APPENDIX. 471 



If the general covering of soil and cultivation, in 

 low countries, forms a source of difficulty, the regu- 

 larity of the strata often produces countervailing ad- 

 vantages. Under a low position, they commonly oc- 

 cupy such large spaces, that a few points will often 

 determine an extensive tract; while, in mountainous 

 regions, the frequent changes of the rocks demand 

 much ^more labour. The first steps may indeed he 

 slow ; but when a few strata, with their successions, 

 have been ascertained, the subsequent labour becomes 

 light: while a final comparison will disclose what was 

 at first concealed. If horizontal, or nearly so, it may 

 often require time to ascertain the strata ; while quar- 

 ries, wells, and mines must be searched, for what 

 rivers seldom disclose in these cases. But such posi- 

 tions are rare, while the unequal declivities, in inclined 

 stratifications, indicate the elevated edges, which may 

 be pursued by occasional fractures and by the form of 

 the ground; as this last, with the nature of the soils, 

 aid us in tracing the succession and place of each stra- 

 tum. But if many other circumstances require atten- 

 tion, the following remarks on the description of geo- 

 logical appearances will comprise every thing needful. 

 The general character of the country, with its moun- 

 tains, vallies, lakes, rivers, coasts, and any other cir- 

 cumstances of physical geography bearing on geology, 

 first demand attention. And the alluvial deposits more 

 conveniently follow, than in the order of superposition 

 as strata, from their connection with the preceding 

 subject; permitting thus a more luminous view of the 

 whole. In these, the several kinds must be distin- 

 guished; together with their origin and causes, demon- 

 strable, or probable, and the effects they may have 

 produced as to the surface. It is by thus studying and 

 describing those of foreign and obscure origin, with 



