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
Downward to the Earth Downward to the Earth Downward to the Earth is a 1970 science fiction novel by American writer Robert Silverberg. It is a tale of the quest for transcendence (a frequent Silverberg theme) set on another planet, and includes references to "Heart of Darkness", Joseph Conrad's classic tale of colonialism, including the name of Kurtz. Its title references Ecclesiastes 3:21 in the Bible (""Who knows if the spirit of people rises upward and the spirit of animals goes downward to the earth?""). "Downward to the Earth" was originally published as a four-part serial publication, starting in the November 1969 edition of