Geological Society of London. 41 
These journeys were undertaken in the summer of 1887 in the 
company'of the Rev. H. Hill, F.G.S., in order to ascertain whether 
the apparent stratigraphical succession among the gneisses and 
crystalline schists which the author had observed in the more central 
region of the Alps, held good also in the Western and Eastern Alps. 
At the same time all circumstances which seemed to throw any light 
on the origin of the schists were carefully noted. The author 
examined the rocks along two lines of section :—(1) By the road 
of the Col du Lautaret from Grenoble to Briancon, and thence by 
the Mont Genévre and the Col de Sestriéres to Pinerolo, on the 
margin of the plain of Piedmont. (2) From Lienz, on the upper 
waters of the Drave, to Kitzbuhel; besides examining other parts 
of the central range, east of the Brenner Pass. The specimens 
collected have subsequently been examined microscopically. 
The results of the author’s investigations may be briefly sum- 
marized as follows :— 
(1) While rocks of igneous origin occur at all horizons among the 
crystalline series of the Alps, these, as a rule, can be distinguished ; 
or, at any rate, even if the crystalline schists in some cases are only 
modified igneous rocks, these are associated with recognizable 
igneous rocks of later date. 
(2) There are, speaking in general terms, three great rock-groups 
in the Alps which simulate curiously, if they do not indicate strati- 
graphical sequence. The lowest and oldest resemble the gneisses 
of the Laurentian series; the next, those rather “friable” gneisses 
and schists called by Dr. Sterry Hunt the Montalban series; the 
third and uppermost is a great group of schists, generally rather 
fine-grained, micaceous, chloritic, epidotic, calcareous and quartzose, 
passing occasionally into crystalline limestones, and (more rarely) 
into schistose quartzites. 
(3) The Pietra Verde group of Dr. Sterry Hunt, so far as the 
author has been able to ascertain, consists mainly of modified igneous 
rocks, of indeterminable date, and is at most only of local, if, indeed, 
it be of any classificatory value. 
(4) Of the above three groups the uppermost has an immense 
development in the Italian Alps and in the Tyrol, north and south 
of the central range. It can, in fact, be traced, apparently at the top 
of the crystalline succession, from one end of the Alpine chain to the 
other. 
(5) The middle group is not seldom either imperfectly developed 
or even wanting, appearing as if cut out by denudation. It was not 
seen in the traverse of the Franco-Italian Alps, except perhaps for a 
comparatively short distance on the eastern side, being probably 
concealed by Palaeozoic and Mesozoic rocks on the western side. It 
is not very completely developed in the Eastern Tyrol, and seems to 
prevail especially in the Lepontine Alps, and on the southern side of 
the watershed. 
(6) The lowest group is fairly well exposed, both in the French 
Alps and in the Central Tyrol. 
(7) Asa rule, the schists of the uppermost group had a sedimen- 
