Sediments

Question: Can someone explain how fossils get trapped in sediment that takes (in some cases) thousands of years to accumulate? What is wrong with testing a hypothesis that only cataclysms (volcanic eruptions, earthquakes, meteor strikes, etc.) produce the conditions necessary for trapping an organism and preserving its structure, before decay or absorption or scavenging of the organism can occur?

Thanks. That explanation does help. Any thoughts on whether or not the Grand Canyon in Arizona was formed by massive (multiple) volcanic explosions, a la Mt. St. Helens?This is a critical question for Creationists, because young earth theories require the layers formed in the Canyon to have been deposited rather quickly. Similarly, it is critical for Evolutionists, because the layers formed in the Canyon (and correlated in other locations around the world) are relied upon to establish an approximate age for the earth of several billion years.

Excellent answers. I'll visit this site more often when I have more questions.Would a question about geological phenomena (such as material absorption and leaking, or leaching) belong under sediments? Or should it be treated somewhere else?