VARIOUS KINDS OF FOSSIL PLANTS 7 



nizable as plant or animal remains they are commonly 

 called " fossils ", and it is from their testimony that we 

 must learn all we can know about the life of the past. 



If we would find such stones for ourselves, the 

 quarries offer the best hunting ground, for there several 

 layers of rock are exposed, and we can reach fresh sur- 

 faces which have not been decayed by rain and storm. 



l r ig- i. The Face of a Quarry, showing layers or "beds" of different rock, a, b t and c. 

 The top gravel and soil s has been disintegrated by the growing plants and atmosphere. 



Fig. i shows a diagram of a quarry, and illustrates the 

 almost universal fact that the beds of rock when undis- 

 turbed lie parallel to each other. Rock a in the figure 

 is fine-grained limestone, b black friable shale mixed 

 with sand, and c purer shale. In such a series of rocks 

 the best fossils will be found in the limestone; its harder 

 and finer structure acting as a better preservative of 

 organisms than the others. In limestone one finds both 

 plant and animal fossils, very often mixed together as 

 the flotsam on the shore is mixed. Many limestones 

 split along parallel planes, and may break into quite 



