Dames & Moore, 1999 - USDA Forest Service

appears to be relatively localized. No mineral claims and/or mapped deposits were noted in the immediate
area and/or hydrologically upgradient of the Bridge Creek sampling location (BC- 1) (Church et al., 1984).
Two relatively small mines were located apparently upgradient of the South Fork of Agnes Creek sampling
location (SFAC- I). However, a more thorough assessment discovered that the two workings were actually
located near the headwaters of Swamp Creek which joins the North Fork of Agnes Creek downstream of the
aquatic sampling location.
The Company Creek aquatic sampling location (CoC-1) is situated approximately eight miles downstream
of a relatively small mineral prospect. The mineral deposit is noted to be situated on the "Holden trend,"
and was documented to contain copper and silver. The concentration of mineralization was noted to be
. higher than found at the Holden Mine, but the physical location near a ridge top limited the potential for
development (Church et al., 1984).
4.2.2 Railroad Creek Geology and Mineral Resources
Referring to Figure 4.2-4, the geology of the Railroad Creek watershed generally consists of bedrock
overlain by unconsolidated to semi-consolidated glacial, fluvial, lacustrine, and colluvial deposits of silt,
sand, and gravel (Cater and Crowder, 1967). The geologic basement rocks (bedrock) consist primarily of
massiye granitics and metamorphosed sedimentv rocks including hornblende, gneiss, and schist. The
granitic rocks are predominant in the eastern portion of Railroad Creek. Bedrock outcrops at the surface
along the valley walls and ridge lines, and is encountered at depths ranging from the ground surface to
greater than 100 feet deep in the valleys. The granites are primarily biotite-hornblende quartz diorites, and
the metamorphic rocks generally consist of hornblende, schist, and gneiss (Church et al., 1984).
In terms of the structural geology, the bedrock is, in places, highly fractured, folded, and faulted. However,
referring to Figure 4.2-5, the faults have been mapped by others as being generally limited in lateral extent
(Cater & Wright, 1957 and 1967).
The Railroad Creek watershed contains a relatively large number of economic mineral deposits, in addition
to the Holden Mine, which have been developed as either prospects and/or mines. Referring to Figure 4.2-4
and Table 4.2- 1, 2 1 prospects and/or mines were identified in the watershed; records were found for 18 of
the workings (USGS, 1998). Four prospects were noted on the maps near the mouth of Railroad Creek for
which no records were located; one of the prospects was observed in the field to be near surface water
sampling station RC-8.
Based on the records reviewed, one of the prospects located northeast of Holden Lake, noted as the Mary
Green (a.k.a. Martin Peak) was operated by Howe Sound Company in the late 1950s. The prospect included
several adits approximately 370 feet in length with several prospect pits (Church et al., 1984). Ebbutt, 1938,
documented the presence of a 280-foot-long drift, but with "no mineralization in evidence that would
approach being commercial." The principal mineralization was reported'as copper and silver. Observations
during the RI disclosed a single mine opening, a limited waste rock pile, and no indications of seepage
and/or drainage from either the mine opening or waste rock pile.
Three other prospects and/or mines were reported between Holden Lake and Railroad Creek. The owners
and/or operators were not found. One of the deposits, known as the Ideal, reportedly was developed for
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