The Earth is a ball of rock 7,927 miles in diameter. The inner core is very dense, heavy and tremendously hot. The heat melts the mantel rock, as the molten rock rises it cools and hardens and then sinks to be remelted again and again. This constant process of heating and cooling rock creates movement in the Earth crust. The rock becomes lighter and less dense as it nears the surface.
The Rock and Mineral Challenge
| See how ocean ridges form | See how valleys form | See how mountains form | See how volcanos form | See surface forms |
Produced with the assistance of the Illinois Department of Natural Resources and the Illinois State Museum.
The
Lizzadro Museum of Lapidary Art