In the Red Beds of Texas 259 



is, turned to stone, and one often hears the expres- 

 sion petrified wood as meaning wood which has 

 turned to stone; as if there were a process in nature 

 by which one substance could be turned into another, 

 as the philosopher's stone would have changed iron 

 to gold. As a matter of fact, the process denoted 

 by the word petrifkation is a process of replacement, 

 not of transmutation. After the death of these 

 ancient animals and the decay of their flesh, the 

 water that passed through the bones carried from 

 the cells of which they were made up the organic 

 contents which decay, and left in their place deposits 

 of the silica or lime which it held in solution. The 

 same process continued when the lagoon bed was 

 elevated above the water as solid rock. The rain- 

 water, seeping down through rock and fossil alike, 

 left in the bone cells the mineral matter it was carry- 

 ing, until they were filled with it. Then, in process 

 of time, the cell walls are broken down and rebuilt 

 with silica or lime, and complete fossilization, or 

 petrifaction as it is called, takes place, as in the case 

 of the fossil bones in the Texas Permian. I found 

 one specimen of the ladder-spined reptile in which 

 the bones had been entirely replaced by iron ore, and 

 others made up of silica. 



How long does it take for the mineral matter to 

 replace entirely the original bones? Ages upon 

 ages. I found on the plains of Kansas a quarry of 





