When I used to drive back and forth to the college where I taught, (55 miles each way, every day, 110 miles a day for 20 years), I drove in rain sleet, snow and fog.  The fog was the worst.  You couldn't see at all.  I would get behind a semi and drive by his tail lights praying that the person driving the semi could see the road.  It gave new meaning to the phrase, "I'm in a fog."  It was so dense on those October mornings that I literally could stretch out my arm and not be able to see my fingers.

That's part of what I think God was separating when he separated 'the waters from the waters.'  The world was in a fog.  Some animals that were left behind--and lived through the great destruction (between vs. 1 and vs. 2) probably couldn't see very far, but had a keen sense of smell to seek prey.  They were meat eaters.  Plants, for the most part, had vanished for lack of sunlight causing a huge disruption in the food chain. Plant eating animals began to die out.  Perhaps those animals that ate the plant eaters began to eat each other.  Domino effect.  Extinction happened rapidly.

Vegetation had to be able to live without the sun.  Some plants lived. Certain types lived under water.  In the fossil record there are a lot of ferns.  Plants that lived in murky conditions.

So.  Land appears.  The sun is out.  The fog is gone.  The atmosphere is cleared of ash and perhaps  debris.  (Think of the Oklahoma dust bowl as thick as dense fog.)

Genesis 1:9-10  "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.  And God called the dry land Earth; and the gathering together of the waters called he Seas:  And God saw that it was good.

God is preparing something.  Something different is happening.  Very different than what was before.