GEOLOGICAL HISTORY OF SERPENTINES. 187 
various groups, as indicated by von Hauer, are as follows: 1. The ancient gneiss and 
granitic rocks, designated by him as the central gneiss; 2. Greenish schistose rocks, de- 
scribed as hornblendic, dioritic and euphotidic, with serpentines, chloritic and tale-schists ; 
3. Saccharoidal limestones, more or less micaceous, with tale-schists; 4. Serpentines, 
euphotide, diorite, and talcose and chloritic schists, as before; 5. A fine-grained gneiss, 
designated as recent gneiss; and 6. Mica-schist, with hornblendic and feldspathic varieties. 
We have evidently here the same great pietre-verdi zone as in the west, comprised between 
the older gneiss and the younger gneiss with its attendant mica-schists. There appears, 
however, a considerable development of crystalline limestones in the midst of the pietre 
verdi. 
§ 61. Further light is thrown upon the question of these crystalline rocks of the Alps 
by the observations of Renevier, Heim and Lory, especially as embodied in an essay by 
the latter on the Western Alps, published in 1878, and in a study of the geology of the 
Simplon, by Renevier, in the same year.* According to Lory, the ancient crystalline 
rocks, designated by him as the primitive schists, as seen in the Simplon, and elsewhere 
in this region, include three groups, in ascending order: Ist. The stage of the gneiss, prop- 
erly so-called, including varieties from the highly feldspathic and massive granitoid 
gneisses to others less feldspathic and more distinctly laminated. 2nd. The stage of the 
mica-schists, often garnetiferous, which embraces, however, alternating beds of gneiss, the 
two rocks passing insensibly the one into the other. These mica-schists, tender, and gray 
in color, are often more or less impregnated with carbonate of lime, and contain bands of 
limestone and marble. 3rd. The stage of the ¢alc-schists, a term which, as Lory explains, 
he uses in a very general sense, to include not only steatites, but talcose, chloritic and horn- 
blendic schists, the latter sometimes without visible feldspar, but often more or less felds- 
pathic, and thus passing into varieties designated by him as talcose, chloritic or horn- 
blendic gneiss. The so-called protogine of the Alps, according to Lory, is but a granitoid 
variety of talcose or chloritic gneiss, subordinate to the tale-schist stage, and passing in- 
sensibly into the talcose and chloritic schists, with which it alternates. It is not, there- 
fore, as some have supposed, the fundamental rock of the Alps, but belongs to an upper 
portion of the primitive schists. The lower gneiss of the Simplon, described by Gerlach 
as the gneiss of Antigorio, to which this distinction apparently belongs, is further noticed 
by Renevier, who assigns to it it a great thickness, and regards it as the basal rock of the 
Alps, corresponding to the ancient gneiss of Gastaldi and the central gneiss of von Hauer. 
The succeeding mica-schists, often garnetiferous and calcareous, with alternating gneiss 
and limestone bands, have also a great volume. The hornblendic schists play a less impor- 
tant part in the series. Though these sometimes contain a little mica, or a little chlorite, 
chloritic schists are rare, and the stage of the talc-schists, indicated by Lory, is not men- 
tioned by Renevier in his description of the Simplon. 
§ 62. The term of primitive schists, as employed by Lory and by Renevier, is not ex- 
tended to the grey lustrous schists, already noticed as forming the upper part of the great 
series included by Gastaldi in the pietre verdi. These upper schists are by Lory regarded 

* Essai sur l’orographie des Alpes occidentales par Charles Lory, p. 76; Paris and Grenoble, 1878. Also, 
Structure géologique du massif du Simplon, etc., par E. Renevier, Bull. de la soc. vandoise des sciences natur- 
elles, vol. xv., No. 79. =“ 
