Why does Mars appear to have more rocks than Earth?
The Earth is covered 70% by ocean water, and the land surfaces have a fair amount of plants and tree cover. Mars has neither oceans or vegetation, although it does have polar caps. The Viking 2 landing site 20% rocks The Viking 1 landing site 6% rocks For the three landing sites we have explored (Viking 1, Viking 2, and Pathfinder), the area fraction of the surface covered by rocks ranges from 5 to 20%. For all of Mars, averaged over a few tens of kilometers, a rough estimate of the range in rock abundance is 1 to 30%, with an average of about 5%. The Viking 2 site is rockier than 95% of the surface of Mars. The rock abundance of the Viking 1 site is more typical of Mars. There is a lot of land on the earth that is just as rocky as the rockiest places on Mars, but there is also a lot of land on Earth that has fewer rocks, due to the breakdown of rocks into organic soil. To learn more about Earth soils click here. 2) Was Olympus Mons ever smaller? Yes. All volcanoes start out small and
