402 Prof. T. G. Bonney— 



pebbles, though not often, in the quartz-schist near Zinal. Time 

 will be saved by collecting together the results of our examination 

 of the different sections. 



This quartz-schist, according to the Geological Survey Map of 

 Switzerland (Blatt. xvii and xxii), occurs in several localities 

 on either side of the Val d'Anniviers, coming generally immediately 

 above the Casanna Schiefer. It is overlain by a thick mass of 

 schist, which for brevity I will designate calc-mica-schist, 1 though 

 it may vary from an almost pure marble (rare) to a very slightly 

 calcareous mica-schist ; the latter being the more usual type in this 

 valley. With these schists we find a third type, called on the map 

 Griiner Schiefer, which may be an intrusive igneous rock, subse- 

 quently modified by pressure. As there shown, the quartz-schist 

 strikes, very roughly speaking, from ENE. to WSW. In the 

 lower part of the Val d'Anniviers it is dipping at a moderate angle 

 towards the south, 2 and its outcrop rises rather rapidly up the 

 mountain slopes on either side. Proceeding along the crests of 

 these towards the same point of the compass, we see from the map 

 that the quartz-schist occurs at intervals above the Casanna Schiefer, 

 at elevations varying approximately from 8,800 to 9,800 feet above 

 the sea. Presently, in the peaks of the Tounot and Hoc de Budry 

 (10,302') on the east side, and in the Bees de Bosson (10,3Sft') on 

 the west, it is capped by calc-schist. Then, south of the former, 

 comes a slight interruption, for the Forcletta Pass (9,810') is cut 

 down to the Casanna Schiefer, and the calc-mica-schist, as the crest 

 rises again, seems to rest for a short distance on this rock. 3 But 

 the quartz-schist soon reappears at the base of the Diablons 

 (11,850'), in its usual position, and thence descends towards the 

 valley, disappearing at last beneath talus at some height above 

 Zinal. On the western side of the Yal d'Anniviers the quartz- 

 schist, in a like position, runs southward from the Bees de Bosson, 

 sweeps round the head of the Val de Moiry (a tributary of the 

 main valley), passes along the flanks of the Corne de Sorebois 

 (9,207') — where it is capped by a fair thickness of the calc-mica-schist 

 (very micaceous) — and then descends, reaching the bed of the 

 valley opposite to Zinal, where it is well exposed. These facts 

 seem to me explicable only on the hypothesis that the Casanna 

 Schiefer, the quartz-schist and the calc-mica-schist, with the associated 

 Griiner Schiefer, form part of a huge fold, the axis of which slopes 

 up towards the north at a moderate angle. This, at first sight, 



1 It is called Glanz Schiefer (schistes lustres) on Blatt xvii, and Grave Schiefer, 

 Jcalkhaltig, on Blatt xxii. On the former its place in the table of colours seems 

 to make it newer than the Carboniferous, but on the latter it is the older rock. 

 So far as regards the calcareous and micaceous schists which are associated with 

 the quartz -schist, I have no doubt that the whole group is pre-Carboniferous ; but 

 the other map appears to me to designate by the same tint two rocks which differ 

 in locality, lithological characters, and geological age. 



2 I intended to make an exact measurement as I came down the valley, but was 

 hurried by the on-coming of a heavy shower. 



3 I have not examined this part, so cannot say whether the quartz-schist is absent 

 or the outcrop is too thin to be indicated on the map. 



