The Soil 



action have thrust rocks from below through the mass 

 above, forming traps or dikes, the nature of the rock 

 itself demonstrates its origin. 



If we dig a well we come first to what we 



Formations ^^^^ ^^^^' ^^^^ ^^ darkened in color by the 

 decay of vegetation. Then we find a bed of 

 clay, and below this sand. It is evident that the sand 

 was there first, owing to its superior weight, and that 

 the clay and soil were afterward deposited on top of it. 

 Then, if we find another bed of clay imder which is a 

 bed of sand, we can easily determine that there were 

 successive deposits elevating the land. In a similar way 

 geologists have studied the growth of the layers or strata 

 that make up the thousands of feet accumulated on the 

 surface of the original earth crust. If the geologist bores 

 into a bed of sandstone and below that finds a bed of 

 coal, formed from the decay of vegetation, it is evident 

 that this vegetation must have grown on the original 

 surface, and that the sandstone was of later formation. 

 When under the coal he finds a bed of clay loam with 

 the roots of the old forest penetrating, he is strengthened 

 in his beHef as to the formation of the coal. 



Again he finds a bed of hmestone filled with the fossil 

 remains of shellfish and coral — the plainest evidence that 

 living creatures formed these shells and coral before the 

 soil was formed and before trees grew from which the soil 

 was formed, and that the limestone formed from their 

 remains must be older than the coal formation above 

 them. When under this limestone there is found a differ- 

 ent rock that further on projects into the surface of the 

 hills, he would argue that this rock, being under the 



