358 



5. F. ADAMS 



<^^a. 



The hand specimen measures four by three by two inches 

 (Fig. i). Worn and rounded corners indicate that it is float, 

 for which reason the horizon from which it came cannot be 



more definitely estab- 

 ■" * " Hshed. The specimen is of 



two distinct colors, a buff 

 outer part which may cor- 

 respond to sapwood, and a 

 dark-gray inner part which 

 may have been heartwood. 

 The former is dolomite, 

 the latter silica. QuaHta- 

 tive analysis of the dolo- 

 mite gave roughly half as 

 much magnesium as cal- 

 cium and an appreciable, 

 though not large, amount 

 of iron. The general buff 

 color throughout the dolo- 

 mite is due as much to the 

 oxidation of this iron as to 

 organic matter. Both Pro- 

 fessor D. H. Campbell and 

 Professor Leroy Abrams, of 

 Stanford University, have 

 determined the wood as 

 that of gymnosperm and 

 almost assuredly coniferous. Due to the imperfect preservation 

 of fiber, further identification was not made. 



In the center of the specimen is a spot of darker brown color 

 containing rather coarse dolomite crystals. In this place a feature 

 which has been described by E. T. Wherry^ (in an account of a 

 petrifaction by calcite from Yellowstone National Park) is rather 

 prominent, e.g., the individual or compound convex-bordered 

 crystals in a siliceous matrix. On either side of the central darker 

 area is the buff mass of dolomite replacing the outer portion of the 



^ E. T. Wherry, Proc. U.S. Nat. Museum, Vol. LIII, pp. 227-30. 



Fig. I.— Wood replaced by dolomite. Gray 

 part is compact dolomite showing radial lines 

 and small black siliceous dots, which may rep- 

 resent location of resin ducts. In center of 

 specimen is coarser dolomite in rhombs and 

 compound groups. Black portion, showing 

 annual rings, is quartz. (Shghtly reduced.) 



