Реферат: Geology Fo Mars Essay Research Paper Geology
Geology Fo Mars Essay, Research Paper
Geology of Mars
by Luke Justis
Mars is the planet that is the closest geologically to our own. Still we know little about the planet. All the information that we have is from what we see. We can speculate about the geology of the planet but we will never know for sure what the planet is really made of until we physicallygo there. The information is all from NASA sites or NASA related sites.
Mars red color leads us to believe that the planet has large amounts of iron. This red color is the only color that is on the surface besides the poles. There is also a darker area that runs along the equator. It goes around roughly one third of the planet. This is a giant canyon that makes our Grand Canyon look like a scratch. There are also what appear to be old stream channels. This implies that there could have been liquid water on the surface.
The surface of Mars is varied greatly between north and south. This has been largely attributed to volcanism and erosion. Mars is similar to our moon in the southern hemisphere. This region is referred to as the Highlands of Mars. The area is pitted with numerous craters that reach between one to four km above the datum. Ejecta from the impact scatter around the crater making a rim like structure.
The northern hemisphere is very low compared to the southern hemisphere. In the north the ground level rarely reaches above one km below the datum. This stark contrast between north and south is thought to have happened 3 Gyr ago. The south was continuously bombarded with meteors. The north would get hit but it would erode or volcanic flows would cover it. The north also has evidence of ancient stream channels and at the extreme north and south glaciers are still present in the form of an ice cap.
The region known as Tharsis is at the center of a bulge in the planets surface. This giant volcano is 4000 km across and 10 km high. Another bulge is called Elysium and it is about 2000 km across and 5 km high. At the summit of Tharsis are three volcanoes the tallest of these is Olympus Mons. The peak of this volcano is 27 km above the place where Tharsis ends and Olympus Mons begins.
The volcano itself was made by periodic eruption over a period of time. The lava is most likely very fluid and would have little pyroclastic activity. The large size of the volcano can be attributed the lack of tectonic activity. Few impact craters on the flank of the volcano suggest that the volcano is relatively young. It is possible though, that volcanism could have been occurring during much of Mars history.
Mars volcanoes are very similar to those found on Earth specially those found on Hawaii. Their low shape and large flows are very similar to those in Hawaii. Ash deposits are also very common on Martian volcanoes. Evidence for hydrothermal activity is also another commonly found geologic feature on Mars suggesting even more that there is water on Mars.
The role of water erosion is the most mysterious this geologically about Mars. Large dry valleys and evidence Of ancient flood plains all add to the mystery. Old shore lines in the North suggest that there could have been huge lakes caused by massive floods. The floods could have been caused by the heating of the surface or a change of climate. All these bits and pieces add to the debate of whether or not Mars had large amounts of water like Earth at one time or another.
The rate at which the water did carve the stream channels and large valleys is still uncertain. There is supple evidence to suggest that the water ran at a slow pace. The features of these valleys appear to be the product of slow erosion. Branch valley networks are commonly found in the southern hemisphere and some in younger areas. The channels appear to have tributaries that increase the size of the main stream channel. This is still heavily debated because the inside of the valleys is rarely seen, so channels have observed on a few occasions. The valleys carved are short compared to those found on Earth, some under a hundred km. There probably was not a large drainage system like the Mississippi on Mars. The most logical explanation for this is slow water erosion. The most puzzling thing about these river systems is the way some of them end. There are some that just end. A possible explanation for this is ground water sapping. And still other look as though they were cut out by surface run off. All these water features make Mars more intriguing.
Although there are no massive tectonic plates like those found on e
Earth there, is still activity in the lithosphere. Along the edge of Tharsis, the immense pressure produced by the volcano cause radial garbens. Tharsis causes faulting along the entire area affected by it but also the entire planet. The faults produced by Tharsis travel along the planet’s surface producing canyons. These canyons eventually meet up with each other and make the massive canyon mentioned earlier. This canyon also has its own type of faulting. There are sheer cliffs that drop down several kilometers. There are several areas with evidence of fault scarps. Deep gullies carved on the side of the canyon lead us to believe that there was once water erosion at one time creating a temporary lake.
The ice on the poles is the most obvious feature on the planet. Mars ice is relatively young compared to the rest of the planet. The ice is a very recent event in the Martian history. Still the ice could be a few million years old. Mars ice is basically a recording of the events that occurred on Mars over the last couple of million years.
Sandstorms on Mars leave deposits on the surface of the ice during periods of melting. The ice then refreezes and records that event. This could give us an idea of how old the ice is or what type of cycle the sandstorms run on. The ice also give us an idea of what type of cycle the planets is on. There are summers and winters on Mars. This is another way that the age of the ice could be figured. Ice also tells a little about what type of climate Mars has. If it was an extremely hot planet like Venus then the ice would not exist. The ice itself is most likely just like what we have on Earth. It is deposited in layer and is generally smooth with few impact craters. Most of the time the ice is covered with a frost of frozen Co2. In the summer the ice partly defrosts and this allows the layering to happen. The deposits are thought to be composed primarily of dust and ice. The layering indicates that the deposits are in some sort of a cycle.
Ground ice only occurs at extreme lows or at very high altitudes. Water vapor cannot escape fast enough so it becomes ice deposits on the ground. This also happens around the edge of craters suggesting the possibility of ground water. Little is known about the ice in deep canyons but it is assumed that there is deposits of ice at the extreme lows.
Mars is still geologically a mystery to us. It has features that are very similar to Earth s, but there are some that are unique to Mars. We cannot start to understand the complexity of mars geology until we can actually land there. Then the red planet will start to revel it secrets to us.
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