M. Elie de Beaumont ow the Relative Age of Mountains. 301 



tention whatever of searching into the causes of the violent and 

 transient phenomena which produced the different cataclysms- 

 The questions which he has proposed to himself to solve, are 

 questions of epochs and of coincidences of dates. 



The results at which he has arrived with respect to the 

 epochs at which several systems of mountains received the prin- 

 cipal features of their present form, ai'e entirely independent of 

 all hypothesis respecting the manner in which they have received 

 that form. Admitting his results, one remains free to choose 

 between the hypothesis of Deluc, who explained the raising of 

 the strata by the sinking of a part of the earth's crust, and the 

 hypothesis generally adopted by the most celebrated geologists 

 of our epoch, and which consists in supposing that the secondary 

 strata which are found raised in the mountain chains, have been 

 thus elevated by the heaving up of masses of primitive rocks, 

 which generally constitute their central axis and principal sum- 

 mits. 



The coincidences of dates which the author thinks he has dis- 

 covered are the following : — 



1. In a small syst-^m of mountains of which the Erzgebirge in 

 Saxony, the Cote-d'Or in Bourgogne, and Mount Pilasin Tores, 

 form part, the raising of the strata has taken place at the epoch 

 which has separated the period of the deposition of the Jura for- 

 mation from that of the deposition of the greensand and chalk- 



2. In a system of which the Pyrenees and Appenines form 

 part, the raising of the strata has taken place at the epoch which 

 saw the chalk deposite ended, and which was followed by the 

 period of the deposition of the tertiary formations. 



3. In the western part of the Alps, the raising of the strata 

 has taken place at the epoch in which the tertiary formations 

 were ended, and which preceded that of the deposites called 

 transported, rolled, diluvial or alluvial. 



4. A new revolution interrupted the deposition of these for- 

 mations, leaving, as traces of its passage, the large alpine blocks 

 transported to the Jura mountains, and the pebbles of the Crau, 

 and this revolution has probably corresponded to the formation 

 of certain fractures which cut up the ground in Provence, and to 

 which is owing the existence of the mountamsof Leberon, Sainte 

 Baume, &c. ; a system with which it is not impossible that the 



JULY OCTOBER ISJ^Q- X 



