Earth cache lesson
Sandstone is a wide ranging description for vastly different types of slowly deposited stone. Below are three descriptions of sandstone, however only one of the types of stone is here.
Read the types of stone and search block at the GZ to find out which one this block was carved from.
Yellow Sandstone
This is a highly silica rich stone and is fine grained. Portland stone falls into this category and this type of stone is a popular building material since it is easily carved and holds its shape over long periods of time.Yellow Sandstone has been used for domestic construction and housewares since prehistoric times, and continues to be used. Sandstone was a popular building material from ancient times. It is relatively soft, making it easy to carve. It has been widely used around the world in constructing temples, homes, and other buildings. It has also been used for artistic purposes to create ornamental fountains and statues. This type of stone can be very smooth to the touch and as water runs over it can be 'polished' to an almost marble finish. This will be blonde in colour and can be bleached white in direct sunlight
Grey Sandstone
Often called mudstone, grey sandstone is a very fine grained stone and is common in this area and further north where ancient aluvual deposit formed slowly on deltas of rivers. This type of stone is usually smooth and has no defined lines in its composition. Also, mudrock is a fine grained sedimentary rock whose original constituents were clays or muds. Grain size is up to 0.0625 mm (0.0025 in) with individual grains too small to be distinguished without a microscope. With increased pressure over time the platey clay minerals may become aligned, with the appearance of fissility or parallel layering. This finely bedded material that splits readily into thin layers is called shale, as distinct from mudstone.
Red Sandstone
Red is the rough side of the family of stones. It is made up of large grains and is a poor buliding stone since it usually has very obvious lines where different layers have been deposited and tends to split easly along these fissures. If you are looking at red sandstone you will be able to see clear lines across the rock where softer parts of the rock have 'washed away' during ersosive episodes. Because of the hardness of individual grains, uniformity of grain size and friability of their structure, this type of sandstone is excellent materials from which to make grindstones, for sharpening blades and other implements. Non-friable sandstone can be used to make grindstones for grinding grain, This stone will be rough to the touch and will have a definite redish hue.
Questions (please message me the answers, do not include them in your log)
1) Look at the rock and find a part not covered in moss or lichen. Describe how the bare rock looks and feels.
2) Using the information from Q1 and the descriptions above, tell me whether this block is grey, yellow or red sandstone
3) Typically a sandstone will weigh 2 to 2.5 tonnes per cubic metre, have a rough measure of this rock and tell me what do you think this rock will weigh in tonnes?
Optional
4) What show did you see? Was it any good?
If you feel willing and able please post a photo of yourself, your GPS, or something interesting close to the GZ (not the rock itself)
Thanks for visiting this cache and I hope you enjoyed the show.