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the Yukon silts, which have not been touched upon in this description. There was a time, too, when volcanic dust from some distant source to the southward was deposited in a thin layer over large areas of the Fortymile region, where it occurs just beneath the surface as a deposit similar in appearance to quicklime.
The following report was prepared by Doctor Knowlton on the material collected from the various localities visited by the party:
Fossil plants obtained by L. M. Prindle from various localities (luring the
season of 1903. [By F. H. Knowlton.] SAP 224. Irene Gulch. Chicken Creek: Fragments of stems, indeterminable. SAP 224J. McDowell claim. Chicken Creek: Equisetum sp. SAP 237. Mouth of creek. 1 mile' west of Chicken: Black carbonaceous shale
with minute plant fragments. indeterminable. :'.AP 251. Chicken Creek: Fragments of dicotyledons, possibly Corylus Mae
Quarril. but uncertain. .".AP 330. Wolf Creek: Taxodium (labium? ITeer: Populus sp. 3AP 330. Branch of Wolf Creek: Populus. cf. P. Richardson) Ileer: dicotyledonous fragments. 3AP 337. Branch of Wolf Creek: Only fragments of stems and bark. 3AP 34S. Bryant Creek: Sequoia Langsdorhi (Brgt.) Ileer; Taxodium dubium? Ileer; Populus arctica? Ileer; Populus Richardson!? Ileer; Corylus MacQuaiTit (Forbes) Ileer; Quercus platania Ileer; Betula prisca? Ett. 3AP 349. Bryant Creek: Sequoia Langsdorfli (Brgt.) Ileer; Corylus MacQuarrii (Forties) Heer; Populus arctica Ileer: Populus Richardson!? Ileer; Juglans nigella? Heer. SAP 350. Bryant Creek: Sequoia Langsdorfli (Brgt.) Heer; Equisetum sp.; Populus Iatior Heer: Populus Hookeri Ileer; Fagus Deucalionls linger: Quercus furcinervis (Ross M.) linger; Juglans sp.? 3AP 355. Mogul Creek: Sequoia hrevifolia? Heer; Corylus MacQuarrii
(Forbes) Ileer; Populus sp.? SAP 432. Mission Creek, 2 miles above junction with Excelsior: Corylus MacQuarrii (Forties) Ileer; Betula prisca Ett.; Fagus Deucallonis linger. Listing the species from all the localities, we have the following: Full list of species collected. Sequoia Langsdorfli. Corylus MacQuarrii.
Sequoia hrevifolia. Quercus furcinervis.
Taxodium dubium. Quercus platania.
Populus arctica. Fagus Deucallonis.
Populus Iatior. Betula prisca.
Populus Richardson!. Juglans nigella.
Populus Hookeri. Taking well into account the fact that not all of the above species are determined with absolute certainty, it is nevertheless perfectly clear that all are of the same age. and I do not hesitate to say that this is Arctic Miocene." Not a trace of the Cretaceous element appears.
"This flora was (Irst descrlbed Hs the Arctic Miocene. Subsequent investigations un shown tuut It Is of Eocene age, but the old nume Is still retained.—L,. M. Prindle.
pMNDLe.] FORTYMILE, BIRCH CKEEK, AND FAIRBANKS PLACERS. 39
Since the discovery of gold on Fortymile Creek, in 1886, prospectors have devoted much attention to its basin. The most important creeks at present are Wade, Walker Fork, Chicken, and Franklin, while some work is being done on the Fortymile itself, Napoleon Creek, the tributaries of Canyon Creek, and on North Fork of Fortymile. Prospecting is in progress in many places and still results occasionally in discoveries of economic importance.
Wade Creel-.—The basin of Wade Creek, which is reached by trail from the mouth of Steele Creek, lies about 10 miles south of the Fortymile, and embraces about 50 square miles (map, Pl. VII). The creek, which is about 12 miles long, heads in Steele Dome, 3,750 feet high, and flows in a nearly straight southwesterly direction, entering Walker Fork a few miles above its mouth. There is a fall of about 000 feet from the upper limit of placer mining to the mouth—a distance of about 8 miles. The valley is sunk to a depth of about 1.500 feet within the plateau, and is narrow and V -shaped in its upper portion-; lower down it gradually widens, finally merging into the valley of Walker Fork, where the stream follows a meandering course over the surface of a broad flat. The spurs from the northwest descend somewhat more gradually toward the stream than those from the opposite side, and the cross section-of the valley is thus somewhat unsymmetrical. The general characteristics are shown in Pl. VI, B. The tributaries are short and flow in narrow V-shaped valleys. In dry seasons the demand for water far exceeds the supply, and much of the mining is brought to a standstill.
There is considerable timber on the northwest slopes of the valley, and a light growth of spruce on the southeast. The valley floor is generally covered with willows, but in the wider portion, toward Walker Fork, is well timbered with spruce and aspen. Dawson is the main source of supply, and most of the freighting is done during the winter.
The bed rock in which the valley of Wade Creek has been incised includes several varieties of schist and some ferruginous, thinbedded limestone, which is apparently interbedded with the schist. Mica-schist and hornblende-schist are the most common rocks. Their attitude is variable, but the general strike is northeast, about parallel with the creek, and the dip of the schistosity varies from nearly horizontal to 50c or more to the southeast, while a prominent system of joints strikes N. 30° W. The schists are often contorted and the structure is probably complex. A small dike of basalt, with a strike of N. 00° E., was observed about a mile above Robinson Creek. Quartz veins are common in the schist and seem more abundant toward the head of the creek. Both bed rock and quartz veins contain in places considerable pyrite.
The gravels vary from 1 foot to 3 or more feet in thickness and are composed of the rocks that are found outcropping in the valley and along its slopes, no foreign material being observed. The proportion of vein quartz is small. The fragments are more or less angular, owing to the schistose and jointed structure of the bed rock, are little worn, and are generally less than a foot in diameter. They are found across the entire width of the valley and on the low bench-like termination of the spurs, perhaps 10 to 20 feet above the valley floor. The gravels are covered with a layer of muck up to 20 feet in thickness.
It is said that gold was discovered on this creek by Jack Wade about 1895. Rim prospects were found in the fall of 1898. The gold is rarely found more than l| feet above the bed rock in the gravels. Most of it is on bed rock and extends into it in crevices and along joint planes to a depth, in places, of 4 feet. It occurs rather irregularly, and the creek has the reputation of being spotted. Good pay was first struck on the rim at the terminations of the spurs on either side, and these became the favorite localities for work. The pay there is more accessible and found frequently in greater quantities than on the valley floor.
As much of the gold occurs as nuggets, which are irregularly distributed, it is difficult to form an idea of the average value of the ground. It is said to average about $100 to the box length of 12 by 12 feet, but some ground has yielded, by the winter's work, from 50 cents to $3 per cubic yard, including everything from surface to bed rock.
Much of the gold is picked up during the work, and many nuggets have been found. One was found during the winter of 1900 worth $216; and in January, 1903, one was picked up which measured H by lj by 1J inches and was worth $558. A week later another was found worth $437.85 in gold, valued at $17 to the ounce. The nuggets are well smoothed, of a bright yellow color, contain very little quartz, and are often convex on one side and more or less flat and irregular on the other. Some of the prospectors had observed that the nuggets found by them were generally rougher on the side lying next to bed rock. The larger nuggets have been found in the part of the valley which is about midway between the source and the mouth. . The gold occurs generally as small flat pieces, and a large portion of that from the head of the creek is rusty. The little gold found in prospecting the side gulches differs in character from that in the main creek in that it is very rough and somewhat rusty. Very little fine gold is found, and the proportion of black