Craters

Mars is a planet of great geological difference. The north has a fiery volcanic past and the south has a cratered scared past. One of the greatest features on Mars is its impact basins in the south. Some impact basins hold huge craters, some of which may have caused catastrophic effects on the whole ecosystem. One of the biggest impact basins on Mars is Hellas Planatia. From orbit it seems to be just an enormous dark spot but new mapping techniques have discovered it is actually an ancient crater. It is possible that this asteroid may have kicked up enough dust to blanket the planet's atmosphere and kill whatever lived there. Was this Mars' rocky ending? This image on the left is a computer generated image of a small section of the Hellas Basin. It shows the diversity of the landscape. In some areas there are flat planes for miles and in others there are sharp cliffs jutting into the sky.

Wet Craters

In this picture you can see that all of the land around these craters remains undisturbed and uneroded. This is because that soil has been strongly compacted and it is harder to be carried away by flowing water. These craters and the ones in the upper right hand side are pretty good examples of wet craters. They are called wet craters or splash craters because when they land and spew out ejecta. Wet soil acts differently than dry soil. So you get the rock in the mud example....which is (experiment time!!!) when you throw a rock in some mud you will get a splash effect where the rim of the crater is not a crisp ring it is more a soft and it would have globs around the outside.

Here is another example of a wet crater. This crater was found near a lava flow in an area in the northern hemisphere called Chryse Planatia. Looking for "wet craters" can give clues to scientists about a surface's current or past geological make-up. Inferring from this event would lead one to believe that obviously during the time that this meteorite fell the surface of the planet was geologically active, and the atmosphere was not thick enough to burn it up on entry. So how old is this crater? That is what Mars experts want to know.

Dry Craters

The southern hemisphere of Mars is much like our moon. The southern hemisphere of Mars has no volcanic activity, neither does the moon. You are probably saying what does that have to do with craters? Well, lots actually. Every time a volcano erupts it distributes its lava and rocks all over the nearby surface. Literally renewing the surface and giving it a makeover. If no eruptions occur in a certain area and many meteorites fall to the surface then the surface would remain heavily cratered.