292 PROF. T. G. BONNET ON MESOZOIC ROCKS AND [Aug. 1 894, 



lead-coloured, slaty or slabby, more or less calcareous rock, 1 such as 

 is common elsewhere in the Alps among strata of Jurassic age ; but 

 not a trace is seen of the Altkircho marble, and there is no reason 

 to suspect that it is concealed immediately beneath the water- 

 meadows. 



(d) Section roughly north of Hospenthal. — This is separated from 

 the last by an interval of rather more than a mile. Here the gneiss 

 (much crushed) ends at a height of about 750 feet above the river. 

 Beneath the last outcrop of this rock the ground for about 50 or 60 

 feet vertical is covered ; then begin a number of outcrops of dark, 

 slabby, argillaceous limestone, like that just mentioned, followed at a 

 considerable distance below, where the slope becomes less steep, by 

 the Hospenthal schists. In one place I found projecting from the 

 turf some bits of calcareous rock in a very ' slabby ' condition, paler 

 in colour and more crystalline in aspect than is usual with the 

 indubitably Jurassic rock of the district. Whether it is in situ 

 seemed doubtful, and a small moraine is close at hand. If, however, 

 it be so, and is the marble (as I believe), then there is very little of 

 it, and this is in a very crushed condition. 



(e) Section at Realp. — This is obtained in a ravine od the same 

 side of the valley, which descends near the lower end of the village, 

 at a distance of about 3| miles from the last one. The rocks on 

 the whole are well exposed ; but to obtain a complete section we 

 must cross the torrent, and there are even then three intervals 

 where the ground is covered. The section on the opposite page 

 (fig. 2) indicates the succession of the rocks, and does not require 

 more than a few words of explanation. The marble (fairly well 

 represented) is a very flaggy rock (3), which takes a yellow tinge in 

 weathering. It corresponds under the microscope with the Altkirche 

 marble, and the slice exhibits a very quartzose lamina. It is overlain 

 by a darker variety more like an ordinary limestone (3'). The 

 actual contact of the two cannot be examined, for they are always 

 separated by at least a foot of accumulated debris, but the lower 

 rock seems to become slightly darker in tint as it approaches the 

 upper. Both rocks evidently have been much affected by pressure, 

 and break into slabs which vary in thickness from | inch down- 

 wards, sometimes being not more than | inch thick, almost like 

 slates. 2 The mass between these rocks and the gneiss above is the 

 usual dark lead-coloured limestone, interbanded with dark phyllites ; 

 that between these and the Hospenthal schists below consists of 



1 The rock is quarried for a good part of the way. Specimens have been 

 examined with the microscope : one is slightly more crystalline than usual (it 

 was selected for this reason), but is very different from the marble. 



2 The microscopic structure of this rock presents difficulties, which will be 

 more fully considered in dealing with the sections on the Furka Pass. It may 

 be a crushed and stained condition of the marble, but it may be only a rather 

 exceptional variety of the Jurassic limestone, and one or two grains show a 

 structure that is possibly of organic origin. 



