Wednesday, August 24, 2011

Challenging Spots for Gold Panning - "Cherry Creek"

From the Colorado Geological Survey, Department of Natural Resources, Denver, CO 2009

Challenging Spots for Gold Prospecting and Panning in Colorado

The Cherry Creek Divide Area
Araphahoe, Denver, Douglas and Elbert Counti

This area boasts the locations of the significant gold strikes of 1858 by William Greeneberry Russell and his party, which led to the "Pikes Peak or Bust" gold rush of the following year.

The first worthwhile goldstrike was on the South Platte River, in Denver County, near Overland Park between 8th Ave and Jewell. The most productive deposits found were on Big Dry Creek, Newlin and Russellville Gulches in the Cherry Creek drainage in Douglas County and on Ronk (now called Gold Creek) and Gold Run gulches to the east of Russellville gulch in Elbert County.

These placers were abandoned by the end of 1859, as the miners left for the richer goldstrikes at higher elevations such as Idaho Springs, Central City and elsewhere that same year.

However there has been both gulch and drift mining in the Cherry Creek drainage from time to time since, especially individual and small-scale operations during the depression and at other times as well.

The gulches in which the placers lie drain the Cherry Creek Divide, which is capped by the Oligocene Castle Rock conglomerate. This formation forms "Castle Rock" overlooking the town of the same name. To the NE of Castle Rock town the conglomerate has been eroded by streams and now is represented only by remnants capping buttes along the divide. Many hillslopes have residual pebbles and cobbles on them derived from the erosion of the conglomerate.

These are terraces or benches at many places along the streams. Along the S Platte the terraces are 40 feet above the level of the river. These benches extend into Cherry Creek and its tributaries, their height diminishing upstream.

Gold has been found in the terraces and in the stream beds. Testing has shown that gold in the bench placers lies on or near bedrock but gold in the stream beds is nearer the surface.

The Castle Rock conglomerate contains gold at numerous locations in this area.

In upper Newlin gulch near the forks, the lens shaped beds of gravel were found to contain up to one ounce of gold per ton in individual samples. These lens shaped deposits were 5-40 feet above modern stream levels, near the base of the Castle Rock formation itself.

The gold in the Castle Rock formation/Cherry Creek drainage placers was typically fine-grained - 10 to 50 colors per milligram. Miners described it as almost flour gold and complained of the difficulty of its recovery from the clayey gravel matrix. Even so, colors up to one-sixteenth inch diameter were found. The Castle Rock formation gold is among the purest placer gold on earth, characteristically about .990 fine!

The source of the stream and terrace placer gold is the Castle Rock conglomerate and fossil stream placers in it. That the source is fossil stream channels explains the erratic distribution of gold among the gulches and also the erratic distribution within each of the gulches.

Access is difficult because of the extensive development in the area. There is little water and the gravels must be packed out.

Remember to always get permission before entering any property, backfill all holes and leave your site cleaner than you found it.

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