BULLETIN 



OF THE 



SomHern Gaiilornia flGadoiiiy ol Sciences 



VOL. I LOS ANGELES, CAL, DCCmBCR I, 1902. MO. 10 



231 "West First Strket. 



NiCAt 



PREHISTORIC CALIFORNIA/^^ 



( Continued from November Bulletin ) 



BY DR. LORENZO GORDIN YATES. 



These fossils m many instances owe their preservation to the 

 originals having been submerged in alkahne waters holding silica 

 in solution, and heated by volcanic action. Sometimes forests oi 

 trees have been submerged and still remain standing in the soil 

 in which they grew, furnishing unmistakable and indestructible 

 evidence of cataclysms resulting irom seismic disturbances, of 

 which perhaps no other intelligible records remain. 



In other instances the forests were uprooted or broken down 

 by avalanches of volcanic mud, or rushing water and buried by 

 volcanic material deposited by the water, or by showers of vol' 

 canic ash. 



One of the most noted "petrified forests" of California is 

 located in Napa County, about ten miles south of the summit of 

 Mount St. Helena, an extinct volcano which is supposed to have 

 caused the death of the trees then living and their subsequent 

 preservation in the fossil state. The late Professor O. C. Marsh 

 described his visit to the locality with a party from Yale College 

 in 1870.* He says : 



"A careful examination of the locality where the first pros- 

 trate trunks had been discovered soon made it evident that those 

 now on the surface had all been weathered out of the volcanic 

 tufa and sandstones, which form the summit of this part of the 

 mountain ridge. Several large silicified trees were, indeed, sub- 

 sequently found in the vicinity, projecting from the side of a steep 

 bluff, which had partly escaped denudation. Extending our ex- 

 plorations among the mountains for several miles around, we 

 were rewarded by the discovery of many additional fossil trunks 

 at various points, showing conclusively that this Tertiary deposit 

 contained the remains of an extensive forest of very large trees, 

 which had apparently been overthrown and entombed JDy some 

 volcanic irruption. Portions of nearly one hundred distinct trees 

 scattered over a tract three or four miles in extent, were found 



^American Journal of Science and Arts, Vol. I, Ap. 1871. 



