SANDSTONE
[ Visible from both Highway 50 lanes ]
N38” 36.206 W092” 28.816
Sand stone (sometimes called arenite) is a sedimentary rock composed of mainly sand size minerals or rock grains. Most sandstone is composed of quartz and/or feldspar because they are the most common minerals in the Earth’s crust. This is known as the Ordovician-age (485.4 to 4433.8 Million years ago) Sandstone Formation. The bedrock to the east and west of this sandstone is the Ordovician-age Jefferson City – Cotter Dolomite. Most likely this formation is what is known as a paleokarst formation where there was some type karst formation within the older Jefferson City-Cotter Dolomite, such as a cave, sinkhole, or spring that was eventually filled in by the younger St Peters Sandstone and appears as it does today. The thickness varies from one foot to forty feet, sometimes within a few yards. Like sand, sandstone may be any color, but the most common colors are tan, brown, yellow, red gray, pink, white and black. The tan or yellow is from a blend of clear quartz with the dark amber feldspar (granules of Celica) in the sand. Small amounts of iron give the particles the reddish to brownish tint ranging from pink to dark red. Manganese will give the particles a purplish hue. A fresh surface is, as a rule, nearly pure white, to light brown in spots.
The formation of sandstone involves two principal stages. First a layer or layers of sand accumulate as a result of sedimentation, either from water (as in a steam, lake, or sea) or from air (as in the desert). After it has accumulated it becomes sandstone when it is compacted by pressure of overlaying deposits and cemented by the precipitation of minerals within the sore spaces and grains. The most common cementing agents are silica and calcium carbonate, which are often derived either by dissolution or from alteration of the sand after is buried
Since sandstone beds often form highly visible cliffs and other topography features, certain colors of sandstone have been strongly identified with certain regions. Rock formations that are primarily composed of sandstone usually allow percolation of water and other fluids and are porous enough to store large quantities, making them valuable aquifers and petroleum reservoirs. Fine grained aquifers, such as sandstone, are better able to filter out pollutants from the surface than are rocks with cracks and crevices, such as limestone or other rocks fractured by seismic activity.
Sandstones are clastic in origin. They are formed from cemented grains that may either be fragments of a pre-existing rock or be mono-minerallic crystals. The cements binding the grains together are typically calcite, clays, and silica. Grain size in sands are defined (in geology) within the range 0.002-0.079 inches.
The sand produced by this sandstone at this location is very fine and similar to the lower end of the size range. Due to this smaller size it is easy to relocate. Note the erosion of the cut and the dispersion of the eroded sand in the road ditch and being washed away.
[NOT SUGGESTED OR NECESSARY TO STOP] This road way cut is located on the Westbound Land of the Duel Lanes of US Highway 50 on the north side of the highway. Highway 50 is a very busy and heavily traveled East/West route through Missouri. This site is very visible from both lanes, and the conformation question answers are very evident – so there will be no need to stop. The answers can be obtained as you drive safely by, and the documentation.
To claim this Earth Cache pleas answer the following questions:
- What is the dominate color of this sandstone cut? ________________________________________
- What is your estimate on the height of the cut, in the center? _______________________________
- What gives sandstone its color? _______________________________________________________
E-mail answers to the cache owner for verification.
Information was collected from “Wikipedia” Free Encyclopedia, Contacts with Tina Grothoff of MoDot, George Davis Geologist for MoDot, Fletcher Bone Geologist Missouri Geological Survey Rolla, Mo., Moniteau County USDA Soil Conservation Service.