ALASKA. 45 
where the gold was found to originate in veins and mineralized zones 
in the older schistose formations. From these sources it had been 
washed out and concentrated in the placers. 
In the reconnaissance trips of 1898 the distribution of gold was 
determined in many areas. The rocks of the Sushitna Valley were 
briefly described, and the origin of the placer gold was referred to the 
quartz seams in the Sushitna slates. In a trip across the Alaskan 
Range the mineralization was found to be much less than in the mining 
regions of the Yukon. It seems to be limited to a portion of the 
range and to be dependent on the intrusion of igneous rocks. The 
schist formations of the Tanana country were found to be similar to, 
and probably to belong to, the same horizon as the gold-bearing rocks 
of the upper Yukon. The regions which might prove of economic 
value for their mineral deposits were outlined, and it is interesting to 
note in this connection that the new mining camp of Fairbanks has 
recently been developed in one of these areas. Along the southern 
coast the gold deposits of the Sunrise and Matanuska regions were 
investigated, the process of natural concentration of gold -in placers 
was described, and the possibility of hydraulic and quartz mining was 
considered in the published reports. In the Copper River country 
gold was found to occur in small amounts in quartz stringers, and 
these were considered the source of the placer gold which was found 
in limited quantities. 
In 1899 the Porcupine placer district was examined and the gold was 
found to be derived from mineralized areas in the slate. In the same 
year the gold deposits of the Koyukuk were described. At the end of 
the season the newly discovered gold deposits of Nome were investi- 
gated. This work resulted in the first accurate report of the region, 
which was ready for the public the following spring. The topog- 
raphy, country rock, and gravels were described. The fact was em- 
phasized that the source of the gold was in the hills, and not, as many 
supposed at that time, offshore. The attention of prospectors was 
directed to the high gravels occurring as terraces on the hill slopes, and 
these have since been worked with very profitable results. It was 
further predicted that the tundra between Nome and the hills would 
probably produce gold in paying quantities, as it is now doing. The 
manner in which concentration has been brought about by wave 
action was described, and the methods of mining employed at that 
time were reported. The work of these few weeks may be taken as 
an illustration of the practical value of the Survey's investigation. 
Work was continued in Seward Peninsula the two following years, 
and again in 1903, and data were collected on the occurrence and distri- 
bution of the gold. The facts were established that the gold was con- 
centrated in the placers from a comparatively local origin in the 
schists, and that the richer occurrences frequently had their origin in 
