Sandstone is a sedimentary rock which is composed mainly of sand-sized minerals or rock grains.
Most sandstone is composed of quartz or feldspar. This is because these are the most common minerals in the Earth's crust. As sand can be many colours – sandstone also may be any colour, The most common colours of Sandstone are brown, yellow, red, grey, white, black and pink. The colours of sandstone typically relate to region that they are found in. Some of the sandstone in Utah (USA) is coral pink. This is because the sandstone contains grains of quartz with a hematite coating providing the orange and pink colour.
Sandstone beds often form highly visible cliffs and other distinct features, certain Rock formations that are predominantly composed of sandstone usually allow the percolation of water and other fluids being porous enough to store large quantities of water, making them valuable aquifers. Fine-grained aquifers, such as sandstones, 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.
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Sandstones are clastic, which means they are made up of fragments of rocks or other materials such as crystals. They are formed from cemented grains that may either be fragments of a pre-existing rock or be mono-minerallic crystals. The cements binding these grains together are typically calcite, clays, and silica.
calcite cementation occurs in meteoric realms (freshwater sources), the cement is produced by the dissolution of less stable aragonite and high-Magnesium calcite.
Clay Cementation is a fine-grained natural rock or soil material that combines one or more clay minerals with traces of metal oxides and organic matter.
Silica cementation can consist of either quartz or opal minerals. Quartz is the most common silicate mineral that acts as cement. In sandstone where there is silica cement present, the quartz grains are attached to cement, which creates a rim around the quartz grain called overgrowth. The overgrowth retains the same crystallographic continuity of quartz framework grain that is being cemented. Opal cement is found in sandstones that are rich in volcanogenic materials, and very rarely is in other sandstones
Grain sizes in sands are defined (in geology) within the range of 0.0625 mm to 2 mm.
Clays and sediments with small grain sizes not visible with the naked eye are typically called argillaceous sediments.
Rocks with larger grain sizes are typically called rudaceous sediments.
Sandstone Formation: It is typically formed in two stages.
- A layer or layers of sand accumulates as the result of sedimentation, either from water (as in a stream, lake, or sea) or from air (as in a desert). Sedimentation occurs by the sand settling out from suspension; i.e., ceasing to be rolled or bounced along the bottom of a body of water or ground surface.
- Once it has accumulated, the sand becomes sandstone when it is compacted by the pressure of overlying deposits and cemented by the precipitation of minerals within the pore spaces between sand grains.
To claim this cache:
Please answer the following questions and either email or message me the answers. You may log the cache immediately as per the EarthCache guidelines. I will contact you if I have issue with your answers.
- What is the average thickness of the stone bands in front of you.
- What is the predominant colour of the rock?
- Touch the rock is it soft or hard and brittle?
- I have mentioned above that grain sizes in Geology range from 0.0625 mm to 2 mm. On a scale of 1 to 10 where 1 = 0.0625mm and 10 = 2mm how would you rate the grain size?
- What do you think the cement is that is binding the grain? A) calcite. B) clays or C) silica?
- Finally how high is the bank which contains rock?
Optional but desirable: Take a picture of yourself or your GPS beside the bank.