liv PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



the same level. Surely such a break in the continuity of a fauna so 

 nearly identical in its parts, should of itself induce us to pause be- 

 fore we accept this theory, however ably constructed ; and further, 

 can we imagine that this vast interval, during which the whole 

 of Switzerland was depressed more than 9000 feet, and then again 

 uplifted at successive intervals, should have left no traces of inter- 

 mediate formations other than ordinary drift ? Nor can we avoid 

 observing, that the general configuration of the land, including the 

 valley of Geneva and its Lake, having been produced before the sup- 

 posed final depression and elevation of the Alps, the sea-action 

 during any one of the steps of rise would be insufiScient to explain 

 the passage of boulders, or their deposits, at high levels on the Jura, 

 without the intervention of ice, which it is the object of the paper to 

 dispense with. The sudden elevation of a large mass of land or 

 water would doubtless produce a great wave, proceeding in all direc- 

 tions from the centre of the disturbed mass outwards, as the water 

 would at first be partially carried up with it, and then roll back, ac- 

 quiring velocity in proportion to its height ; but, as that velocity 

 would be very small at first, the action would be small also, and no 

 uniformly polished surface could be produced ; and, as regards the 

 portion of water not participating in the motion, little effect could be 

 produced ; as, for example, while the mass was raised 1500 feet, or the 

 space between the lines of 9000 feet and 7500 feet, the Molasse of 

 the Swiss basin must have been covered by 6000 feet of water, and 

 therefore have been secured from any dynamical disturbance conse- 

 quent on the addition of water to its surface ; the results of the over- 

 flowing water being made manifest in regions far distant from the 

 limits of the basin rather than on its own bottom. On the actual 

 line of a sea-level the effect could have been little more than 

 that of loosening materials, which would then roll down into the 

 waters below, following the wave, and not preceding it, just as is the 

 case with the stones and gravel on the sea-shore as they roll down 

 after the receding tidal wave ; and it is difficult to conceive that 

 any sufficient velocity could be bestowed upon a rocky mass by such 

 a process as to have transported it to any great distance, surely not 

 more than it would have acquired by moving freely through space for 

 the same vertical distance. 



Such problems are of surpassing difficulty, and assuredly require 

 long and patient study for their solution ; nor should it be forgotten 

 that the action of the sea is by no means so powerful in producing 

 effects such as are here supposed. Very friable strata are certainly 

 much worn ; but on the rocky shores of the Mediterranean the line 

 of water-level is rather shown by growth of seaweed than by erosion ; 

 where, however, the water is aided by Httoral tidal action, and bears 

 along with it sand and gravel, erosion is sometimes very striking ; 

 though the ordinary wear by wave-action is very irregular, some 

 portions of less cohesion givmg way before others, and the general 

 result being the formation first of caverns and then of bays, the harder 

 portions remaining as projecting capes or promontories. Around a 

 small island this action would be more continuous and less varied, 



