New insights on the geology, stratigraphy, paleontology, and archeology of Petrified Forest National Park were presented by park superintendent Brad Traver last week at the Little Colorado River RC&D Winter Watershed Conference in Show Low. His slides from that talk are now available online.The title of his talk was "The Petrified Forest you don't know."
I think you'll come away too with a much greater appreciation of the incredible resources there.
In learning about petrified trees, there's one thing that was pointed out to me that doesn't make sense. From what it seems, the process starts with a tree dying. That tree trunk stands there while sediments accumulate around it, eventually covering it up so it petrifies. Well, the part that doesn't make sense is how long it takes for all those sediments to cover the tree. Since the tree is pretty intact, it wasn't there long enough to break down much. So, does that mean all those sediments, which are supposed to take thousands of years to accumulate really have accumulated in the brief time that it takes for a tree to erode from the elements?
ReplyDeleteIt is unusual for trees to be fossilized standing up. When that does occur, it's often because they have been rapidly buried, by ash fall from a volcanic eruption, a mud flow (if it doesn't knock it over), sudden change in river or channel courses, sand bar depositions, etc.
ReplyDeleteMost trees that are fossilized have fallen over. And yes, those on high ground or in areas of slow sediment accumulation are like to decay before they would be preserved.
So, the small portion of trees that are preserved are those that fall into low areas where rapid sedimentation buries them and slows or halts oxidation. Note that the ancient PFNP environment includes meandering streams with a variety of local areas where downed trees can be trapped.