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.
The ages measured for Earth's oldest rocks and oldest crystals show that the Earth is at least 4.3 billion years in age but do not reveal the exact age of Earth's formation. The best age for the Earth (4.54 Ga) is based on old, presumed single-stage leads coupled with the Pb ratios in troilite from iron meteorites, specifically the Canyon Diablo meteorite.