Exploratour - The Surface of Mars
Tharsis Ridge
This picture shows the Tharsis Ridge, the green area in the middle of the picture. The green areas are higher than the blue, and the yellow and orange parts are the highest of all. The red line in the picture is the spacecraft measurement which indicates just how large the regions are compared to one another.
The Tharsis Ridge is a region about twice the size of the United States (8000 km), and is where many of the volcanoes of Mars are found. This region of Mars is actually a giant bulge, as shown in the picture.