and Writings of Baron Leopold von Buck. 225 



Many other difficulties have been raised as to Buch's view 

 of the origin of dolomite, and these have been strongly urged 

 by English geologists. The chief ground of this opposition 

 has been, that in England there is a formation that occurs re- 

 gularly in a determinate order of stratification, which consists 

 chiefly of dolomite (dolomitic limestone), but partly also of 

 common limestone, and which bears the name of magnesian 

 limestone. The application of Buch's ideas to this case is at- 

 tended with many obstacles.* 



The chemists, likewise, and particularly Berzelius, have 

 maintained, that the conversion of limestone into dolomite 

 could not have taken place in this way, because magnesia, 

 according to all the experiments that have been made, can 

 not be sublimed ; but here we ought to consider that the con- 

 ditions of this phenomena cannot be imitated in laboratories, 

 and that we ought not to regard as impossible what has not 

 succeeded there. 



Finally, the discovery has been made in various parts of 

 France and Germany, that in the midst of distinctly stratified, 

 regularly formed limestones (as in the Muschelkalk), whole 

 stratified masses occur which consist chiefly of dolomite. 

 Had these limestone-formations been affected by the penetra- 

 tion of hot vapours, in consequence of proximity to any volca- 

 nic rock, the pure limestones would have been converted into, 

 granular marble, and the magnesian limestones into crystalline 

 dolomite ; that such is really the case, follows clearly from the 

 examination of many marble rocks, in which granular marble 

 and dolomite almost always occur together, and united with 

 each other in such a manner that we can be in no doubt as 

 to their similar origin. An excellent example of such appear- 

 ances is afforded by the celebrated marble quarries of Carrara.-|* 



Although these discoveries of Von Buch, and the views 

 founded on them, have not been found susceptible of that ge- 



* Some geologists are inclined to draw a line of distinction, as to origin, 

 between the dolomites of the Alps, &c. and the magnesian limestones of 

 England, &c., just as they would also separate the gypsums of the Val Co.- 

 nana, and other similar localities, from the gypsum of tlie Paris basin, &c. 

 —Edit. 



t See Professer Hoffmonu's paper in this Journal, vol. xxi. p. 116.— Edit. 



