146 OUTLINES OF FIELD-GEOL< 



obsen ^ible indication of curvature in any of the 



beds, and yet, if we prolong tin planes of dip abov< 

 below the surface (Fig. 43) we see at once that these 

 must form a considerable curve, though with a radius so 

 large that the bending does not appear within the n. 

 strip of rock exposed at the surface. Such indications of 



FIG. 43. Section of inclined strata (as in Fig. 42), showing that they form part 

 of a large curve. 



endless undulations in the rocks of the earth's crust 

 meet the field-geologist at every turn. 



The larger curvatures can be best understood from a 

 previous examination of those on a small scale, so often 

 to be met with on coasts and in inland ravines. In such 

 cases we may advance (from say a in Fig. 44) across the 

 strike of beds dipping steadily towards us, and may not, 



