120 ALASKAN MINERAL RESOURCES IN 1905. 
Esther Creek is only about 5 miles long and flows in a nearly straight easterly course. 
The upper part of the valley is narrow; the lower part is open, shallow, and flat. A well- 
defined bench composed, so far as known, of fine sediment occurs on both sides of the upper 
part of the valley about 40 feet above the floor and appears to be recognizable in the lower 
part of the valley through the presence of remnants. The deposits are similar to those 
described, ranging from 25 to 90 feet and in one case to 135 feet in depth. A section of these 
last deposits from surface to bed rock is reported to be composed of 30 feet of muck, 80 feet 
of gravel, 14 feet of muck, 4 feet of clay containing some gold, and about 6 feet of barren 
gravel. An ancient beaver dam was found at a depth of 25 feet beneath the surface. On 
the next claim below this section the bed rock was found at a depth of only 90 feet. The 
cause of the difference in depth of the underlying surface is probably to be found in the dif- 
ference of drainage conditions at the time the material was deposited. The search for gold 
on this creek should be guided qo1 so much by the course of the present stream as by the posi- 
tion of known occurrences of gold, nor should it be assumed that the pay streak necessarily 
follows a line connecting two or more occurrences. 
The creek is small, furnishing in the upper part of the productive area during the time of 
least rainfall less than half a sluice head of water, the grade of the valley is low, and the 
deposits are deep. Some excavations have been made at points scattered along about 3J 
miles of the valley and, although these are insufficient to determine the continuity or average 
dimensions of the pay streak or its position in the valley, enough gold has been extracted to 
justify thorough exploitation and to establish the creek as a good producer. 
MINING METHODS. 
The methods of mining in the Fairbanks region are the same as those used extensively for 
similar types of deposits in the Klondike region already described in detail by Purington.a 
Therefore only those points will here be set forth that illustrate most clearly the line of prog- 
ress dining the season of 1905. The methods have been necessarily determined by the 
grade of the valleys, t lie thickness and character of the deposits, and the available water 
supply. Only a small part of the ground has a grade of over 100 feet to the mile and most of 
it is considerably less. The deposits worked vary from a few feet to over 120 feet in thick- 
ness. The creeks are small, carrying ordinarily 200 to 400 miner's inches of water, although 
during the past season the abundant rainfall furnished enough water for all methods of 
mining. In dry seasons the present sources of water supply would be inadequate and, 
while thus far only short ditches have been in use, a project is under way to supply Cleary 
Creek with water from the upper part of the Chatanika Valley by means of a ditch about 35 
miles long. 
PROSPECTING. 
As it is an almost universal experience that the pay streak, if present, lies on bed rock, the 
chief work of prospecting consists in sinking holes to bed rock. Thawing the ground is usu- 
ally necessary and, while the crude methods requiring wood fires, hot rocks, or hot water are 
still in use, the most approved met hod and the one most commonly employed is that carried 
on by means of steam, as described below 7 . Small, portable, knockdown steam thawing out- 
fits that can be packed on horses are now obtainable, thus permitting prospecting in remote 
areas. After the ice has been melted the material to be excavated is loosened with a pick, 
shoveled into a bucket, and hoisted to the surface, usually by hand windlasses. If the 
ground is deep the prospect shaft is generally timbered to the depth of the overlying muck. 
The most formidable difficulty encountered in sinking is live water, which often necessitates 
the abandonment of shafts. Great depth of ground also increases the difficulty of sinking 
holes and consequently makes the work of locating the pay streak slow. The method of 
prospecting by drilling has not been introduced in the Fairbanks region, but would probably 
find a place. 
" Purington, C. W., Methods and costs of gravel and placer mining in Alaska: Bull. U. S. Geol. Survey 
No. 263, 1905. 
