268 ELEMENTARY GEOLOGY 
the reverse is true, for on the land there are scarcely 
any strata that were laid down in the deep sea. 
Excepting in a few localities, the sedimentary strata 
are either limestones or fragmental rocks made of 
particles of waste from the land. 
Evidence of Shallow Water Origin. Among these 
fragmental rocks we often find distinct evidences of 
formation in shallow water, and in some cases that 
Fic, 152. 
Cross-bedding in a gravel bank. 
* 
they were deposited at the very shoreline. Sometimes 
the strata have been laid down at various angles, 
giving the appearance of great disturbance. This is 
known as cross or current-bedding (Fig. 152), and is 
due to rapid variations in the direction and force 
of the currents that were bringing the sediment. 
When present, cross-bedding is usually found in sand 
or gravel beds, and at any time we may see it forming 
