106 



of disturbances to which that particular part of the earth's sur- 

 face has been subjected. Extensive ranges of country often 

 have the beds of rock of which they are composed thrown into 

 particular lines of direction. Such lines, when considered in the 

 usual manner with reference to our general ideas of distance, 

 appear of considerable length ; but when viewed, as they should 

 be, in connexion with the whole superficies of our spheroid, a 

 large proportion of them lose their apparent importance : many 

 of them are then seen to be so short, that the cracks or eleva- 

 tions of strata by which they are marked may readily be con- 

 ceived to have been effected by comparatively small intensities 

 of force. It is a want of due attention to the relative propor- 

 tions of the radius of the earth to the height of mountains and 

 the undulations of strata, which is probably ~the cause of such 

 disturbances being considered as the result of forces so tremen- 

 dous as those arising from an igneous nucleus and a broken 

 shell. (See Plate XX.) Most gigantic and awful igneous forces 

 1/ are now commonly brought forward to account for disturbances 

 which could be effected by an ordinary hydrostatic press con- 

 nected with a subterranean sheet of water. 



The gradual northerly crystalline action of the Dartmoor gra- 

 nite tilting the southern edges of the strata of North Devon 

 has been ascribed to an igneous eruption. It is a singular fact 

 that the sedimentary beds are principally tilted on the southern 

 edges in Europe and America, indicating very forcibly the effects 

 of a northerly action. 



When we minutely examine the faults in coal-fields, we have 

 abundant proofs that they were not the effect of volcanic con- 

 vulsions or earthquakes, but the result of a quiet, uniform ope- 

 ration of nature. Movements, fractures and dislocations, of such 

 order, regularity and extent as we find in the whole masses of 

 rocks constituting the surface of the globe, require a correspond- 

 ing, slow, regular and powerful acting cause, such as that which 

 we find in the operations of terrestrial magnetism. Volcanoes and 

 earthquakes are merely secondary forces, i. e. the effects of the 

 subterranean currents ; therefore even the local and irregular 

 effects from these actions must be classed under the same natu- 

 ral operation as those above alluded to. It is anything but de- 

 sirable to have constant recourse to great forces in explaining 



