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University of California . 



[vol. 3. 



in extent, but the original surface seems nowhere preserved. 



The outer and lower channel of the Pearch Mine has been 

 pretty thoroughly cleaned out, and displays a trough 200 to 

 300 feet wide, which is separated from the river by a distinct 

 rim or rock ridge about twenty feet high. The floor of the 

 channel is at present about thirty-five feet above the river and 

 the crest of the rim about fifty-five feet. The gravel in the 

 channel appears to have been moderately coarse, but boulders 

 over two feet in diameter are rare. Over the outer rim there 

 are a few remnants of the terrace deposit. At the base there 

 is a thin layer of gravel, over this a ten foot stratum of brown 

 sand and above this a five foot stratum of brown sandy clay 

 abounding in small, waterworn slate fragments. There are a 

 few small remnants of the original surface at a level sixty-five 

 or seventy feet above the river. There can be little question that 

 this is a remnant of the seventy-foot terrace. 



There is a fragment left of the original surface over the 

 inner rim, but it is fifteen or twenty feet higher than the terrace 

 level on the outer rim. Over the bed-rock there is. thin gravel, 

 then brown sand, followed by a fine pebbly layer as in the 

 outer edge of the deposit. It appears that the terrace had a 

 distinct slope toward the river. But a remnant of the 120-foot 

 terrace so abruptly overlooks these lower terrace remnants as 

 to make it evident that one did not merge into the other, but 

 they preserved their individuality here as elsewhere. 



Immediately above Orleans, on a long point that projects 

 out into the valley, there is an old mine, commonly known as 

 the "Wilder Diggings." It exposes two channels which have 

 courses nearly at right angles to the present river. The higher 

 has been worked off to the extent of about 700 x 400 feet. There 

 is a broad, comparatively even rock platform at sixty-five feet 

 above the river, and back of this there are traces of a slightly 

 lower channel surface. The original deposit is exposed around 

 two-thirds of the circumference of the mine, and presents some 

 significant features. Over the bed-rock there is a moderately 

 coarse gravel bed with lenses of false-bedded sand and fine 

 gravel, these lenses usually having a decided dip. The thickness 

 of the gravel is from ten to twenty feet. It is overlaid on all 



