In the early days of geology, especially during the 17^th and 18^th centuries, the dominant explanation for the sedimentary rocks and their fossilized contents was that they had been laid down in the great Flood of the days of Noah.

There is the theory that all living things have arisen through a naturalistic, mechanistic evolutionary process from a single source, which itself arose by a similar process from a dead, inorganic world. This general evolutionary hypothesis is usually presented as an established scientific fact in science textbooks.

The study of biological processes and phenomena indicates that significant evolutionary developments are not observable in the modern world. Similarly the great gaps in the fossil record make it extremely doubtful that any genuine evolution, as distinct from small changes within the kinds, ever took place in the past.