WRIGHT.] 
ECONOMIC GEOLOGY. 
21 
attempting to determine the 
show the possibility of any 
outside origin, because the 
deposits are so limited in 
extent. If the gravels, with 
their gold contents, had been 
brought into these creeks by 
glaciers, there would be no 
reason for the observed con- 
centration in one stream and 
the absence of gold in adja- 
cent gulches. This and the 
fact that pay gravels are not 
found in the upper portions 
of the gold-bearing creeks 
above the mineralized slates, 
nor in the diorite belt, 
strongly suggests that the 
gold has been derived from 
the surrounding country 
rock. 
The problem is quite simi- 
lar to that presented by the 
auriferous gravels of the 
interior and of Seward Pen- 
insula, where the local source 
of the gold concentrated in 
the placers is usually ac- 
cepted. 
Natural washing and re- 
concentration of the aurifer- 
ous bench deposits by small 
tributary streams has con- 
tributed a large amount of 
gold to the gulch gravels. 
This explains the occurrence 
of rich deposits in potholes 
and the irregular distribu- 
tion of gold 
beds. 
or 
igin of the gold, but it is difficult to 
n the gravel 
1 )EVELOPMENTS. 
After the rush to Porcu- 
pine Creek in 1898-99 but 
little development was undertaken until 1900, when several claim 
Fig. 1. — Map of Porcupine Creek, showing location of 
claims. 
