662 



IDAHO MINING DISTK1CTS. 



high body of older gravel called East Hill. A part of this terrace, 

 on which the town stands, has not yet been mined. Opposite Idaho 

 City, and in fact all along the southern side of Moore Creek up to 

 the mouth of Granite Creek, the gravel benches are more or less con- 

 tinuous. The lowest is noted 20 feet above the creek and higher 

 ones are at 50 and 100 feet. Small benches occur on the north side 

 of Moore Creek east of Idaho City. At least three different benches 

 may be recognized at the elevations noted. Most of these bench 

 gravels near Idaho City rest on lake beds of sandy or gravelly char- 

 acter, usually referred to by the miners as ' ' false bed rock. " 



All the small patches of gravel terraces have been extensively 

 washed and are not yet quite exhausted. The thickness of the gravel 

 rarely exceeds 25 feet. 



Above the mouth of Granite Creek, Moore Creek enters a canyon, 

 along which there are but small indications of gravel terraces. At 

 Plowman's sawmill the creek widens somewhat, and from here up 

 the bottom is generally occu- 

 pied by a flat 100 to 300 feet 

 wide, the surface of which is 

 10 to 20 feet above the creek. 

 Upon the sides are occasional 

 benches at an approximate 

 height of 50 feet above the 

 creek. All these low terraces 

 have been washed as high up 

 as the mouth of Gambrinus 

 Gulch, and from the evidence 

 of the old washings it is clear . 



FIG. 56. Section of highest bench, 1J miles below 



that most of the gold came Idaho city. 



down from this gulch. Above 



Gambrinus Gulch the washings are less extensive, and some of the 

 low gravel flats have never been worked, being evidently too poor. 

 Two miles above Idaho City, as stated above, Elk Creek enters a nar- 

 row canyon, and although this widens somewhat farther up, still 

 there are only occasional patches of gravel terraces remaining, at 

 elevations of about 50 feet above the creek. The manner of mining 

 the bench gravels by the hydraulic process is shown on PI. XCIV. 



High gravels. There are several bodies of gravel in the vicinity of 

 Idaho City which in their occurrence differ from the ordinary bench 

 gravels, and which are generally at high elevations above the creeks. 

 While these also are probably former terraces of the valley of Moore 

 Creek, they are much older, and it seems desirable to treat them 

 separately. 



The slope opposite Idaho City is occupied up to 400 feet above the 

 creek by soft lake beds cut up into sharp ridges separated by deep 

 and narrow ravines. The gently sloping tops of these ridges are 



8 r&eh Angular 

 Surface Gravel. 



