16 COAL RESOURCES OF THE YUKON. [no 218. 
and in some instances having very intricate stratigraphic relations. 
This succession contains some horizons which have been fairly well 
established by stratigraphic and paleontologic studies, but also o J ' rs 
whose position in the geologic column is very much in doubt. 
An examination of the table will show that the oldest rocks in the 
region are of a gneissoid character, and for these the name Peily 
gneisses has been suggested by Brooks and accepted by McCon- 
nell. These Pelly gneisses are an intricate series of crystalline 
rocks whose genesis is doubtful. A part of the rocks grouped with 
these gneisses are altered intrusives, and closer investigation will 
undoubtedly show that some of them are younger than the sediments 
they are supposed to underlie. One belt of the Pelly gneisses occurs 
in the Fortymile, along the axis of an anticlinal uplift, as described 
by Spurr, and another was seen by the writer between the Melozi a and 
the Yukon. The gneissic series everywhere shows evidence of having 
been subjected to profound metamorphism. The Pelly gneisses are 
succeeded unconformably by a great thickness of quartz-schists and 
quartzites, called by Spurr the Birch Creek series. These pass above 
into a white crystalline limestone formation named the Fortymile 
series by Spurr. Both of these series find extensive development in 
the upper part of the region under discussion. The Rampart series, 
characterized by rocks of greenish color and preponderance of volcanic 
matarial, overlies these unconformably, and is probably of Devonian 
age. The two older formations are more altered than the younger, 
but all have undergone considerable deformation and igneous intru- 
sions are abundant. 
Near Seventymile River the writer found a series of black slates 
and shales interbedded with thin bands of semicry stall ine limestones, 
in which Lower Carboniferous fossils were found. These beds are 
intensely crumpled. 
The next succeeding horizon is the so-called Tahkandit .series o 
Spurr, which is made up of conglomerates, sandstones, and shales 
overlain by a heavy bed of semicrystalline limestones, which has 
yielded abundant fossils near Nation River. These fossils are 
regarded as Permian. Spurr 's Tahkandit group is not included in 
the accompanying table, because he gave to this name a broader 
significance than can be accepted in the present investigation. This 
sandstone, conglomerate, and limestone series is closely folded and 
much metamorphosed. 
Below Nation River the Permian beds are overlain b}^ a great thick- 
ness of black, slaty shale containing some intercalated beds of lime- 
stones and calcareous sandstones. In these beds the writer found 
fossils which were determined by Dr. Stanton to be Aucellae of Lower 
a This river is known in Alaska as the Melozikakat. Melozi is here used in conformity with the 
decision of U. S. Board on Geographic Names, "kakat"' being merely a native term for river 
; 
