1. Compare the cratered regions of Mercury, the Moon, and Mars. Assuming that the craters on all three worlds originally had equally sharp rims, what can you conclude about the environmental histories...

1. Compare the cratered regions of Mercury, the Moon, and Mars. Assuming that the craters on all three worlds originally had equally sharp rims, what can you conclude about the environmental histories of these worlds?

2. What geologic features indicate that plate tectonic activity once occurred on Mars? What features created by tectonic activity on Earth are not found on Mars?