The top routes that United Airlines flies are: 1  CLT to ORD with 3,755 flights per month. 2  CLT to IAH with 3,511 flights every month. 3  DFW to ORD with 3,486 flights every month.  DFW to EWR with 3,268 flights every 1  month. PHL to ORD with 3,238 flights every month.
The first of the three rock types to form on Earth were the igneous rocks; formed from the cooling and solidification of magma, as the Earth was at one time completely molten. â¦. 4 people found this useful.
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.