Geology of the Rocky Mountains Japan, Indonesia and the Aleutians; others are fragments of oceanic crust obducted onto the continental margin while others represent small isolated mid-oceanic islands. Magma generated above the subducting slab rose into the North American continental crust about inland. Great arc-shaped volcanic mountain ranges, known as the Sierran Arc, grew as lava and ash spewed out of dozens of individual volcanoes. Beneath the surface, great masses of molten rock were injected and hardened in place. For 270 million years, the effects of plate collisions were focused very near the edge of the North American plate boundary, far to the west of
Journey to the Center of the Earth (attraction) to the facility's base station one half mile below. In this base station is a huge steam-powered bellows that pumps fresh air down from the surface, massive spring-pillars that hold the ceiling up to prevent cave-ins in case of earthquakes, and communication center which is currently giving warnings of increased seismic activity, but the scientist who mans it is currently away on a tea break. Riders then board steam-powered mine vehicles that travel through pre-drilled tunnels into the heart of the Earth. The ride begins through a cavern of colorful glowing crystals, before entering a giant Mushroom Forest, which is