Most fossils are formed by minerals replacing the tissue of dead organisms with a hard minerals. The dead organism, gets buried and is thus protected from decay, and a process of “permineralization” takes place. Subsequent to fossil formation, the strata may be uplifted, or eroded, until found. Notice that the process requires water, consistent with a flood, and burial, consistent with a catastrophe.
Photo Credit: http://www.fossils-facts-and-finds.com/fossil_formation.html
Fossil Record percentages: http://www.icr.org/article/why-dont-we-find-more-human-fossils/