2011-09-19_REVISION - M1982155 (17)

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gneiss, and some sandstone fragments. Most of the deposit contains "decomposed" granite. Although not really decomposed, the Pikes Peak Granite tends to fragment into granite pebbles and gravels with a high proportion of feldspar that gives the gravel its characteristic earth tone colors of orange, yellow, and red. Quartz and small flecks of mica and hornblende are also present, but the gravel is composed mostly of feldspar crystals. The deposit was formed as a result of erosion from the Pikes Peak area located a few miles to the west. These deposits are probably only a few tens of thousands of years old and were likely created toward the end of the last ice age. Heavy runoff from the mountains created vast pediments (relatively flat surfaces at the base of mountains) of this material that extend, in places, nearly as far south as the Arkansas River, but are mostly found within about 10 miles of the Pikes Peak mountain complex. Subsequently, drainages off the mountains dissected these pediments creating broad valleys. The removed gravels were washed to the Arkansas River, but what was not eroded away remains on the high, usually gently sloping remains of the former pediments. The gravel deposit in the amendment area is similar to that found and previously mined on the east side of Charter Oak Ranch Road. The deposit ends rather abruptly a short distance south of the north permit line, same as in the existing permit area. To the south, the deposit deepens rapidly to about 30 feet or more. The gravel deposit rests on top of a shale bedrock material that extends under the current Fountain Pit permit and amendment areas. In general, the gravel deposits contain an extremely low amount of fines and therefore produce a rather sparse vegetation cover. Where the deposits are exposed on slopes at the edge of the valleys, shallow fairly steep sided gullies may form as the highly erodable gravel is washed away. On the more flat areas of the deposits a few to several feet of very good loamy soil and overburden can be found. This soil and overburden is primarily derived from aeolian deposits of clays and silts carried in from the east on dust storms during dry periods after the end of the last ice age. Some of the soil and overburden contains small, sand sized fragments of granite as well, indicating that after the deposition of the coarser rock, pediment construction continued but with more gentle flows from the mountains that carried clays, sands, and silts. The fines from the mountains mixed with the fines from the prairies to produce a rich soil and overburden with loamy texture on top of gravel. In the amendment area, as has been found in the main pit, topsoil and subsoil (or overburden) do not actually differ that much except with respect to organic matter content. Additionally, beyond the more level pediment surface where topsoil depth is typically between four and eight inches, soil of any kind is extremely limited or non - existent as the surface is primarily composed of the gravel deposit. Therefore, as far as a plant growth medium is concerned, the primary source is the deep, more loamy soils and overburden over the large gently sloping land on the uplands above the gravelly slopes. To the north and west of the amendment area is Fort Carson Military Reservation. Immediately west of the site is a former gravel pit that was apparently operated by Fort Carson to use on the military reservation property. The area of operation and depth of the pit is similar to what is Fountain Pit M -1982 -155 DRMS 112 Permit Amendment Page 5