east to west and come back from west to east until this Phase ends.  Normally I write each Phase in a north-south and south-north orientation, but not this time for the reasons I have given above.

Topographical Map of Coprates Region

The Coprates Region goes from 45° to 90° west longitude and 0° to 30° south latitude on Mars. Coprates Region is famous for the "Grand Canyon of Mars" named the Valles Marineris Canyon System. Signs of water exist in this Region as ancient river valleys.  Networks of stream channels showing up as inverted terrain, and there is evidence of the past presence of lakes inside of Valles Marineris.  Valles Marineris (Latin for Mariner Valleys, named after the Mariner 9 Mars orbiter of 1971–72 which discovered it) is a system of canyons that runs along the Martian surface east of the Tharsis region. At more than 4,000 km (2,500 mi) long, 200 km (120 mi) wide and up to 7 km (23,000 ft) deep, the Valles Marineris rift system is one of the larger canyons of the Solar System, surpassed only by the rift valleys of Earth and (in length only) by Baltis Vallis on Venus.  The Valles Marineris is located along the equator of Mars, on the east side of the Tharsis Bulge, and stretches for nearly a quarter of the planet’s circumference.

Image of Coprates Region

The Valles Marineris system starts in the west with Noctis Labyrinthus; proceeding  eastward to the Tithonium and Ius Chasmata, then Melas, Candor and Ophir Chasmata, then Coprates Chasma, then Ganges, Capri and Eos Chasmata; finally it empties into an outflow channel region containing chaotic terrain that ends in the basin of Chryse Planitia. It has been recently suggested that Valles Marineris is a large tectonic "crack" in the Martian crust. Most researchers agree that this formed as the crust thickened in the Tharsis region to the west, and was subsequently widened by erosion.  However, near the eastern flanks of the rift there appear to be some channels that may have been formed by water or carbon dioxide.

Valles Marineris with labels (with associated Chasma). Image was taken with the Mars Odyssey's THEMIS.

There are at least four theories concerning it’s formation: Scientists believe that there was liquid water flowing on the Martian surface in the past. (1) Valles Marineris may have been formed by flowing water at this time. (2)Another hypothesis by McCauley in 1972 was that the canyons formed by withdrawal of subsurface magma. (3)Around 1989 Tanaka and Golombek proposed a theory of formation by tensional fracturing. (4)The most agreed upon theory today is that Valles Marineris was formed by rift faults like the East African Rift, later made bigger by erosion and collapsing of the rift walls.

Topographical Map of Valles Marineris and surrounding terrain (Tharsis Montes to the West and the Chryse Planitia to the East).

Because the Valles Marineris is thought to be a large rift valley, its formation is closely tied with the formation of the Tharsis Bulge (to the west). The Tharsis Bulge was formed from the Noachian to Late Hesperian period of Mars, in three stages. The first stage consisted of a combination of volcanism and isostatic (the state of balance, or the equilibrium of the Mar’s lithosphere) uplift; soon, however, the volcanism loaded the crust to a point at which the crust could no longer support the added weight of Tharsis, leading to widespread graben formation in the elevated regions of Tharsis. Stage two consisted of more volcanism and a loss of isostatic equilibrium; the source regions of the volcanism no longer resided underneath Tharsis, creating a very large load. Finally, the crust failed to hold up Tharsis and radial fractures, then the Valles Marineris, formed. Stage three mainly consisted of more volcanism and asteroid impacts. The crust, having already reached its failure point, just stayed in place and younger volcanoes formed. Tharsis volcanism involved very low viscosity magma, forming shield volcanoes similar to those of the Hawaiian Island chain, but, because there seems to be no minor or no current active plate tectonics on Mars, the hotspot activity led to very long histories of repeated volcanic eruptions at the same spots, creating some of the largest volcanoes in the solar system, including the biggest, Olympus Mons. 

 

The canyon's depth suggests that this location may be the best site for a manned outpost as it would have the highest natural air pressure on Mars. Equatorial solar irradiation and access to water would enhance this option still further. The Valles Marineris, the "Grand Canyon" of Mars, is over 3,000 km long and averages 8 km deep. Atmospheric pressure at the bottom would be some 25% higher than the surface average, 0.9 kPa vs. 0.7 kPa.

Outpost in Valles Marineris

1.  We begin our survey headed west between 0-5°S:

Tithonium Chasm is a large canyon in the Coprates Region of Mars at 4.6° south latitude and 90° east longitude. It is about 810 km long and was named after a classical albedo feature name.

Tithonium Chasma Layers, as seen by HiRISE. Location is 4.6 degrees south latitude and 270.4 degrees east longitude. Image was taken by the Mars Reconnaissance Orbiter's HiRISE

Next we come to the Tithonium Fossae.  Tithonium Fossae is located just north of Tithonium Chasma at 3°S 278°E.

Tithonium Fossae

To the northeast is the  Echus Chasma at 0°S 280°East.

Echus Chasma

Echus Chasma is a Chasma in the Lunae Planum high plateau north of the Valles Marineris canyon system of Mars. Clay has been found within it, meaning that water once sat there for a time.

Echus Chasma

Echus Chasma is approximately 100 km long and 10 km wide, with valleys ranging in depth from around 1 km to 4 km. It is the source region of the Kasei Valles outflow channel, which extends northward from it. It is situated just west of Hebes Chasma, to which it does not connect.

 

Going to the southeast from there we come to Perrotin Crater at 3°S 282°E.

Perrotin Crater

Perrotin Crater is 84 km in diameter and was named after Henri Joseph Anastase Perrotin (December 19, 1845 – February 29, 1904) who was a French astronomer.

 

Heading northeast from there we come to Hebes Chasma at 0° 283°E., right on the Equator and to it’s south.  This video will give you an idea of how big these Chasma in the Valles Marineris can be.

Hebes Chasma

Hebes Chasma is a large enclosed valley in the northern part of the Coprates Region , it may have once held water. Hydrated minerals have been found there. It is thought that large-scale underground springs of groundwater at different times burst to the surface to form deposits called Light Toned Deposits (LTD's). Some suggest the presence of  fossilized life forms may be found there because the deposits are relatively young.

 

The next area of interest we come to is Ophir Chasma to the southeast and is a part of the larger areas that make up the Valles Marineris.  It is located at 4°S 287° E.

 

 

Aqueous Sulfate Mineralogy

 

 

Ophir Chasma is a canyon in the Coprates quadrangle of Mars at 4° south latitude and 287° east longitude. It is about 317 km long and was named after a classical albedo feature name. 

 

Inside Ophir Chasma is the Ophir Mensa.  It is a square shaped mesa inside the Chasma at 4.5°S 287°E.

Ophir Mensa

Just north of the Ophir Chasma is the Juventae  Dorsa at 2.5°S 289°E.

East of the Juventae Dorsa we enter the Lunae Planum area.  One of the first features we come to in southeast is the Ganges Catena at 3°S 290° E.

Ganges Catena Pit Crater Chain Cut by Wrinkle Ridge

Going south of the Ganges Catena we come to Ceti Chasma.  One of the smallest Chasma thus far encountered.  Ceti Chasma is located at 5° S 292° E.

Layers in Ceti Chasma

In about the center of Lunae Planum we find Dittaino Valles a channel probably originating in the Ganges Catena area whose outflow is to the north into the next Region.

Dittaino Valles at 1°S  293°E.

The western border of Lunae Planum in the Coprates Region can be said to be the Juventae Chasma whose center is at about 3° S 299° E.

Juventae Chasma

Juventae Chasma is an enormous box canyon (250 km × 100 km) on Mars which opens to the north and forms the outflow channel Maja Valles.

Image of Juventae Chasma DTM

Juventae Chasma is located north of Valles Marineris and cuts more than 5 km into the plains of Lunae Planum. The floor of Juventae Chasma is partly covered by sand dunes. There is also a 2.5 km high mountain inside Juventae, 59 km long and 23 km wide, that was confirmed by Mars Express to be composed of sulfate deposits. MRO discovered sulfates, hydrated sulfates, and iron oxides in Juventae Chasma.

 

To the north of Juventae Chasma is Baetis Chaos located at 1°S 300° E.  It is 55 km in diameter.

Baetis Chaos Close Up

Continuing east from Baetis Chaos we enter the Xanthe Terra Area. It extends all the way to the eastern border of the Coprates Region.  In it at about 305°E we come across the bottom half of the Mutch Crater on the Equator.  This Crater is 211 km in diameter.

Central Uplift of Mutch Crater

In the northeast corner of the Coprates Regions lies Orson Wells Crater 0° 315° E.

Orson Welles Crater, as seen by HiRISE. Layered, light-toned rocks seem to be under a dark mantling material. Layers may be sandstone, volcanic ash, or lakebed deposits.

Orson Welles Crater: is an impact crater in the Coprates Region of Mars, located at 0.2° S and 315° E. It is 124.5 km in diameter and was named after Orson Welles, an American radio and motion picture actor and director (1915–1985). He is famous for, among other things, his radio broadcast of The War of the Worlds in which Martians invade Earth.

Now the Survey will head back west to the other side of the Coprates Region between 5-10 °S :

Ganges Chasma, as seen by Themis. The location is 6.4 degrees south latitude and 310.7 degrees east longitude. Image is about 18 km wide.

Ganges Chasma is a deep canyon at the eastern end of the vast Valles Marineris system on Mars, an offshoot of Capri Chasma. It is named after the River Ganges in South Asia. Ganges Chasma is thought to have formed through a series of catastrophic discharges of water and CO2 from chaos terrains such as that preserved in Ganges Chaos at its southern margin. Most of the evidence for these discharges and the ensuing collapses is believed to have been washed away. Prior to developing an outlet that joined it to Capri Chasma and the connected outflow channels to its east, Ganges Chasma may at some point in the Noachian period have contained a lake which drained northward through partially subsurface pathways into the Shalbatana Vallis.

Ganges Chasma Layers, as seen by HiRISE. Location is 8.1 degrees south latitude and 307.5 degrees east longitude. Image was taken by the Mars Reconnaissance Orbiter's HiRISE.

Images of rocks in the canyon walls almost always show layers. Some layers appear tougher than others. In the image  of the  Ganges Chasma Layers, as seen by HiRISE, one can see that the upper, light-toned deposits are eroding much faster than the lower darker layers. Some cliffs on Mars show a few darker layers standing out and often breaking into large pieces; these are thought to be hard volcanic rock instead of soft ash deposits.  Because of its closeness to the Tharsis volcanic region, the rock layers may be made of layer after layer of lava flows, probably mixed with deposits of volcanic ash that fell out of the air following big eruptions.

Close-up of layers in wall of Valles Marineri

It is likely the rock strata in the walls preserve a long geological history of Mars. Dark layers may be due to dark lava flows. The dark volcanic rock basalt is common on Mars. However, light-toned deposits may have resulted from rivers, lakes, volcanic ash, or wind blown deposits of sand or dust. The Mars Rovers found light-toned rocks to contain sulfates. Probably having been formed in water, sulfate deposits are of great interest to scientists because they may contain traces of ancient life.

Light Toned Mounds in Ganges Chasma DTM

The HiRISE DTMs are made from two images of the same area on the ground, taken from different look angles. Not all of these images have been made into DTMs due to the time-intensive process. Creating a DTM is complicated and involves sophisticated software and a lot of time, both computing time and human operator time.  The great advantage of a HiRISE DTM is the high resolution of the source images.

Elaver Vallis and Vicinity

From the southern canyon of  Ganges Chasma we come to the Elaver Vallis.  This valley is 160 km long and named for the Allier River in France.

 

To the west is Morella Crater located 9.7°S 308°E. it is 79 km in diameter.

Morella Crater is the large crater in center of Picture

Morella crater is named after a place name in Spain.  As we head back west we enter an area called the Ophir Planum, which forms the northern border of Valles Marineris Canyons and a central plateau area between Ganges Chasma in the east and the Valles Mariners Canyons to the west.  Heading west between 5-10° S we come into the Ophir Catenae located at 9.5°S 300.6°E.  It stretches all the way to Candor Chasma.

Fresh 5-Kilometer Diameter Crater Near Ophir Catenae

In planetary geology, a catena is a chain of similarly sized craters. On Mars, they are named after nearby classical albedo features as prescribed by the International   Astronomical Union's rules for planetary nomenclature. While catenae on most bodies of the Solar System consist of mainly of impact craters, those on Mars consist primarily of collapse pits.

Just north of Ophir Catenae at 7° 298° E is Hydrae Chasma which is a small Chasma.

Bedrock in Hydrae Chasma

Hydrae Chasma is a deep, circular depression covering and area of about 50 kilometers.

 

Just southwest of Hydrae Chasma at 8° S 296 E. begins Candor Chasma.

Image: Ridges as Evidence of Fluid Alteration on the Planet Mars. Tectonic fractures within the Candor Chasma region of Valles Marineris, Mars, retain ridge-like shapes as the surrounding bedrock erodes away. This points to past episodes of fluid alteration along the fractures and reveals clues into past fluid flow and geochemical conditions below the surface.

Layers and Canyons in Candor Chasma

Candor Chasma is one of the largest canyons in the Valles Marineris canyon system on Mars. The feature is geographically divided into two halves: East and West Candor Chasmata, respectively. It is unclear how the canyon originally formed; one theory is that it was expanded and deepened by tectonic processes similar to a graben, while another suggests that it was formed by subsurface water erosion similar to a karst (a karst is a region, that includes underground streams, sinks, ravines, and gorges). MRO discovered sulfates, hydrated sulfates, and iron oxides in Candor Chasma.

 

Going a little more than halfway through  Candor Chasma we come to the canyon wall of the Baetis Mensa at about 5.5°S 288 E.

Dark Spots on the West Side of Baetis Mensa

To the south of the Baetis Mensa we come to the Candor Mensa at 7°S 286.5 E. 

The Candor Mensa

If one goes east at this point the Candor Chasma ends at 283°E.  But if we continue south we pass through the Candor Chaos to enter the Melas Chasma.   The Candor Chaos is located at 7°S 287 E.

Chaos on the Floor of Candor Chasma

Central and Western Melas Chasma

Melas Chasma is a canyon on Mars, the widest segment of the Valles Marineris canyon system, located east of Ius Chasma at 9.8°S, 283.6°E. It cuts through layered deposits that are thought to be sediments from an old lake that resulted from runoff of the valley networks to the west. Other theories include windblown sediment deposits and volcanic ash. Support for abundant, past water in Melas Chasma is the discovery by MRO of hydrated sulfates. In addition, sulfate and iron oxides were found by the same satellite  on the floor of Melas Chasma is about 70% younger massive material that is thought to be volcanic ash whipped up by the wind into Aeolian features. It also contains rough floor material from the erosion of the canyon walls.

 

Ius Chasma is a large canyon in the Coprates Region of Mars at 7° south latitude and 85.8° west longitude. It is about 938 km long and was named after a classical albedo feature name.

Ius Chasma faults and floor

Ius Chasma is believed to have been shaped by a process called sapping when water seeped from the layers of the cliffs and evaporated before it reached the canyon floor. Ius Chasma also has several structural features such as east trending normal faults and grabens that deformed the canyons. Recent geomorphologic events include avalanches and minor sapping from gullies that continued to erode the canyon walls.  Because of its closeness to the Tharsis volcanic region, the rock layers may be made of layer after layer of lava flows, probably mixed with deposits of volcanic ash that fell out of the air following big eruptions. Dark layers may be due to dark lava flows, however, light-toned deposits may have resulted from rivers, lakes, volcanic ash, or wind blown deposits of sand or dust. The Mars Rovers found light-toned rocks to contain sulfates.

To the south of Ius Chasma is a group of Valles called Louros Valles. These Valles are located between 274°E and 282°E and between 10-7°S.

 

^{Light-Toned Material in Western Louros Valles/Sinai Planum}

 

The Louros Valles are 517 km in length and named after the Louros River in northwestern Greece.

 

At the western end of the Ius Chasma we come to the Calydon Fossa located at 270°E  7.5°S.

Calydon Fossa

 

The Calydon Fossa is 351 km in area. Named after  the Calydon  son of Ares and Astynome.

Small Pale Red Planet Issue 3 Phase 2

 

Phoenicis Lacus Region

MC-17

 

The Phoenicis Lacus Region covers the area from 90° to 135° west longitude and 0° to 30° south latitude on Mars. The Tharsis rise, which was formed from lava flows, occupies part of area. The volcanoes Pavonis Mons and Arsia Mons are believed to have once had glaciers on them. Glaciers may still exist under a thin layer of rocks.

 

 

Topographical Map of the Phoenicis Lacus Region

The ice on Mars can be a source of water for the possible future colonization of the planet. One of the most prominent features of this quadrangle is a large intersecting set of canyons called Noctis Labyrinthus. Other interesting features are lava channels, Dark slope streaks, pit crater chains, and large troughs (called fossae). Research published in the journal Icarus has found pits in Zumba Crater are caused by hot ejecta falling on ground containing ice. The pits are formed by heat forming steam that rushes out from groups of pits simultaneously, thereby blowing away from the pit ejecta.

Image of the Phoenicis Lacus Region

Starting in the northeast corner of the Phoenicis Lacus Region we encounter a crater cluster  which lies near the equator 510 miles south of Olympus Mons, in a type of terrain called the Medusae Fossae formation. The formation is coated with dust and contains wind-carved ridges called yardangs. These yardangs have steep slopes thickly covered with dust, so when the sonic boom of the air blast arrived from the impacts caused by meteoritess, dust started to move down the slope. Using photos from Mars Global Surveyor and HiRISE camera on NASA’s Mars Reconnaissance Orbiter, scientists have found about 20 new impacts each year on Mars. Because the spacecraft have been imaging Mars almost continuously for a span of 14 years, newer images with suspected recent craters can be compared to older images to determine when the craters were formed. Since the craters were spotted in a HiRISE image from February 2006, but were not present in a Mars Global Surveyor image taken in May 2004, the impact occurred in that time frame.

This image indicates a crater cluster and curved lines formed by air blast from meteorites.

Meteorites caused the air blast which caused dust avalanches on steep slopes. Image is from HiRISE.

Close up of previous image along light/dark boundary. Dark line in middle of image shows border between light and dark area of curved lines.

Green arrows show high areas of ridges. Loose dust moved down steep slopes when it felt the air blast from meteorite strikes. Image is from HiRISE.  Location is of this image is 0 latitude and 226.9 E

Going southeast of this location to 5°S 230°E we come to the Arisa Sulci.

Arisa Sulci as seen by Themis

Sulci is a term used for sub parallel furrows and ridges in Mars geography, it was given the name Arisa because of its close proximity to the volcano Arisa Mons.

By going southward at 230°E we enter the Daedalia Planum which continues from the last Region we were in to the west.  The Daedalia Planum covers the southwest quarter of the Phoenicis Lacus Region.

Unusual Surface Structure in Daedalia Planum at 21°S 223°E

South of there at we come to Zumba Crater.  Zumba Crater, as seen by HiRISE. The  location is 28.7 South and 226.9 East.

Zumba Crater

Close up examination of Zumba Crater (Vis/Ani)

Zumba Crater is only 3.3 km in diameter and was named after a town in Ecuador.  Zumba has a depth of about 620 meters, and its rim rises about 200 meters above the surrounding lava-filled plains of Daedalia Planum. Zumba is approximately 25% deeper than the average Martian crater of this size, this fact suggests it is a very fresh crater.  Since Zumba is so young, it is a perfect example of a simple crater. On Mars, a simple crater is generally less than 6-9 km in diameter with a conical-bowl shape, little wall collapse, and it lacks a well-developed central feature, like a central peak.  Zumba is of special interest to scientists, because it possesses interesting features that are typically buried or eroded away in other older Martian craters, and even within the freshest terrestrial craters, including Meteor crater in Arizona. These preserved and newly recognized features observed at the scale of HiRISE may reveal new aspects of the impact process.  A pitted deposit giving Zumba the appearance that it has a relatively flat floor despite the pits is especially interesting. These crater-fill deposits are typically composed of lightly to highly damaged rock fragments and impact melts that were made by the high temperatures of the impact event. The pits in the crater-fill deposits have not been observed within lunar or terrestrial craters. They are unique to crater-fill deposits in only the freshest and best-preserved Martian craters.  These pits may result from the interactions of hot crater-fill deposits with water and water-ice that may have been present in the subsurface prior to impact. It is not well understood whether these pits form explosively (similar to terrestrial volcanic pits/craters formed from the interaction of hot lava with wet sediments/deposits), or by collapse from the drainage of impact melts or volatiles. Since the pitted deposits occur only in the freshest and well-preserved craters suggests that they are likely related to the impact process.

Traveling back north we pass through the Daedalia Planum again.

Large Pit Crater in Daedalia Planum at 19.5°S 237°E.

At 11°S 234°E we come to Aganippe Fossa.

Aganippe Fossa Surface Texture Sample

Aganippe Fossa is a surface feature on Mars which runs from 4.1° to 13° south latitude and 233° to 235° east longitude. It is named after a classical albedo feature. Its name was approved by the IAU in 1976. There are dark streaks on the slopes of Aganippe Fossa. Such streaks are common on Mars. They occur on steep slopes of craters, troughs, and valleys. The streaks are dark at first. They get lighter with age. Sometimes they start in a tiny spot, then spread out and go for hundreds of meters. They have been seen to travel around obstacles, like boulders. It is believed that they are avalanches of bright dust that expose a darker underlying layer. However, several ideas have been advanced to explain them. Some involve water or even the growth of organisms. The streaks appear in areas covered with dust. Much of the Martian surface is covered with dust. Fine dust settles out of the atmosphere covering everything.

At about 3.6°S 233°E we come to a new impact crater directly north of the Aganippe Fossa.

New Impact crater formed between March 2000 and July 2003, as seen by HiRISE.  Scale bar is 500 meters long.

On the northeastern side of Arisa Mons we come to the Arisa Chasmata.

Arsia Chasmata, as seen by HiRISE. Location is 7.8 degrees south latitude and 240.7 degrees east longitude. Image was taken by the Mars Reconnaissance Orbiter's HiRISE.

Arsia Chasmata: is a steep-sided depression in the Phoenicis Lacus Region on Mars, located at 7.6° S and 241° E. It is 81 km long and was named after an albedo name.  It has pit craters that must have formed when a void is produced by a cracking of the surface caused by stretching. Also, lava may drain out of an underground chamber, thus leaving an empty space. When material slides into a void, a pit crater or a pit crater chain forms. Pit craters do not have rims or ejecta around them, like impact craters do. On Mars, individual pit craters can join to form chains or even to form troughs that are sometimes scalloped.

Next we come to the largest volcano in the Phoenicis Lacus Region the Arisa Mons.

 

Topographical Map of the Arisa Mons and surrounding area.

Arsia Mons is the southernmost of three volcanos (collectively known as Tharsis Montes) 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 mountain 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 Arisa Mons (2 views)

The Location of Arisa Mons is 8.35°S 240.5°E.  Arsia Mons is a shield volcano with a relatively low slope and a massive caldera at its summit. The southernmost of the three Tharsis Montes volcanoes, it is the only major Tharsis volcano south of the equator.  The volcano is 435 kilometers (270 mi) in diameter, almost 20 kilometers (12 miles) high (more than 9 kilometers (5.6 mi) higher than the surrounding plains), and the summit caldera is 72 miles (approximately 110 km) wide. It experiences atmospheric pressure lower than 107 pascals at the summit. Except for Olympus Mons, it is the biggest volcano in volume. Arsia Mons has 30 times the volume of Mauna Loa in Hawaii, the largest volcano on the Earth.

Area Near Arisa Mons

South of Arisa Chasmata on the southern rim of Arisa Mons we come to Oti Fossae.  Oti Fossae is a trough in the Phoenicis Lacus Region on Mars, located at 9.3° S and 242° E.

Close-up of Oti Fossae, parallel graben, as seen by Themis. Location is 8.1 S and 243.8 E. Image is 18.1 km wide.

Oti Fossae, as seen by THEMIS. has  parallel graben  found on the northeastern side of Arsia Mons; they are in line with the NE/SW trend of the three volcanoes in Tharsis.

THEMIS image of probable cave entrances on Arsia Mons. The pits have been informally named (A) Dena, (B) Chloe, (C) Wendy, (D) Annie, (E) Abby (left) and Nikki, and (F) Jeanne.

The Caves of Mars Program also studied designs for inflatable modules and other such structures that would aid the astronauts to build a livable environment for humans and earth creatures.  As of 2007 seven putative cave entrances, have been identified in satellite imagery of the flanks of Arsia Mons. They have been informally dubbed Dena, Chloe, Wendy, Annie, Abbey, Nikki, and Jeanne and resemble "skylights" formed by the collapse of lava tube ceilings: 
1’Dena (6.084°S 239.061°E)
2.Chloe (4.296°S 239.193°E)
3.Wendy (8.099°S 240.242°E)
4.Annie (6.267°S 240.005°E)
5 & 6 Abbey and Nikki (8.498°S 240.349°E)
7.Jeanne (5.636°S 241.259°E)
From day to night, temperatures of the circular features change only about one-third as much as the change in temperature of surrounding ground. While this is more variable than large caves on Earth, it is consistent with them being deep pits. However, due to the extreme altitude, it is unlikely, so some think, that they will be able to harbor any form of Martian life.  A more recent photograph of one of the features shows sunlight illuminating a side wall, suggesting that it may simply be a vertical pit rather than an entrance to a larger underground space. Nonetheless, the darkness of this feature implies that it must be at least 178 meters deep, and that is deep enough to harbor life.

Possible cave entrance to ("Jeanne") on Arsia Mons

Dark pits on some of the Martian volcanoes have been speculated to be entrances into caves. A previous HiRISE image, looking essentially straight down, saw only darkness in this pit.  This time the pit was imaged from the west. Since the picture was taken at about 2:30 p.m. local (Mars) time, the sun was also shining from the west. We can now see the eastern wall of the pit catching the sunlight.  This confirms that this pit is essentially a vertical shaft cut through the lava flows on the flank of the volcano. Such pits form on similar volcanoes in Hawaii and are called "pit craters." They generally do not connect to long open caverns but are the result of deep underground collapse. From the shadow of the rim cast onto the wall of the pit we can calculate that the pit is at least 178 meters (584 feet) deep. The pit is 150 x 157 meters (492 x 515 feet) across.

A repeated weather phenomenon occurs each year near the start of southern winter over Arsia Mons. Just before southern winter begins, sunlight warms the air on the slopes of the volcanos. This air rises, bringing small amounts of dust with it. Eventually the rising air converges over the volcano's caldera and the fine sediment blown up from the volcano's slopes coalesces into a spiraling cloud of dust that is thick enough to observe from orbit. The spiral dust cloud over Arsia Mons repeats each year, but observations and computer calculations indicate it can only form during a short period of time each year. Similar spiral clouds have not been seen over the other large Tharsis volcanoes, but other types of clouds have been seen. The spiral dust cloud over Arsia Mons can tower 15 to 30 kilometers (9.3 to 19 mi) above the volcano.

Orographic water ice clouds hover over the volcanic peaks of the central Tharsis region in this color image mosaic from Mars Global Surveyor. Olympus Mons dominates at upper left. At center are the three Tharsis Montes: Arsia Mons at bottom, Pavonis Mons at center, and Ascraeus Mons at top. (Orographic: any cloud whose existence and form are largely controlled by the disturbed flow of air over and around mountains).

The volcanoes of the Tharsis region are highlighted by this color image mosaic obtained on a single Martian afternoon by the Mars Orbiter Camera (MOC) onboard the Mars Global Surveyor (MGS) spacecraft. Olympus Mons dominates the upper left corner -- it is one of the largest known volcanoes and is nearly 550 km (340 miles) wide. The gray scale image on the right shows the name of each volcano in the scene.  The white or bluish-white features are clouds. Clouds are common over the larger Tharsis volcanoes in mid-afternoon. The four largest volcanoes are more than 15 km (9 mi) high. Viewed from Earth by telescope before any spacecraft had visited the planet, astronomers often described a "W"-shaped white cloud over the Tharsis region. This "W" was actually the result of seeing the combined effects of bright clouds hanging over the Ascraeus, Pavonis, Arsia, and Olympus volcanoes. The clouds result when warm air containing water vapor rises up the slopes of each volcano, cools at the higher altitude, and causes the water vapor to freeze and form a cloud of ice crystals.  Pavonis Mons lies on the Martian equator, north is up, and sunlight is illuminating the scene from the left. The picture is a mosaic of red and blue filter images taken on three consecutive orbits. The slightly blurred appearance of the left side of Arsia Mons results from distortion toward the edges of the images used to make the mosaic. To remove the blur, an image obtained on another day would be added to the mosaic--however, this image would not match well because the cloud patterns will have changed by the next day. Mosaics such as the one shown here are used to monitor changes in Martian weather and to plan future observations.

Going to 2.5°S 246°E we come to the southern part of the Pavonis Mons volcano. Here too we find caves that are the result of  lava tubes.

Lava Tubes of Pavonis Mons

Lava sometimes forms a tube as it moves away from the vent (opening from which lava flows from a volcano). The top of a stream of lava cools down, thereby forming a solid roof. Meanwhile, the lava continues moving in the tube. Often, when all the lava leaves the tube, the roof collapses, making a channel.  These  features are found on Mars. Some can be seen around Pavonis Mons, in the picture above.  . Some people have suggested that future colonists on Mars could use lava tunnels as shelters. They would offer great protection from radiation, especially ultraviolet radiation. Lava Channels on the flank of the volcano Pavonis Mons are pictured below in a picture from Mars Odyssey THEMIS. Sometimes the lava tube remains intact for a time. Lava will break out along the tube to accumulate or flow away. Lava flows often have a lobate appearance at the edges. A good view of such a lava tubes is shown above.

Many of the volcanoes on Mars show strong evidence of past and possible present glacial activity. When glaciers melt and retreat, they leave behind material that was carried in and on the ice. Often the material is dropped in a ridge, called a moraine.

 

Ridges on side of Arsia Mons, a large volcano, may be moraines dropped by glacial activity.

Underground Habitat on Mars

Passing out of the Tharsis Montes area we go south and re-enter the Daedalia Planum.

Pit in Lava Flows in Daedalia Planum at 18°S 243°E

Then heading east we come Claritas Rupes area which is  a mountain ridge running from south to north.  Here we come across the Lenya and Tecolate Craters.

Lenya and Tecolate Craters

Lenya Crater is 15.5 km in diameter and is named after a Burma place name. Tecolate Crater is 51 km in diameter and is named after a place in New Mexico USA. 

Claritas Rupes Area

Claritas Rupes is a scarp in the Phoenicis Lacus Region of Mars, located at 26° South and 255°East.  It is 924 km long and was named after an albedo feature at 25°S, 250°E

After this we come to another long group of troughs and graben the Claritas Fossae.  Claritas Fossae is a group of troughs in the Phoenicis Lacus and Thaumasia Regions of Mars, located at 31.5° S and 254°E.

 

Claritas Fossae  Note the steep scarp.

Claritas Fossae:  Note the steep scarp.

The structure is 2,050 km long and was named after a classical albedo feature name.  Long narrow depressions on Mars are called fossae. 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. Fossae/pit craters are common near volcanoes in the Tharsis and Elysium regions. 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.

As we head north we enter the Syria Planum.  It covers a large area from 8-20°S and 250-260°E at its widest extent.

Syria Planum

In the center of Syria Planum is the Syria Mons at 256°E 12°S.

Identification of Syria Mons in Syria Planum by Themis

Syria Planum is found between 8°-20°S and 110°-95°W. It is bound by Noctis Labyrinthus to the north and to the south by Claritas Fossae and Solis Planum. Syria Planum has long been acknowledged as a volcanic and tectonic center within the Tharsis province. Data from Mars Orbiter Laser Altimeter (MOLA) showed that the plateau is composed of dozens of small, coalesced shield volcanoes.   Recently a geologic history was proposed for Syria Planum including multiple volcanic and tectonic events. A theory was developed as a geologic history of Syria Planum including tectonic and volcanic events identified in the Plateau. First, Northwest trending Noachian aged graben formed in the existing basement rock. These were enclosed by Hesperian lavas from Syria Mons, located near the center of the plateau. The lavas from the volcano flowed up to 1000 km to the southeast, covering a very large aerial extent. Sparse northeast trending faults later altered the volcano. To the east of Syria Mons, a second volcanic episode produced dozens of Hesperian aged volcanic vents whose flows  coalesced to form a monogenetic volcanic field. Each shield covers an aerial extent of <1500 km2. These volcanoes are unabated to the southwest where some of their lava flows encircled the older flows of Syria Mons to the west. Finally, possibly during the opening of Noctis Labyrinthus, large scale (10s of kilometers in length) collapse features with a wide range of orientations formed within both volcanic units.   Images from the Thermal Emission Imaging System (THEMIS), the Context Imager (CTX), and the High Resolution Imaging Science Experiment (HiRISE) as well as MOLA altimetry data were used to identify locations where lava erupted onto the surface of Syria Planum, forming small (up to 10s km in diameter) volcanic vents.

The Noctis Labyrinthus is a large canyon system found in the Phoenicis Lacus Region just north of the Syria Planum. Its walls contain many layers of rocks. Research, described in December 2009, found a variety of minerals—including clays, sulfates, and hydrated silicas in some of the layers.  Noctis Labyrinthus, "the labyrinth of the night", is a region of Mars between Valles Marineris and the Tharsis upland.  It is located in the Phoenicis Lacus Region. 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.

Mariner 9’s image of the eastern part of the Noctis Labyrinthus near the western end of the Valles  Marineris on Mars.

Linear graben, grooves, and crater chains dominate this region, along with a number of flat-topped mesas. The image is roughly 400 km across, centered at 6° S, 255°E, at the edge of the Tharsis bulge.  Layers in the walls of Noctis Labyrinthus were discovered with Mars Global Surveyor,under the MOC Public Targeting Program.

Newer Image of Noctis Labyrinthus Canyon System

Ground view of the Canyons of Noctis Labyrinthus

This video shows the Noctis Labyrinthus features in more detail taken by MRO and Themis. 

To the north of Noctis Labyrinthus is the Noctis Fossae at 5°S 260°E.  It stretches all the way to the northern border of the Phoenicis Lacus Region.

Trough in Noctis Fossae

Going to the southeast from there we come to the western edge of the Valles Marineris at 5°S 265°E.  Valles Marineris (Latin for Mariner Valleys, named after the Mariner 9 Mars orbiter of 1971–72 which discovered it) is a system of canyons that runs along the Martian surface east of the Tharsis region. At more than 4,000 km (2,500 mi) long, 200 km (120 mi) wide and up to 7 km (23,000 ft) deep, the Valles Marineris rift system is one of the larger canyons of the Solar System, surpassed only by the rift valleys of Earth and (in length only) by Baltis Vallis on Venus.  Valles Marineris is located along the equator of Mars, on the east side of the Tharsis Bulge, and stretches for nearly a quarter of the planet’s circumference. The Valles Marineris system starts to it’s west with Noctis Labyrinthus.

Valles Marineris in mosaic of THEMIS infrared images from 2001 Mars Odyssey

The Noctis Labyrinthus, on the western edge of the Valles Marineris Rift System, north of the Syria Planum and east of Pavonis Mons, is a jumbled terrain composed of huge blocks which are heavily fractured. Also it contains canyons that run in different directions surrounding large blocks of older terrain. Most of the upper parts of the blocks are composed of younger fractured material thought to be of volcanic origin associated with the Tharsis bulge. The other tops are composed of older fractured material thought also to be volcanic in origin, but differentiated from the younger material by more ruggedness and more impact craters. The sides of the blocks are composed of undivided material thought to be basement rock. The space between the blocks is composed mainly of either rough or smooth floor material. The rough floor material tends to be in the eastern portion of the Noctis Labyrinthus and is thought to be debris from the walls or maybe Aeolian features covering rough topography and landslides. The smooth floor material is thought to be composed of fluvial material and/or Aeolian features covering an otherwise rough and jumbled terrain. Terrains such as Noctis Labyrinthus are commonly found at the head of outflow channels, like the one explored by the Pathfinder mission and its Sojourner rover. They are interpreted to be a place of downward block faulting associated with the removal of ground fluid in catastrophic flood sequences. The fluid could be either carbon-dioxide ice and gas or water. Water is the prevailing theory, but one scientist proposes carbon dioxide gas/liquid as an agent of flooding.

Both the Tithonium Chasma and Ius Chasma extend eastward from the Noctis Labyrinthus into the main area of the Valles Marineris Canyon.

Northwest Ius Chasma

Crossing the Ius Chasma to the southeast we come to  Oudemans Crater at 10°S  268°E.  Oudemans Crater is an example of very pristine morphology since small features in its ejecta and on its floor are preserved. Being young, it does not display water erosion on its rim. Unlike some craters, Oudemans Crater does not have alluvial fans on its floor. In places, its rim has a terrace. 

 

Layers in Oudemans Crater Wall, as seen by HiRISE. You can see many fine layers in walls of this crater.

Its location puts it near the intersection of Noctis Labyrinthus and the Ius Chasma of the Valles Marineris rift system. It is approximately 90 km wide, indicating it was caused by a meteorite 4.5 km in diameter. Nick Hoffman proposes that this might be the trigger that caused the formation of the flow deposits on the east end of the Valles Marineris System. He proposes that the impact heated up subsurface carbon dioxide permafrost causing explosive decompression that flooded down the Valles Marineris into the Northern Plains of Mars. The central uplift of Oudemans Crater exposes layered rock that may be sedimentary. Layered rock exposed in the central uplifts are common in terrestrial impact structures, and there is abundant layering exposed in the nearby Valles Marineris canyon system suggesting that layered deposits extend throughout the region.  Oudemans Crater was named after Jean Abraham Chrétien Oudemans (Amsterdam, December 16, 1827 - Utrecht, December 14, 1906) he was a Dutch astronomer. He was the director of the Utrecht Observatory from 1875 until 1898, when he retired.

Going south from there we enter the Sinai Planum at 9°S 267°E. It is a plateau region that covers 900 km in area.

Plains in Sinai Planum

The Syria Planum is shown to be a composite, asymmetric crater formed by impact of at least two bolides whereas Sinai Planum is interpreted to be a result of a chain of tightly-clustered impacts , perhaps partly the result of spelled projectiles. The impact complex is portrayed  as having tectonic elements including a a circumferential crustal welt, compressional crustal wedging, and an extensional regime having embedded volcanic activity including Olympus Mons and Tharsis Montes. The craters lie in the center of the crustal welt having about 135 degree surface span.  Syria Planum and Sinai Planum lie at the center of a complex crustal structure interpreted to be the result of a multiple, hypervelocity (>6km/sec) impact event on Mars. Syria Planum is shown to be a composite, asymmetric crater formed by impact of at least two bolides whereas Sinai Planum is interpreted to be a result of a chain of tightly-clustered impacts , perhaps partly the result of chipped or split projectiles. The impact complex is portrayed as having tectonic elements including a a circumferential crustal welt, compressional crustal wedging, and an extensional regime having embedded volcanic activity including Olympus Mons and Tharsis Montes.

Crater Wall in Solis Planum

This dramatic perspective view looks south-east along the wall of a large eroded impact crater in the Solis Planum, bordering the mountainous Thaumasia region of Mars. Stretching for about 50 kilometers into the scene, the crater wall is around 800 meters high. Located just south and west of the Red Planet's grand Valles Marineris, this area features mountains and fault lines that are seen as evidence of surface plate motions or plate tectonics. The process of plate tectonics has long been shaping the surface of planet Earth but is thought to have been only briefly active on Mars. The image was constructed using color image data from the High Resolution Stereo Camera onboard ESA's Mars Express spacecraft.  The Solis Planum extends all the way to the southern border of the Phoenicis Lacus Region.