THE 
AMERICAN NATURALIST. 
VoL. xvu.— NOVEMBER, 1883.—No. 11. 
THE PRE-CAMBRIAN ROCKS OF THE ALPS? 
BY T. STERRY HUNT, LL.D, F.R.S. 
HE writer began by reviewing the history of Alpine geology, 
and noticed first that speculative period when the crystalline 
rocks of the Alps, including gneisses, hornblendic and micaceous 
Schists, euphotides, serpentines, etc., were looked upon as altered 
sedimentary strata of Carboniferous or more recent times. He 
then traced the steps by which these views have been discarded, 
and more and more of the rocks shown to belong to EoZ0ic or 
Pre-Cambrian ages. In this connection the labors of von Hauer, 
Gerlach, Heim, Favre, Renevier, Lory, Gastaldi and others were 
analyzed, and reference was made to the great progress since the 
Saj in 1872, published a review of Favre on the geology of the 
Ips. i 
The sections by Neri, Gerlach and Gastaldi in the Western, and 
those of von Hauer in the Eastern Alps were described, arq it 
was shown that all these agree in establishing in the crystalline 
Tocks four great divisions in ascending order: 1st. The older 
Sranitoid gneiss with crystalline limestones, graphite, etc., referred 
by Gastaldi to the Laurentian. 2d. The so-called pietre verdi, oF 
Sreenstone group, consisting chiefly of dioritic, chloritic, steatiti¢ 
and epidotic rocks, with euphotides and serpentines, including 
~ °° talcose gneisses, limestones and dolomites, and regarded by 
Staldi as Huronian. 3d. The so-called recent gneisses of yon 
Bas and Gastaldi, interstratified with and passing into granu- 
ites and micaceous and hornblendic schists, also with serpentines 
and crystalline limestones. 4th. The series of argillites and soft 
Blossy Schists with quartzites and detrital sandstones, including 
Read at the Minneapolis meeting of Amer. Assoc. Adv. of Science, Aug» 1883 
x 
VOL, 
XVIL—No. cr, 73 
