Since I’m pontificating here, let me add something else. Trying to explain all these points to someone largely ignorant of basic science is well nigh impossible, and takes considerable patience and careful planning. For example, before anyone can really grasp evolution they must first understand that astronomy, cosmology, physics and geology all agree that the Earth is 4.6 billion years old, and that the Sun is about 5 billion years old, and the universe as a whole is about 13 billion years old. And to understand those conclusions, they have to understand the atomic theory, the concept of radioactive decay, the electromagnetic spectrum, the cosmological redshift, tectonics, erosion, stratigraphy, fusion and fission, to name but a few.

The Map That Changed the World: William Smith and the Birth of Modern Geology would be a good starting point for someone sitting on the fence between creationism and reality. It really explains how geology and biology informed each other during the 18th century, and how stratigraphy provided people like Wallace and Darwin the foundations for evolutionary theory.