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.
1Zircon Crystal (4.4 Billion Years Old) This ancient zircon crystal is the oldest known material formed on Earth. Scientists have dated the crystal to about 4.4 billion years, making it the earliest confirmed piece of the planet's crust. The crystal was found in an arid region north of Perth, Australia, in a low range of hills called the Jack Hills, in 2001.