374 A OTLLORS ABS TRA CAS) 
age with older post-Carboniferous, probably also Mesozoic, amphibo- 
lite schists. The latter are in places impregnated with slightly aurif- 
erous iron pyrites, forming belts or fah/bands. ‘The deposits are typ- 
ical fissure veins forming two systems, one with a west-northwest strike, 
the other with a northeast strike; all fissures dip southeast or southwest 
at angles ranging from 20° to 80°. The vein filling is principally quartz, 
with very little calcite. Native argentiferous gold, with small quanti- 
ties of auriferous and argentiferous sulphides comprise the ores. The 
richest ore is usually concentrated in chutes, mostly of elongated form 
and dipping east on the plane of the vein. In the amphibolite a dis- 
tinct connection may frequently be noted between the fahdbands and 
the pay chutes on the veins crossing them. Next to the veins the 
country rock is altered by replacement to a mixture of carbonates, 
sericite and iron pyrites. This process, to which nearly all deposits 
of the gold belt are subject, is illustrated by several analyses. 
The fissure systems have in all probability been formed simultane- 
ously by a compressive stress acting in a direction parallel to the trend 
of the Sierra, and the fissuring was attended with considerable hori- 
zontal motion. Hot siliceous and carbonated solutions containing 
heavy metals dissolved in alkaline sulphides ascended the veins, alter- 
ing the wall rock and depositing the silica and ores in the largely open 
fissures. Action of percolating surface waters seems out of the ques- 
tion. The auriferous iron pyrites of the fah/éands were probably a 
source of local enriching of the veins, but the derivation of the largest 
part of the precious metals must as yet be considered an open ques- 
tion. A map of the vein systems accompanies the paper. 
Ueber das Norian oder Oberlaurentian von Canada. By Frank D. 
ApvaMs. Veues Jahrbuch fiir Min, etc., Beil. Bd. VIII., 1893. 
The author having in a former paper shown that the great 
anorthosite masses supposed by the earlier Canadian geologists to 
form the upper portion of the Laurentian system, are in reality great 
igneous intrusions, proceeds in the present article to give an account 
of a large area of the typical Laurentian to the north of Montreal, in 
which he deals principally with the petrological character, strati- 
graphical relation and origin of the Grenville series, which is the true 
upper portion of the Laurentian. The lower or fundamental gneiss in 
its uniform character, as well as in its mineralogical and chemical 
