ANls^IVEESAEY ADDRESS OF THE PRESIDEXT. 7 5 



two of these localities are more than three miles apart in a straight 

 line : from Santa Maria to the exposures between the Lago de 

 Ritom and the Lago de Cadogna is quite five miles ; and from the 

 former lake to the Gries Pass is about fifteen miles — that is to say, 

 this peculiar rock abounds, to my knowledge, at three localities in 

 the line of the general strike of the district, the extremes of which 

 are more than twenty miles apart, and at two localities, the com- 

 ponent of whose distance, measured across the strike, is full two 

 miles, if not more. But this is not all. In descending the Luk- 

 manier Pass towards Olivone we again meet with this peculiar 

 melanite schist, overlying various mica-schists, some garnet-bearing, 

 some containing staurolite or kyanite, together with quartz- schists 

 and quartzites, the group recalling in several respects the one 

 already noted as occurring on the right bank of Lake Eitom. As in 

 that neighbourhood, so here, the mode in which these rocks, so dif- 

 ferent in mineral character, are interstratified and associated, both on 

 a large scale and on a small, seems to me inexplicable, unless it be 

 the result of stratification. They exhibit stratification-foliation, and 

 have obviously been subsequently subjected to great pressure. This, 

 in some cases, has flattened out the foliated bands, as if (to use a 

 very homely simile) a rolling-pin had been passed over layers of 

 tough paste alternating with "jam;" in others has forced them 

 into crumples and zigzags of every possible kind, and has often 

 developed a secondary cleavage- foliation, this last being quite in- 

 dependent of the first one (figs. 1, 2, p. 97). The evidence in favour 

 of these conclusions is, to my mind, overwhelming. Excellent 

 sections are exposed again and again by the roadside for a distance 

 of perhaps a couple of leagues. 



Gneiss resembling that described above reappears on the right 

 bank of the Yal Campra, and is traversed by the long sweeps of the 

 new diligence-road leading to Olivone. In the Yal Grigna, how- 

 ever, which descends from the north to join the Yal Campra at this 

 town, and initiate the Yal Blegno, we again come upon the great 

 series of brown-banded schists, though here the melanite schist does 

 not appear to be well developed. But the lower part of the Yal 

 Grigna, a narrow picturesque glen, cuts through a huge mass of a 

 quartzose rock, sometimes calcareous, interlaminated and inter- 

 banded with mica-schist, generally rather dark, often exhibiting 

 a very distinct secondary or cleavage-foliation, as well as one cor- 

 responding with the bedding. Of one westerly extension of this 

 mass I have already spoken, but I may add that in the neighbour- 

 hood of and below the village of Binn in the Binnenthal, where it 

 is admirably exposed, it still preserves its main characteristics. A 

 little above the latter village, apparently low down in the series, is 

 a thick band of white crystalline dolomitic limestone. Further, in 

 the cliff's of the Hohsandhorn, to the north of a glacier pass leading, 

 by the north side of the Ofenhorn, from the Tosa Palls to Binn, we 

 see the following section : — (1) a strong gneiss, rather markedly 

 banded *, (2) a zone of the dark-bedded schists, (3) the crystalline 

 * This I examined at the top of the pass. 



