ILLUSTRATIONS. 
Pase. 
Plate I. Outline map of Alaska ( .) 
II. A, Steele Creek with Fortymile Creek in the foreground; B, 
(J lacier .Mountain 10 
III. A, Canyon of Fortymile. 500 feet below the level of the old 
valley ; B, Surface of bench, r>00 feet above level of Sev- 
entymile 20 
IV. Geologic map of tbe Yukon-Tanana area 22 
V. .4. Schists on South Fork of Birch ('reek; H, Contorted 
schist on ridge north of Mosquito Fork '_ 28 
VI. ,4. Schists with thin granitic sill on trail from Wade Creek 
to Walker Fork; B, Looking up Wade Creek 30 
VII. Map of Fortymile quadrangle 34 
VIII. A, Washing the overburden from the gold-bearing gravels. 
Wade Creek ; H, Steam scraper with bucket conveyor at 
mouth of Poker ('reek 38 
IX. .4, Shaft and horse hoist on Chicken Creek; B. Dump of pay 
dirt on Lost Chicken '_ 48 
X. .4. Artificial cut-off in schist on North Fork of Fortymile; li. 
Bed of the North Fork drained by artificial cut-off __ 50 
XI. Hydraulic plant on American Creek 54 
XII. A, Looking up American Creek: B, Bridge for conveying 
water in a canvas hose across Seventyinile 50 
XIII. Reconnaissance map of Fairbanks and Birch Creek districts- 60 
XIV. A, Steam shovel operating on Mammoth ('reek; B, Bed of 
Mastodon Creek worked by open cuts 02 
XV. A, Sluicing on Pedro Creek ; B, Thawing apparatus on 
Cleary Creek 70 
XVI. Reconnaissance map of Yukon-Tanana region In pocket. 
