Studies in Genesis 1
And God said, “Let the waters under the heavens be gathered together into one place, and let the dry land appear.” And it was so. God called the dry land Earth, and the waters that were gathered together he called Seas. And God saw that it was good. (Genesis 1:9-10 ESV)
By now God has probably formed and shaped the rock into a spherical planet, probably spinning on its axis, probably revolving around a huge light which will be the Sun. Nothing in the first chapter of Genesis gives detail about the formation of the planet other than basic information.
On the first day God created all matter and then began shaping and forming that matter into what is now in the universe, telling us specifically what He is doing with the hunk of rock which will become Earth. He made light and separated light from darkness. On the second day He separated water from water, creating and atmosphere and cultivating the planet, making it ready for life.
Day three begins and God moves the geology on the planet. He creates deep rifts and high mountains, separating the dry places from those filled with water. Earth is an active planet, from its core to its surface, to the atmosphere surrounding it, to its place in the universe.
Verse 9 states God “gathered together” or collected, all of the liquid water into “one place” which may mean a single, huge ocean before he separated the continents. But “one place” probably means the deep areas with boundaries across which the waters cannot move.
God continues to separate one thing from another. From His first few words in Genesis to the last few words found in Revelation, God declares Himself and His work.