CompuServe Messages

Hi, Rande– While it must be common for fossils to be washed away from their home stratum, it will be less common for them to get built into a new rock – the odds are they will be destroyed by weathering first. If one can see how they fit into the parent rock, one will often be able to tell there is a risk of anachronisms. These washed-down fossils of yours, if incorporated in a new rock, would likely be in a conglomerate where one has to suspect such things of fossils found _within_ the conglomerated units. Even if it winds up in a uniform smoothly-bedded rock, the particular rock the fossil arrived in will be an oddball, a section with different angling of layers and different kinds of sediment. I was assuming above that the fossil is still embedded in a piece of its home rock; if not, it is more vulnerable to the weathering I spoke of. The other fossils at the site taken together may tell a consistent story or a discordant one (as they would at your arroyo), which would have a bearing on interpreting any one fossil. Your arroyo seems likely to appear as some sort of projection at the boundary of whatever layer it winds up in. I suspect paleontologists are more comfortable with specimens from the body of a formation than some extension. Without knowing the exact point in the formation the fossil was found in, suddenly there would be a lot less to go on, and the fossil would lose a lot of its value as a source of information. There may still be radioactive dating or some such, but that will often not be possible. –Doug