FIELD GEOLOGY. 203 



the local strike, or rather outcrop, of the beds of which 

 it is composed. In a country abounding in continuous 

 escarpments, long ridges, and sweeping valleys we might 

 naturally expect to find a tolerable consistency in the 

 inclination of the strata; in a rugged broken surface 

 we should see indications of sudden changes of dip, 

 both in amount and direction, of faults, fractures, and 

 contortions. 



The next step would be to visit all the quarries, lime- 

 kilns, brick-yards, or coal-mines, the existence of which 

 we have been able to ascertain, and in all of them, 

 by inspection and inquiry, obtain some useful infor- 

 mation. By this means we get a good general idea of 

 what the rocks of the district are, of the formation to 

 which they belong, of their local nature and charac- 

 teristics. 



Assume all this to have been done, and that we 

 are about to map in detail an area, the rocks of which 

 consist of a Red Sandstone and a series of Limestones 

 (? Permian) overlying the " Upper Coal-measures." We 

 have visited the three quarries in the Sand and Lime- 

 stones shown on the map, fig. 21, ascertained that in 

 two instances the dip is due S. 10 and 14 respectively, 

 due N. 5 in the third. This evidently indicates an 

 anticline (or possibly a series of faults) which has 

 brought up the underlying Carboniferous rocks nearer 

 to the surface, and given origin to the valley by which 

 they have been exposed (p. 36). To avoid confusion, the 

 roads, &c., are omitted from the map, and the quarries 

 numbered in the absence of other means of identifi- 

 cation. 



