LINDGKEN.] 



GRAVELS OF UPPER MOORE CREEK VALLEY. 



661 



City, a series of shelf-like terraces, entirely absent farther down, 

 begin to appear. The width is only a few hundred feet, and rarely 

 are longer stretches of them preserved, each little creek and gully 

 usually cutting the terrace in two. For the first 4 miles most of the 

 gravel patches lie on the northern side of the valley. At least twp 

 terraces may here be recognized, the bed rock of the lower one being 

 50 and of the upper about 10O feet above the creek. The depth of 

 the gravel is seldom over 30 feet, though near the bed-rock slopes 

 much debris has slid down over the gravel. All of these gravel 

 patches have been very rich, and work is still in progress on some of 

 them. The bed rock, as far up as 1 mile below Warm Springs, is 

 granite or granite-porphyry. 



Above Warm Springs the gravel terraces or benches are very pro- 

 nounced and often form continuous streaks of considerable length. 

 The best exposures are found at Turner's claim, 1 mile below Idaho 

 City, on the road to Warm Springs. At this place the gravel ter- 

 races occupy a total width of one-half mile, and rest partly on gran- 



Moore Creek 

 TatfJngs 



Horizontal Sc&te. 



IOOO 



Feel- 



Vei-rlcal Scale. 



) IOO ZOO 300 



feel- 



FIG. 55. Gravel benches 1} miles below Idaho City. 



ite, partly on Tertiary lake beds, gently inclined westward. Fig. 55 

 shows a profile of the different terraces here exposed. The highest 

 terrace is found at an elevation of 80 feet above the creek bed. 

 Below this there are three others, and possibly four, at intervals of 

 15 and 30 feet. The lowest terrace is said to be covered by the tail- 

 ings. These gravels have been very extensively washed, but a con- 

 siderable amount still remains. The upper terrace, illustrated in 

 fig. 56, is covered by 8 to 12 feet of well-washed gravel, chiefly gra- 

 nitic in character. This contains the largest part of the gold, and 

 rests on the eroded surface of the soft lake beds. This pay gravel 

 is again covered by 12 feet of fine sandy or clayey sediments with 

 occasional carbonaceous seams. In this there is but little gold. On 

 top rests 8 feet of angular surface gravel, washed down from the 

 adjoining hillside. This gravel is barren. The gravel terrace extends 

 in a northeasterly direction along Elk Creek, and is chiefly developed 

 on the western side. The continuous bodies give way to isolated 

 patches, and 2 miles above Idaho City Elk Creek passes into a nar- 

 row canyon. In Idaho City gravel terraces are noted surrounding a 



