TABLE OF STRATIFIED ROCKS 



SHOWING APPROXIMATE THICKNESS. 



SILURIAN ^_- 



. ;^ooo ft —_——- 



WJWUWiJil: 



Fig. 41. — A tabular 

 view of the strata 

 of the earth's 

 crust, showing the 

 relative thickness 

 of each " system " 

 or grovip of strata, 

 and the position 

 in which impor- 

 tant animal re- 



I'i'ilMl-: 



I I ' I ; OROOVIC 



' i'/'ifi/'/.'i';r/-/.m-\ 



FIRST TRILOBITES 



mains have beei) 

 discovered. Th( 

 rocks are neve" 

 found lying hori- 

 zontally like this, 

 which is a diagram 

 In nature they art 

 tilted and crum 

 ])led, but we cai 

 make out theii, 

 thickness and th<| 

 order in which the^ , 

 lie one over thi 

 other. 



