358 REVIEWS 



The preliminary determination of the geologic series of the Atlin 

 district is as follows : 



i. Sandstones and argillites of probable Cretaceous age, in the basins of 

 southern Taku arm and Atlin Lake, with an expected continuation to the south- 

 east by Pike Lake, and the Nakina River. 



2. The characteristic rocks of Pine Creek basin are different varieties of 

 magnesian combinations, together with some greenstones of a diabasic 

 character. Magnesite, serpentine, dunite, greenstone, actinolite slates and a 

 very friable gray limestone are the chief rocks. These were not seen outside 

 of the Pine Creek and McKee Creek basins excepting in two or three locali- 

 ties. They extend in patches across Atlin Lake westward into Taku inlet 

 and possibly over towards Taku arm to a point five miles south of Toochi 

 River. Another area of these typical rocks is found about Chehalis Creek, 

 south of Gladys Lake, as mentioned previously. 



3. Cherty quartzites and various kinds of clay-slates, together with patches 

 of gray or black limestone distributed over the great flats west of Dawson 

 Peaks and Gladys Lake, O'Donnel River basin, and eastwards to Teslin 

 Lake at its southern end. 



4. Great masses of crystalline limestones on northern Taku arm, Little 

 Atlin Lake, Lower O'Donnel River, and at the junction of Silver Salmon and 

 Nakina Rivers. 



5. Late eruptive rocks of basaltic and porphyritic characters, all about 

 the southern parts of Atlin Lake, constituting the central portions of most of 

 the groups of mountains there. 



6. Granites of the Coast Range at the south end of Taku arm, and isolated 

 masses of granite from the northern end of Atlin Lake eastwards across 

 Surprise Lake, and Snowdon Mountains to near Teslin Lake ; also McMaster 

 Mountains east of Lower O'Donnel River, and the bowlder-stream plateaus 

 seventeen miles eastward, from Ruth Lake on the Taku trail. 



The conclusions relating to the ages of the rocks in the Kootenay 

 district are as follows : 



The crystalline gneisses and schists are of uncertain age, probably they 

 include rocks of different age, but they are, at all events, among the oldest 

 rocks of the district. The Nisconlith rocks are Lower Paleozoic, supposed 

 to be about Cambrian. The Cache Creek rocks are Upper Paleozoic, probably 

 Carboniferous. This is the age also assigned to most of the greenstones 

 (andesites, porphyrites, serpentines, etc.), and the limestones and argilites 

 associated with them. Some of the andesite and agglomeratic rocks in the 

 Trail Creek district are no doubt younger, but there is no definite information 

 regarding their age except that they are older than the conglomerates and 

 the Rossland granite. The gray granite which cuts the greenstones is probably 



