ANNIVEESAET ADDRESS OF THE PRESIDENT. 7.7 



between W.N.W. and W., dipping at various angles (not high) on 

 the southern side. To this succeeds a rather less fissile gneiss (which 

 weathers a lighter colour), the dip here being about oO"^ E.S.E. ; then 

 comes a coarser and still less micaceous gneiss, which, however, after 

 a time reverts to much the same type as above. Just above Taverne 

 the dip is high to the east. From this place to the neighbourhood of 

 Lugano road-sections are wanting. iS'ear the railway station of that 

 town highly fissile schists are seen in cuttings. These exhibit a 

 cleavage-foliation, which makes a high angle with the bedding, the 

 latter being indicated by a band of quartzose rock about 20 feet thick. 

 This dips roughly to S. at about '^0° ; the cleavage-foliation dipping 

 at about 40° between N.N.E. and IS". The " papery " mica-schist 

 reminded me much of that on the Lukmanier road near Dissentis, 

 and I find it is referred by the Swiss geologists to the same group, 

 the Casanna schists. South of Lugano as far as Morcote, similar 

 but less fissile mica-schists are exposed at intervals by the lake side 

 beneath the Triassic strata, and are cut by felstones. These also 

 are referred to the Casanna group, except that at the latter place 

 they are included in the mica-gneiss, like those above Taverne. In 

 short, if we omit the brown-bedded scliists and certain considerable 

 masses, which may be crushed granites, the greater part of the section 

 from Olivone southwards, till the crystalline rocks are lost beneath 

 the southern fringe of ITesozoic and later beds, consists of micaceous 

 gneisses or mica-schists, which I should regard, at any rate in 

 part, as belonging to the Lepontine group; and this section is 

 in accordance with what I have observed in other neighbouring 

 districts. 



I have been obliged to describe this traverse of the Alps at what 

 may seem an unreasonable length, because T cannot otherwise im- 

 press upon you how strongly the evidence, both in the field and in 

 my subsequent examination of specimens, is favourable to a definite 

 succession from the mica-gneiss up to the brown-bedded schists, and 

 to the existence of an earlier foliation, connected with some kind of 

 stratification, and of a later cleavage -foliation which is sometimes less, 

 sometimes more conspicuous, than the other. I shall pass more 

 rapidly over the evidence aff'orded by the districts further west. 

 In the sections which I have examined on the Simplon road I agree 

 with Professor Eenevier in considering the coarse gneiss (called by 

 him Antigorio gneiss, and exposed in the grand cliff's of the gorge 

 of Gondo) as the most ancient rock. This is overlain by gneiss and 

 mica-schists, and in the lower part of the latter group we find the 

 following succession: — (1) fairly coarse gneiss, (2) crystalline lime- 

 stone about 4 feet, passing into calc-mica schist, about 2 feet, 

 followed by dark mica-schist. In (2) are sparse lines of a dark 

 mica parallel with the apparent stratification, which dips roughly 

 30^ W.X.W. The southern slopes of the Simplon Pass, and a part 

 of the descent on the northern side, are formed of bedded gneisses 

 and mica-schists, probably folded and faulted together in such a way 

 that it will be no easy task to unravel the true stratigraphy of the 

 mass. The Swiss geological map places a long axis of gneiss, of 



