NOME REGION. 129 
separated from the underlying Kigluaik series, and in fact exactly 
similar beds are found interstratified with the biotite schists of that 
series. A doubt therefore arises as to whether these two should be 
separated. 
NOME SERIES. 
South of the Salmon Lake and Sinuk River valleys and extending 
to the coast of Bering Sea is a region of schist and limestone intruded 
by greenstone, and in the vicinity of Cape Nome by granite, to all of 
which the name Nome series was given. In general the strata dip 
to the north in the portion of the region south of the latitude of Mount 
Distill and to the south in the portion north of that latitude, thus 
forming a broad synclinal trough on whose axis Mount Distin is 
situated. The rocks forming this trough are chiefly schists, with 
limestone in lesser amount. The greenstones cut both of these in the 
form of sills and dikes. All have been highly metamorphosed. The 
limestones, which are found most abundantly in the upper part of 
the Nome series, have been entirely recrystallized and any organic 
remains they may have contained are now seemingly obliterated. 
The original argillaceous sediments, more highly developed in the 
lower portion of the series, and the greenstones intruded in them are 
also recrystallized and possess a well-developed schistose structure. 
The schists may be described freely as micaceous, feldspathic, or 
graphitic in character according as the minerals mica, feldspar, or 
graphite are prominent. The micaceous schists, in places highly 
siliceous, are usually green or silvery gray in color; the feldspathic 
schist is green, though this color is partly hidden by the development 
of numerous small feldspar crystals; the graphitic schists are black, 
becoming gray as the amount of carbonaceous matter decreases and 
quartz becomes more evident. The feldspathic schists are in many 
places conspicuous by reason of the abundance of small albite crystals, 
which are especially noticeable on the weathered surface. They are 
derived in part from original sediments, but probably in the main 
from intruded greenstones. 
Greenstones are more common as sills than as dikes and are usually 
highly altered. In general their conspicuous minerals are chlorite 
and albite, but in some localities they are filled with red garnets. Like 
the feldspathic schists, into which they grade locally, they are more 
abundant on the east side of Nome River than on the west and are 
perhaps most highly developed in the area between Osborn Creek and 
Nome River. 
Only one notable area of granite is found within the Nome series 
in the region under consideration. It is seen in the two ridges run- 
ning northward and northwestward from Cape Nome. This granite, 
Bull, 314— 07 9 
