v.] THE LIME IN THE MORTAR. 125 



land. For coal, or fossilised vegetable matter, be- 

 comes more and more common as we ascend in the 

 series of beds ; till at last, in the upper coal-measures, 

 the enormous wealth of vegetation which grew, much 

 of it, where it is now found, prove the existence of 

 some such sheets of fertile and forest- clad lowland as 

 I described in my last paper. 



Thousands of feet of rich coral reef ; thousands of 

 feet of barren sands; then thousands of feet of rich 

 alluvial forest and all these sliding into each other, if 

 not in one place, then in another, without violent 

 break or change ; this is the story which the lime in 

 the mortar and the coal on the fire, between the two, 

 reveal. 



