The biggest two presuppositions are these: First, that Genesis is intended to communicate “eyewitness” information about the duration and method of God’s creation. Second, that information is communicated in such a way that one-to-one correspondences can be made between terms in Genesis and modern scientific concepts.
These two presuppositions control the way a person reads the text. It is no surprise that people find exactly what their presuppositions demand they find.
I want to return to the historical angle, because I think it’s vital. The history of conversation about Genesis and science can be summed up as this: Genesis is a theological masterpiece but a terrible scientific text. The theology of Genesis—that the universe is the free and good creation of an omnipotent and wise God—has had a massive impact on the development of the modern world, and particularly the rise of modern science. But every single time people have tried to use Genesis as a guide to science, it has failed. Every. Single. Time. So perhaps the lesson is that Genesis was not intended to give us that sort of information? Perhaps its depiction of creation is meant to communicate a different sort of truth than just a literal chronology of events? Perhaps its our own presuppositions which need to be adjusted?
This book has been extremely helpful for me: Amazon.com. Written by two professors at a conservative Bible college.
Sure, it can be understood in different ways. That’s the point. But lots of people in church history have thought the most “natural” reading is of a solid dome that separates the “waters above” from “waters below.” This also makes the most sense in the cultural context in which Genesis was written. More on that here: http://biologos.org/blogs/archive/the-firmament-of-genesis-1-is-solid-but-that’s-not-the-point
The firmament/expanse question has been debated here on the Forum at great length, so I’m not going to beat the dead horse any more than this. Here’s the biggest thread: