ANNIVERSARY ADDRESS OF THE PRESIDENT. xHx 



of dislocation, each chronologically distinct from the other, can be 

 made out*. 



In regard to the Alps, it appears from the observations of Leo- 

 pold Von Buch, Sir Roderick Murchison, and others, that whatever 

 be the major axis of the crystalline mass in the centre, such also is 

 the prevailing direction of all the sedimentary deposits which lie on 

 either side of the chain. Whether the axis be composed of gra- 

 nite, syenite, gneiss, mica-schist, marble, dolomite, or of any rock 

 formed by eruption or by the metamorphism of pre-existing strata, 

 there is obviously some connection between the position of the cen- 

 tral crystalline nucleus and the dominant strike of the flanking de- 

 posits. It is as if the intrusion of the igneous matter at certain periods 

 had not only raised the chain, but so injected and distended its cen- 

 tral parts, as to force outwards the pliant strata on each side, and to 

 cause them to fold themselves into parallel anticlinal and synclinal 

 flexures. 



The theory first proposed by Von Buch, of the conversion of 

 mountain masses in the Tyrol and other parts of the Alps into dolo- 

 mite, and of other limestones into gypsum, has been gradually em- 

 braced by the majority of the most eminent geologists who have 

 carefully examined the great chain. The porous and cavernous 

 nature of the dolomite are referred to by MM. E. de Beaumont and 

 Morlot as a character implying the alteration of a compact rock into 

 one of more open texture which had been permeated by gasesf . " It 

 is now more than twenty years," says De Beaumont, writing in 1847, 

 " since I first advocated Leopold Von Buch's views, who attributed 

 the gypsums and dolomites of the Alps to epigenie, or to the altera- 

 tions of calcareous masses by mineral springs and gaseous emana- 

 tions which came up from the interior of the earth at the time when 

 the porphyries called melaphyre were formed J. M. FrapoUi, in re- 

 ference to similar metamorphic action, has adduced numerous facts 

 illustrative of the manner in which carbonates of lime may have been 

 turned by sulphurous vapours into gypsum ; and Sir R. Murchison 

 reminds us that the well-known thermal waters of Aix do now ac- 

 tually change the ordinary Jurassic limestone into sulphate of lime ; 

 while, according to M. Coquand, another example of the like metamor- 



* BuUetin, 2nd Series, vol. iv. p. 1368. 



t Ibid. vol. vi. p. 318. % Ibid. vol. iv. p. 1282. 



