238 
SCENERY OF SWITZERLAND. 
The Bernina. 
Tlie Bernina is not a comparatively simple central 
mass like that of Mont Blanc, where we find a com- 
pact crystalline nucleus with well-marked fan-struc- 
ture. It is rather a complex mass of semi-detached 
bosses, which were long supposed to consist through- 
out of crystalline rocks; but more complete study 
has shown that these are only a mantle, covering a 
central mass of plutonic origin, and itself once covered 
by sedimentary deposits. 
The so-called fan-structure can be traced, but is 
not well marked.* 
The Bernina Pass itself has long attracted atten- 
tion as having no true watershed. The flat summit 
is occupied by four small lakes, at a height of 
22 20 metres, from the uppermost of which in wet 
weather the water often runs out at both ends north- 
wards to the Inn, and consequently to the Black Sea; 
southwards to the Poschiavina and the Adriatic. 
I'he valley of Pontresina, according to Theobald, 
is (Fig. 150) a synclinal between two masses of Granite 
and Syenite. 
'I’he Inn is a river which has been deprived of 
its original source. In most cases as we pass up a 
* Theobald, Beitr. z. Geol. K. d. Sch-w., L. m. 
