I personally adhere to the "gap theory" when I look at the first chapter of Genesis.  It is the only reasonable Biblical theory that incorporates geological, anthropological, and archeological truths  such as: there were dinosaurs.  They existed.  They vanished.  And then there was a "strata gap" before other animals appeared.  Other theories are a stretch, and don't fit observation.

Science wants to connect the layers of strata--but so far, they haven't been able to even come close.  The "Evolution Theory" requires intermediate forms  located in strata.  But there aren't any.  The missing links are in the millions and millions and billions.   The only life forms that seemed to survive were those that lived in water.  And those life forms look today like they did millions of years ago.  They didn't evolve into something else. There are those who say that the earth is not that old and that the dinosaurs were killed by the flood.  But no where in the account in Genesis (concerning the creation of animals) does it refer to God creating the types of dinosauric animals that went extinct.

I could go on and on about all that.  Suffice to say, I have spent years on this subject and explored dozens of theories, and more than proved the truth of Genesis to myself as a scientist.

Here is what I believe.  God didn't tell us very much.  Maybe because it isn't relevant to the here and now.  I don't know.  But I believe in words, and the words say: Genesis 1:1 "In the beginning, God created the heaven and the earth."  Period.  He doesn't tell us what all that involved, or what all he put in this earth and heaven that he created.  What it does tell us is that he "Created" it.  He made it out of nothing.  He made it perfect.  He made it exactly like he wanted it.

And then something happened.  He doesn't tell us what it was.  But what the words do tell us is that somewhere between verse one and two, something happened.  Because in verse two we do not see a "Creative" work.  We see a mess.  Dark.  Void. Without form.  That is not a creative work.

We get puffed up about being in the human race--since Adam and Eve--and don't consider that there may have been an entire world designed before that.  I don't know.  What I do know is that there is strata and there is carbon dating, and there are really old bones.  All kinds of bones.