198 cruise of the neptune 
probably include areas of Huronian. Jameson mentions as 
among the prominent varieties of rocks derived from this 
region, " Granite, gneiss, mica-slate, clay-slate, chlorite-slate, 
primitive-trap, serpentine, limestone and porphyry." In asso- 
ciation with these the following minerals occur: "Zircon and 
beryl, also precious garnet, actinolite, tremolite, diallage, cocco- 
lite, rock crystal, calc-spar, rhomb-spar, asbestos, graphite or 
black lead, specular iron ore, magnetic iron ore, chromic ore or 
chromate of iron, titanic iron, common and magnetic iron 
pyrites." Some of the " transition rocks " noticed by Jameson 
should probably also be classed with the Archaean, and in addi- 
tion to several of the minerals above mentioned, in these were 
found tourmaline (schorl) and molybdenite.' 
The coast between the mouth of Chesterfield inlet and 
Churchill, was examined by Tyrrell, and the following sum- 
mary of the geology is taken from his report : - 
' On the low flat shores of Hudson bay between Seal river and 
Cape Esquimaux few rock exposures occur, but those seen con- 
sisted of granites and gneisses of typical Laurentian aspect. 
For forty miles north of Cape Esquimaux no rock in place was 
seen, and thence northward to Baird bay some of the points con- 
sisted of granite and gneiss, though the shore generally consisted 
of Huronian rocks.' 
' The largest area of Huronian rocks found in this district 
extends more or less continuously for 120 miles along the west 
coast of Hudson bay, from near Baker's foreland to a point 45 
miles north of Cape Esquimaux.' 
' The rocks constituting this system may be divided into three 
more or less distinct groups, viz. : The Marble island quartzites, 
the greenish quartzites and graywackes, and the more or less 
highly altered, and often schistose diabases and gabbros.' 
' The Marble island quartzites are composed of hard white 
quartzite, consisting of more or less rounded grains of quartz, 
