CHAPTER VII 

 THE FIRE-HARDENED ROCKS 



SO far we have been considering the deposits laid 

 down, for the most part, in a leisurely and orderly 

 manner, by the action of air and water ; by floods, 

 rivers, lakes, the sea, or by the slow movements of ice. 

 If these, however, had been the only agents by which the 

 earth's strata were accumulated, then it is clear that for 

 the most part these deposits and these strata would lie 

 evenly, one on top of the other, like the lines of print on 

 this page. But as a matter of observation the earth's 

 strata do not lie like that. If we were to tear this page 

 out and crumple it up in a ball, first having torn it in 

 half and shredded a few irregular pieces out of it, we 

 should get a truer picture of the way in which many of 

 the earth's strata are contorted, crumpled, and displaced. 

 They have not been so distorted by the action of the sea, 

 violent as are some of the sea's assaults on the land ; nor 

 would the heat of the sun at its greatest ever produce 

 such effects. They must have taken place from some 

 causes which arise in the earth itself. These causes can 

 be summed up in one word fire. Some of the strata 

 of which we have spoken, and which are called sedi- 



