1100 The Pre-Cambrian Rocks of the Alps. (November, 
also beds of serpentine with talc, gypsum, karstenite, dolomite 
and much crystalline limestone. This fourth series, well seen at 
the Mont Cenis tunnel, is still claimed by Lory and some others 
as altered trias, but the present writer’s view, put forth in 1872, 
that it is, like the preceding groups, of eozoic age, was subse- 
quently accepted by Favre, and by Gastaldi, and is now estab- 
lished by many observations. To this horizon belong the crys 
talline limestones of the Apuan Alps, including the marbles of 
Carrara. 
The writer next recalls the fact that he, in 1870, insisted upon 
the existence of a younger series of gneisses in North America, 
alike in the Atlantic States, in Ontario, and to the north-west of 
Lake Superior. These, in his address before the American Asso- 
ciation for the Advancement of Science in 1871, he farther de- 
scribed under the name of the White Mountain series, and sub- 
sequently in the same year, called them Montalban. These rocks 
were then declared to be younger than the Huronian, and to 
overlie it, though in the absence of this latter it was pointed out 
that in Ontario and in Newfoundland the Montalban reposes u- 
conformably upon the Laurentian. When these newer gneiss 
and mica-schists were first described in 1870, there was included 
with them an overlying group of argillites, quartzites and crys 
talline limestones, and for the whole the name of Terranovan ag 
suggested provisionally ; but in defining in the following year the 
White Mountain series, this upper group was omitted, and. ia 
subsequently referred to the Taconian series, the Lower Taconic 
of Emmons, and the so-called altered Primal and Auroral of H. 
D. Rogers, in Eastern Pennsylvania. T 
The writer next described his own observations in the Alps : 
and the Apennines in 1881. He affirms the correctness of aa , 
taldi in referring the groups one and two to Laurentian # 
Huronian, finds the third, or the younger gneiss and mica-s¢ 
group of the Alps, indistinguishable from the Moita ee | 
regards the fourth as the representative of the American i 
nian. It was maintained by Gastaldi that these pre- ‘orthes® a 
groups of the Alps underlie directly the newer rocks of N l a : 
and Central Italy, forming the skeleton of the apeiti aae : 
pearing in Calabria, and moreover protruding in various OY a 
in Liguria, Tuscany and elsewhere. The serpentines, euph m 
and other resisting rocks thus exposed have been regarded ee) 
