1:9 And God said, "Let the waters under the heaven be gathered together unto one place, and let the dry land appear.": and it was so.
God named the expanse above the waters the heaven. Naming creation upon the earth will be a function for Adam later. Here in 1:8, Heaven is the generic name for all the area above the ground.
We see a dark development later in Homer's Illiad when Althaia invokes the underworld gods by lying flat upon the earth, beating the ground (9.565ff). In the ancient's minds, if you were down upon the earth you were in the realm of hell or Domos Hades, the dwelling place of the unseen, not heaven. Quite different from the way God shows us the grandeur of His creation.
God speaks with a purpose again and that purpose is to give us a dry habitat to dwell in. God commands (Hebrew command form is here translated as Let-It Be is understood) that the waters underneath the expanse are gathered into an area so that a non-water covered place would arise. And it happened just this way.
The words Dry Land here are better translated as Dryness. So God says, Let-it be, the dryness appear.
This is the beginning of the Precambrian Supereon into the Archeazoic eon.
The largest defined unit of time is the supereon, composed of eons. Eons are divided into eras, which are in turn divided into periods, epochs and ages.
The most common large-scale time scale is millions of years (Megaannum or Ma), or also Mya for "millions of years ago." But long-term measurements still requires very large numbers. By using the galactic year this gives numbers that are easier to remember. The Galactic Year (GY) is the time it takes for the solar system to revolve once around the galactic core, or about 250 Ma.
By this measure, oceans appeared on Earth after 4 GY, life began at 5 GY, and multicellular organisms first appeared at 15 GY. Dinosaurs went extinct about 0.4 GY ago, and the true age of mammals began about 0.2 GY ago. The age of the Earth is estimated at about 20 GY or about 4.570 billion years old.© 2009 Roy Blizzard III