CENTRAL MASSIVES. 
73 
Lugano is coloured as Gneiss, with the exception 
of three belts — that of Protogine from Wasen to 
Goschenen; of the Secondary strata which constitute 
the Urserenthal, and another Secondary belt forming 
the Bedrettothal, and crossing the Ticino at Airolo 
to the Val Piora. The great Swiss Dufour map 
shows that the stnicture is far from being so simple; 
but in fact no map can adequately show its real 
complexity. The whole tendency of recent researches 
has been to demonstrate that the structure of these 
“central massives” is much more complicated (see 
Fig. 93 p. 76 ) than had been at first supposed— to 
confirm Saussure’s wise saying that “11 u’y a dans 
les Alpes rien de constant que leur variete.” 
In this respect, however, the massives differ con- 
siderably. The structure of Monte Rosa, for Instance, 
is said to be simpler than the St. Gotthard. Indeed, 
the southern Gneisses are, as a general rule, much 
less contorted than that of those in the northern 
massives. 
The strata form more or less lenticular masses, 
and are very varied in composition and structure 
the Gneiss itself presenting many varieties. 
The Gneiss, Granite, Protogine, and even ap- 
parently Mica Schist pass almost imperceptibly into 
one another. “The changes of texture and con- 
