MEDLICOTT — ALPS AND HTMALAYAS. 37 



SO peculiar a process. The united efforts of expansion and gravitation 

 seem to me unequal to the task. Is it not absolutely certain that any 

 natural lateral force in the shell of our globe can be neither more 

 nor less than a component of gravitation — of the centripetal force, — 

 and thus that any consequent compression must indicate a total re- 

 sult in the same direction ? I cannot pretend to s^^cak with any 

 authority on a question of pure mechanics ; nor do I, in using the 

 "word " supernatural " attempt to dictate the impossible ; it is, 

 however, a maxim that definite scientific speculation should keep 

 within sight of ascertained facts. The accepted interpretations of 

 Alpine sections seem to me to transgress this maxim. I hr ve not 

 found any very circumstantial explanation of the upheaval appealed 

 to in those accounts ; but the alleged result seems to me to necessitate 

 the conception of this mountain-mass as of a very acute wedge, dis- 

 continuous from the enclosing matter (like the bung in a barrel), 

 driven outwards — not by any general expansive force, for such must 

 act with equal or greater effect upon the contiguoas matter, which 

 (not being hooped down) would rise rather than be compressed, 

 but by some peculiar force aeting only on the wedge. The onus of 

 discovering such a force must rest with those who have evoked it. 

 I would rather suggest that these features of conio tion be taken only 

 for what thej j)rhnd facie imply — the sinldng of the mountc^in -mass. 

 Subsidence, or at least shrinkage, as exhibited by the compression 

 of strata, is seen in every region of the earth. In these matters 

 geologists seem to have retrograded from the views of Deiuc and 

 other early fathers of the science*. 



Actual observation has placed beyond doubt the fact of small, but 

 rapid, elevation of large areas of the earth's surface. Long- cor tinned 

 slow rising is also an established fact. It is fortanate we have 

 this information; for it were difficult to say what coald be the posi- 

 tive stratigraphical evidences of upheaval. The burst-bubble per- 

 formance, which is so largely accepted as accounting for the structure 

 in the central regions of the Alps, is quite at variance mth all we 

 know of natural phenomena. As evidence of actual upheava"", the 

 presence of marine deposits above the sea-level is, generally speaking, 

 indisputablef. With reference to deposits not marine, a large correc- 

 tion must, however, be introduced into Alpine geology. The recently 

 recognized power of rain and rivers to form extensive deposits at 

 any level will no doubt remove the necessity for much of the pro- 

 digious rising and sinking hitherto demanded to account for such 

 non-marine deposits, both in Posttertiary times and during the 

 Molasse period. 



* Bull, Soc. Geol. France, 2^ ser. vol. vii. p. 54. 



t The assumption of the absolute permanence of tlie sea-level (that its level 

 has permanently maintained the same radial distance from the centre of the 

 earth) has quietly taken the position almost of a postulate in geological induc- 

 tion. The notion is inconsistent with any progressionist doctrine, essentially 

 so with Laplace's theory. A very grave obstruction may thus be introduced 

 into the discussion of questions where very remote conditions may be concerned, 

 as in this question of mountain-structure. 



