SEDIMENTARY AND METAMORPHIC ROCKS T5 
The majority of the sedimentary rocks, however, have 
been formed in the ocean, and it is these which are of 
chief importance in geology. 
Soil Rock. The fragmental rocks are named accord- 
ing to their texture. The soil, which is usually the 
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Fic. 26. 
A pebble made of two layers, pebbles above and sand below. 
result of the disintegration of the rocks, is one of the 
most common. It varies in texture from clay to 
gravel, and is really a gradation between the solid 
rock and the fragmental deposits which are made by 
its removal (see p. 120). 
Pebbly Rocks. At the base of a cliff there is an 
