146 M. Stud or on the Geological Structure af the Alps. 



the Alps. We are able, however, to recognise six principal 

 masses or groups in the portion which is more immediately in 

 our neighbourhood : — 



1. Ttie group of Mont Blanc^ stretching from the Col du 

 Bonhomme to Salion in the Valais, and limited by the valleys 

 of Chamouny and of Entreves. 



2. The group of the Aiguilles Bouges, situated more to the 

 north, commencing near Servoz, and terminating near Lavey, 

 above the Betit de Morales. 



3. The group of the Bent-Blanche^ which rises from the bot- 

 tom of the Val d^Annivier, attains its culminating point in 

 the peak called the Bent Blanche, and is prolonged obliquely 

 through the middle of the valley of St Nicholas towards the 

 Simplon. 



4. The group of Mont-Bosa^ which lies to the east of the 

 last, and stretches towards the southern portion of the Simp- 

 lon, and probably also into the Canton Tessin. 



5. The group of St Gothard, extending from the Upper 

 V^alais to the vicinity of Trons in the valley of the Vorder 

 Rhine on the north, and bounded on the south by the valley 

 of Airolo. 



0. Tlie group of the Finsteraarhorn^ the largest of all, and 

 that which exercises the most preponderating influence on the 

 relief oi the surface of Switzerland. The pass of the Gemmi 

 and that of Kisten to the east of the Todi, may be regarded as 

 its extreme limits. The Col of the Grimsel, from Imgrund 

 to Obergestelen, and the road of the St Gothard from Amsteg 

 to Urseren, traverse it in its whole breadth. The vicinity of 

 the group of St Gothard, and the distance of the other groups, 

 produce the remarkable symmetry of the Swiss Alps to the 

 east and west of the St Gothard. 



Mica-slate, gneiss, granite, ^c. — The groups just enumerated 

 are remarkable, not only on account of the immense glaciers 

 which they feed, and whose study has acquiredsuch interestfrom 

 the labours of Charpentier and Agassiz, but also from the nature 

 and structure of their rocks. Their principal mass is com- 

 posed of rocks formerly called primitive, viz. of mica-slate, of 

 gneiss, of protogine, and of gneissitic granite. The direction 

 of tlie beds, which are generally highly inclined, is conform- 



