Ch. XIII.] THE INCLINED POSITIONS OF STRATA. 273 



forests which invariably occur on our coasts, at or immediately 

 beneath low-water mark, be attributable or not to the ele- 

 vation or depression of the land by volcanic influence, one 

 thing is certain, that there has been a repeated alteration in 

 the relative level of sea and land, and that these changes 

 have been accomplished without affecting the inclination of 

 the strata. 



Having considered some of the leading phenomena of the 

 central fire, as indicated in volcanic districts, we now proceed 

 to enquire whether the igneous rocks found in the fossiliferous 

 strata exhibit the same appearances. 



Basalt and other trap-rocks do not appear to have acted 

 on the adjoining strata in a different manner. They are 

 found overlying the strata of each geological epoch, in masses 

 which are more or less regularly disposed ; they intersect the 

 strata in different directions, in the form of dykes, which are 

 connected with masses of a similar nature, either at the 

 surface or beneath, or descend to unknown depths ; but, in 

 all these cases, the sedimentary rocks are frequently found 

 in their original position, exhibiting no marks of angular 

 disturbance. 



Thus, in Sicily, a country which is at present, and which 

 appears to have been during the tertiary epoch, peculiarly 

 liable to volcanic convulsions, the stratified rocks of this 

 period do not present those inclinations and contortions which 

 we are taught to attribute to igneous catastrophes. " The 

 disturbance," says Lyell *, " which the newer pliocene strata 

 have undergone in Sicily, subsequent to their deposition, 

 differs greatly in different places ; in general, however, the 

 beds are nearly horizontal, and are not often highly inclined. 

 The calcareous schists, on which part of the town of Lentini 

 is built, is much fractured, and dip at an angle of 25 to the 

 north-west. In some of the valleys in the neighbourhood, 

 an anticlinal dip is seen, the beds on one side being inclined 



* Principles of Geology, vol. iii. p. 73. 

 T 



