Outside The Interzone: OMN Willamette Valley Geology Presentation Part Four: WV Rocks! | Conformable Contacts | Scoop.it

Interesting tour of geologic features of the Willamette Valley, Oregon.  The above photo is of "permineralized charcoal," which sounds very odd.  The blogger writes about the variety of petrified wood in the area:


"The fossilized wood in the Sweet Home- Holley area is spectacularly preserved, with even the finest details observable in thin sections under a microscope. A particular puzzle with respect to this "petrified forest" is its diversity. Over 60 taxa have been ID'd, ranging in environmental affinities from subtropical to boreal. The Cascades were, at the time, low relief, so we can't call on elevation changes as we might today. Ideas include transport from the hinterland, and driftwood coming in from the North."


As with the Petrified Forest in Arizona (http://tinyurl.com/cmxkrg4), permineralization by siliceous waters is the usual mechanism ascribed to the formation of petrified wood.  First, the wood has to be buried deeply and quickly enough to be preserved from decay, and next, it needs to be exposed to the mineralizing waters.  Sounds more consistent with a catastrophic process than a gradual one.