at the Junction of Sien'de with Dolomite. 127 



hill called Canzocoli, forming a lump or projection at the foot 

 of the mountain ridge which bounds the valley of Lavis on the 

 west. This valley communicates with the -valley of Fassa, 

 or rather constitutes its lower portion, or embouchure into 

 the vale of the Adige, and the immediate spot in question is 

 about half a mile from the village of Predazzo, a spot already 

 remarkable among geologists from the asserted superposition 

 of granite on chalk, an account of which is to be found in a 

 late Number of the Edinburgh Philosophical Journal, but 

 whose true nature will perhaps be better understood from 

 what follows. 



Predazzo itself stands on the borders of a district of fine 

 red granite, perfectly well characterized, but which gives place 

 to a compound of felspar and mica, unaccompanied (so far as 

 I could discern) by quartz, of which (4) is a characteristic 

 specimen,* and which itself passes into a close grained rock, 

 in which the crystalline structure is much less perceptible (3.) 

 The transition is sudden, and is perfectly well seen in the 

 specimen (4). These are from the mountains (Monte Mu- 

 lazzo) on the opposite side of the valley. 



Immediately above Canzocoli, the rock (which for brevity 

 I shall term Sienite, without pretending to decide whether it is 

 entitled to that appellation or not) is a crystalline compound, 

 containing abundance of felspar and dark-coloured mica, per- 

 haps also hornblende, and possibly experienced eyes may de- 

 tect in it quartz. 1, 5, 6, 7, 8, are specimens of this rock, 

 (1) and (8) being characteristic of the general mass, the others 

 having peculiarities to be noticed presently. Along the sum- 

 mit of the ridge runs a crest of dolomite reposing on the cry- 

 stalline rock, the line of junction being nearly horizontal, but 

 about a furlong south of Canzocoli this line suddenly changes 

 its direction, and descends the mountain in a curve which is 

 at first nearly vertical, but soon inclines backwards, (or to the 

 north,) and descends obliquely to the point where it intersects 

 the most northern summit of the little mound to which the 

 name Canzocoli is appropriated. Accordingly, in all the in- 

 terval from the place of its vertical direction, the dolomite 

 distinctly underlies the sienitic rock. The junction, however, 



* The specimens referred to arc deposited in the collection of the Geo- 

 logical Society of Loudon. 



