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.
MINERALS. CRYSTALS. GEMSTONES. FIND OUT MORE. Earthâs crust is made of rock, and rock is made of natural substances called MINERALS. There are three main types of rockâsedimentary, igneous, and metamorphic rock. Each type is produced in different ways.The oldest rocks on Earth were formed about 3.8 billion years ago.INERALS. CRYSTALS. GEMSTONES. FIND OUT MORE. Earthâs crust is made of rock, and rock is made of natural substances called MINERALS. There are three main types of rockâsedimentary, igneous, and metamorphic rock. Each type is produced in different ways.