128 ALASKAN MINERAL RESOURCES IN 1906. 
It is the purpose of this paper to give a preliminary statement o 
the more important facts gathered during 1905 and 1906 bearing oi 
the geology and the source and distribution of placer gold in the 
portion of Seward Peninsula represented by the two topographic 
sheets known as the Nome and Grand Central special maps. Th( 
paper is not complete, since it goes to press too early to permit 
thorough study of the data collected. The final conclusions, togethei 
with the two maps mentioned, will be published in a forthcoming 
bulletin of the Survey. 
GENERAL GEOLOGY. 
The important features of the bed-rock geology of the region wer 
recognized and correctly interpreted by Brooks and Collier. As stated 
by them, the rocks are chiefly sedimentary, limestones and schists, 
but in many places have been intruded in an intricate manner by 
igneous rocks of several kinds, more especially by greenstones aifl 
granite or rocks of a granitic character. Brooks referred the sedi- 
ments to three periods of time and described them under the names 
of Kigluaik, Kuzitrin, and Nome series/' A brief account of these 
will be given. 
KIGLUAIK SERIES. 
The oldest known sedimentaries of this region are exposed in thl 
Kigluaik or Sawtooth Mountains and are well represented in Mounfr 
Osborn, a short distance north of the northern limit of the are* 
shown on the Grand Central map. The relative age of the beds is 
known only by their stratigraphic position, for no fossil remains have 
yet been found in any of the rocks to be described. 
They comprise biotite and graphitic schists and limestones, togeth< 
with gneisses and granite or related intrusives. In Mount Osboi 
the schist and limestone beds lie in a nearly horizontal position, but 
on the southern side of the Kigluaik Range they dip rather gently to 
the south and beneath the younger sedimentaries. This succession 
of beds was given the name of Kigluaik series. 
KUZITRIN SERIES. 
A highly irregular series of beds consisting of siliceous graphitic 
schists occurring along the south flank and east end of the Kigluail 
Range was called by Brooks the Kuzitrin series. It has a reguh 
southerly dip and is not found south of the Salmon Lake valley, bul 
is possibly represented by beds occurring on Charley Creek south 
Sinuk River. No conclusive evidence was found within the Gran< 
Central area, however, showing that these black schist? should 
a See p. 83 (footnote b) in regard to use of the term " serie;," 
