32 GRAVEL AND PLACER MINING IN ALASKA. [bull. 263. 
accounted for by the fact that the second denudation has progressed 
for a great period, and the comparatively small amount or vertical 
section of gravel which existed subsequent to the elevation has been 
worn away. 
In the Klondike recent streams have cut the old Pleistocene chan- 
nels and have reconcentrated the gold. a The gold is about equally 
distributed in the old and in the new gravels. From the miner's 
standpoint, therefore, in the Klondike region there are two great 
classes of mining to be considered, namely, creek mining and bench 
mining. Outside of these two classes there is no mining in the Klon- 
dike of productive importance. 
In the Birch Creek district, especially on Deadwood Creek, there is 
a very small amount of gravel in low benches which may be termed 
hillside deposits. The bulk of the mining, perhaps 90 per cent of it, 
is creek mining in its various forms. The terms bench deposit, hill- 
side deposit, and the like are very loosely applied by the miners of the 
Northwest, and names are given to classes of mining to which they 
do not in any sense apply. This looseness of nomenclature is apparent 
in the Fairbanks district, where the term bench mining is applied on. 
Cleary Creek to operations in progress on the left bank of the stream 
at a place one-fourth mile above the junction of Cleary and Chatham 
creeks. But whereas the depth to bed rock in the main creek at this 
point is 18 feet, the depth on the so-called bench, 700 feet to the left, 
is 53 feet, and the level of the bed rock at which the gravel is found 
is practically the same. In the one case, namely, in the creek work- 
ing, the overburden is 6 feet of muck, while in the "bench" to the 
left the overburden is over 45 feet of muck. The gently sloping side 
of the valley at this point is unbroken in outline. 
Observations along the various producing creeks and from the 
hilltops have failed to distinguish any traces of bench topography 
in the Fairbanks district. Such placer mining as is carried on there 
comes under the head of creek mining. Geological evidence, how- 
ever, suggests that bench deposits occur in the region lying between 
the Fairbanks and Rampart districts. 
The methods applicable to bench mining at Dawson can not be 
used in the Fairbanks district, and all thought of applying them must 
be eliminated. The country being in every sense of more gentle 
topography, there is no room for the disposal of tailings from bench 
operations conducted by hydraulicking. 
On Pedro and Twin creeks there are about 2 miles of ground less ! 
than 15 feet in depth which can be worked by open cutting, either by 
shoveling into sluice boxes or by derricking. On a portion of this 
ground it is possible to handle the water by bed-rock drain. Open 
cut mining has also been successful on Chatham Creek near its June 
a See McConnell, R. G., Preliminary report on the Klondike gold fields: Geol. Survey Canada, 1900. a 
