2.9" Stromatolite Covered Petrified Wood Limb - California

This is a limb section of Miocene aged petrified wood algal casts from San Bernadino County, California. One face of this limb section has been polished to show of the inner wood detail. This is an example of a fresh water "tree hugging" stromatolite. In cyclical environments, as the climate shifts from arid to humid, the trucks and roots of flooded trees serve as temporary habitable zone for the anciently evolved stromatolites.

Autoradiography of the Barstow stromatolites suggests that the bacteria that form the coating were also involved in uranium mineralization. As the climate becomes more humid, previous desiccated flats are vegetated. As the expanding lake floods these stromatolites encrust the trunks and exposed roots of the drowned vegetation.

Petrified wood is the name given to wood that has been turned into stone (fossilized) through the process of per mineralization. All of the organic matter becomes replaced by minerals, while much of the original structure such as tree rings in retained. For this to happen the wood needs to be buried in an environment both low in oxygen (preventing decomposition) and with flowing mineral laden water.