62 GENERAL DISTRIBUTION OF THE 



of great interest, which will form especial objects of 

 discussion hereafter. 



Although the forms of land are connected with and 

 dependent on the dispositions of strata, as well as 

 on those of the unstratified rocks, there is no rule, in 

 this respect, universally applicable. A few examples 

 will serve to convey that general notion of this sub- 

 ject which is all that is required for the present pur- 

 pose. If a series of strata be perfectly horizontal, it 

 is easy to understand that the land above it will have 

 a corresponding level. If it be slightly elevated, it 

 must, unless it be curved, unavoidably terminate 

 somewhere, by fracture or discontinuity; and the 

 surface will thus form a low ridge, of which the decli- 

 vity which lies on the plane of the stratum, will be 

 more gentle than that which belongs to the abrupt 

 edges. The continuity of that ridge being inter- 

 rupted by other transverse fractures, and other ridges 

 occurring in a disordered manner, there is thus pro- 

 duced a land of low hills, which may also be equally 

 generated by analogous irregularities in the forms and 

 dispositions of unstratified rocks. 



If such an elevation of a series of strata be increased, 

 there is produced a mountain ridge, which may also 

 be broken into detached points, so as to form irregular 

 but continued chains. Here the planes of the strata will 

 form declivities more or less smooth ; while the 

 abrupt edges will become the precipices so common in 

 mountainous regions. Undulations of such strata, 

 which have been here supposed straight, will generate 

 corresponding irregularities ; and thus, in low countries 

 in particular, ,the inequalities are often produced, as 

 much by undulation, as by unequal elevation and frac- 

 ture ; while thev are also occasionally the result of 



