Poetic Genesis
Some say Genesis is just poetry, and you can't take poetry literally. However, poetry can describe something that is literally true, in a figurative way. There is "plain literal" and "figurative literal".
Plain literal is simply stating something in a straightforward direct way. Figurative literal is describing something in a creative way and as Genesis is referring to creation, it's not surprising that this method is used. A study of the Hebrew grammar within the first 11 chapters of Genesis indicates the same literary style as the rest of the book.
As Professor Barr stated (see Six Literal Days ), scholars of Hebrew believe that if you take the Bible in isolation (and you don't try to "factor in" what you think science indicates) then there were six literal days and the Bible clearly teaches that the Universe is young.
Some say that the Hebrew word for day ("yom") doesn't always mean 24 hours - it can mean a long period of time. This is true, but not when it is used with a number (i.e. "the first day"), then it always means a literal day.
If Genesis is symbolic, where do you draw the line?
Genesis 1 uses the words "morning" and "evening", referring to a day.
Often 2 Peter 3:8 is quoted to suggest long periods of time: "With the Lord a day is like a thousand years, and a thousand years are like a day." but this was written in Greek, not Hebrew, and is a different context.
There is also internal consistency within the Bible: the six days are referenced in Exodus 20:11 "For in six days the Lord made the heavens, the earth, the sea, and everything in them; then he rested on the seventh day." Not only does this refer to the six literal days of creation, but it establishes the 7 day week, including a day of rest on the Sabbath.
Many refer to a contradiction between chapters 1 and 2 of Genesis. However, it is just a case of understanding the structure and time line of the book. Genesis Chapter 1 verse 1 up to Chapter 2 verse 4a is a summary of creation. The rest of Chapter 2 then goes into more detail about the creation of mankind, the pinnacle of creation.
Here are some excerpts from Genesis 2,
"When the LORD God made the earth and the heavens- and no shrub of the field had yet appeared on the earth" i.e. the earth and heavens (sky and space) occurred before vegetation, consistent with Genesis 1.
"Streams came up from the earth and watered the whole surface of the ground - the LORD God formed the man" i.e. water appeared before man.
"Now the LORD God had planted a garden in the east, in Eden; and there he put the man he had formed." i.e. the garden was there before man, notice the past tense, the garden must have been created first, before God could put man there.
"Now the LORD God had formed out of the ground all the beasts of the field and all the birds of the air." i.e. the animals were created before man, again notice the past tense. There is no contradiction in the sequence of creation if the language is studied carefully.