Posted 28 April 2012 - 05:36 PM
"Fossilization is a process that can take anything from a few hours to millions of years ... The amount of time that it takes for a bone to become completely permineralized is highly variable. If the groundwater is heavily laden with minerals in solution, the process can happen rapidly. Modern bones that fall into mineral springs can become permineralized within a matter of weeks."[1]
They know fossilzation can happen within "a few hours" to "a matter of weeks", because they've seen this happen. They've never seen fossils forming over "millions of years", so it is an assumption that is not based on observation.
During the global flood, the groundwater would have been "heavily laden with minerals in solution".
"A great deal has changed, however, and contemporary geologists and paleontologists now generally accept catastrophe as a 'way of life' although they may avoid the word catastrophe. In fact, many geologists now see rare, short-lived events as being the principal contributers to geologic sequences ... The periods of relative quiet contribute only a small part of the record."[2]
[1] Philip J. Currie & Eva B. Koppelhus, 101 Questions about Dinosaurs, (Dover Publications, 1996), p.11.
[2] Raup, David M., "Geology and Creationism," Bulletin, Field Museum of Natural History, vol. 54, p. 21, (March 1983).