OFTEN EXPLAINED BY DISLOCATIONS OF THE STRATA. 



545 



desirable to search for more valid reasons to explain the difference of levels. Geology 

 furnishes us with these, in teaching us that our present lands have been irregularly raised 

 from beneath the ocean 1 . Some regions have been heaved up in the form of great pla- 

 teaux without many breaks ; but the vastly larger proportion of the crust of the globe is 

 absolutely starred through with rents (many examples have been cited in this work), by 

 which beds once continuous have been snapped asunder, and subsequently moved up 



limestone mountains, were deposited under water in the form of a delta, extending northwards from the central 

 chain, during the formation of which the blocks overlying the limestone peaks were probably at no very different 

 level from those now lying on the banks of the Inn. — That after the drift had been so deposited, powerful 

 movements took place, heaving up the outer shores and raising the pre-existing bottom of the sea, estuary, or 

 lake (as the case might be) to great heights, the blocks and loose materials being thus left at various elevations, 

 and in the detached positions in which we now find them. Here, we have no occasion to imagine dislocations, 

 for they teem in every mass of rock. The chasm in which the Inn flows, is indeed one great line of fault, 

 and such are the contortions and dismemberments of the whole chain, that throughout more than 50 miles from 

 east to west, the younger formations are thrown over and appear to dip under the older ! But even with such 

 evidences of mutation, I confess that in the year 1828, although I then believed that the phenomenon I am 

 describing, could be explained only by movements of unequal elevation and depression, I was not prepared 

 to go the length I now do in the solution of this problem, my 'present views being founded on the knowledge, 

 since acquired in England, of the intermixture of sea shells of unquestionable modern species with erratic blocks. 

 Now, although the rationale of icefloes, as above propounded, has rendered our appeal to catastrophes un- 

 called for in many cases, we cannot witness the scenes of dislocation in the Alps, and perceive that they are 

 accompanied by the lodgement of bowlders derived from the same source at heights so different, without also 

 employing such evidences of mutation to help us in part to solve these problems. Tf some of the greatest 

 relative changes between the sea and land have taken place in our island within the modern period, the same 

 may have also happened at a comparatively recent period in the Alps*. 



] I could have strongly illustrated these views by an appeal to evidences of recent elevations of the shores of 

 South America, but as this inquiry would lead me beyond the limits I have prescribed to myself, I must refer 

 my readers to Lyell's Principles of Geology, or for details to the works of Mrs. Graham (now Lady Calcott), 

 Mr. Caldcleugh, Dr. Meyen, and above all to the clear and unanswerable record of that distinguished navigator 

 and precise observer, Captain Fitz Roy, R.N. In describing the effects of the last earthquake at Concepcion 

 (Geographical Journal, vol. vi. p. 327.), Captain Fitz Roy has distinctly proved, that the island of Santa Maria 

 was elevated from 9 to 10 feet, while the rest of the coast on the mainland was only raised from 2 to 4 feet ; and 

 thus we see that not only in the same epoch, but absolutely during the same minute, recent sea-shells lying in 

 the same bed were placed at very different levels. This small measure explains the modus operandi as well as 

 if the scale had been equal to that of the ancient phenomena under consideration. 



The reader will have perceived in various parts of this work, that while I rejoice in what I would call the 

 " Lyellian method" of testing geological phenomena by modern analogies, I do not believe in the doctrine, 

 that the dislocations of the present day are produced by causes of the same degree of intensity as those of which 

 geology affords the proofs. I must always be of opinion that, although they may belong to the same class, the 

 geological catastrophe (such as the overturning of a mountain chain) and modern earthquake cannot be placed 

 side by side, without our exclaiming " sic parvis componere magna." 



* See observations by Professor Sedgwick and myself on the Eastern Alps, Geol. Trans, vol. iii. p. 415. The 

 bowlders of Hogelpoch were observed by myself in a previous visit, but they form a part of the detritus referred 

 to in our joint memoir. 



