But the cotton gin also resulted in the expansion of slavery in the South. Because cotton is a labor-intensive crop, the spread of cultivation deepened and broadened the region's dependence on slave labor. While southern planters would reap great profits as a result of his invention, Whitney was less fortunate.
1 The oldest rocks on Earth, found in western Greenland, have been dated by four independent radiometric dating methods at 3.7-3.8 billion years. 2  Rocks 3.4-3.6 billion years in age have been found in southern Africa, western Australia, and the Great Lakes region of North America. Rocks 3.4-3.6 billion years in age have been found in southern Africa, western Australia, and the Great Lakes region of North America. 2  These oldest rocks are metamorphic rocks but they originated as lava flows and sedimentary rocks.
What are the three major types of rocks? A: The three major types of rocks are igneous, sedimentary and metamorphic. Formed deep inside the Earth, igneous rocks form when a melted rock cools and soli... Full Answer >