As you stand the point given on the listing you will notice a mixture of new and old building and pavements.
I’d like you to read the description of the types of stone below and look around to tell me where they have been used in the construction of this pedestrian area.
You may also need to read the section on weathering and erosion to help identify which rocks are which since some are much newer than others.
The area you need to search is flat, even and accessible from close by parking for people of all mobility.
Sandstone is of course a sedimentary rock composed of small sand-size grains of mineral, rock, or organic material. It also contains a cementing material that binds the sand grains together and may contain a matrix of silt- or clay-size particles that occupy the spaces between the sand grains. Sandstone is one of the most common types of sedimentary rock and is found in sedimentary basins throughout the world. It is often mined for use as a construction material or as a raw material used in manufacturing. When used in construction it tends to have very few lines or marks in it and is all of one colour. It is a very strong, hard material and will weather very slowly. It can be yellow, red, grey and many other colours.
Granite is a coloured igneous rock with crystals large enough to be visible with the unaided eye. It forms from the slow crystallization of magma below Earth's surface. Granite is composed mainly of quartz and feldspar with minor amounts of mica, amphiboles, and other minerals. This mineral composition usually results in dark mineral crystals easily visible throughout the rock. Pink granite, like other granites is an intrusive igneous rock typically containing feldspar, quartz, mica & amphibole minerals. This variation contains potassium feldspar plagioclase that gives the granite a distinctive pink colour as opposed to other variants which can be white, grey, dark brown or even black.
Weathering is the breakdown of rocks at the Earth’s surface, by the action of rainwater, extremes of temperature, and biological activity. It does not involve the removal of rock material. There are three types of weathering, chemical, biological and physical,
Physical weathering occurs when rock is subjected to changes in temperature. Freeze-thaw occurs when water continually seeps into cracks, freezes and expands, eventually breaking the rock apart. This can happen at a microscopic level as well as in larger visible cracks, resulting in grains or even small rocks breaking away.
Chemical weathering is caused by rain water reacting with the mineral grains in rocks to form new minerals (clays) and soluble salts. These reactions occur particularly when the water is slightly acidic. The way to identify this type of weathering is when you notice smooth, rounded parts of rock, especially low down, where more water will have passed over it.
Biological weathering is where organisms have affected the rocks. There are many ways this can happen, for example, roots of a tree could force gaps, lichen could grow on the rock, animals could bore into the rock and bacteria could be breaking down a rock as food.
Erosion is the process by which soil and rock particles are worn away and moved elsewhere by wind, water or ice. Weathering and erosion acting together will break down even the hardest rocks and transport particles away from it resulting in a change in how the rock looks and feels.
The main focus of this EarthCache is to identify the two types of rock described above in the construction of these buildings and walkways, tell me where they are and to identify how they have or have not been weathered/eroded.
So to the requirements to log this cache. All the answers can be found within 10m of the GZ given.
You are looking to identity two types of granite and sandstone in two different stages of weathering/erosion.
1) Find and describe two types of granite, tell me where they are and how they look and feel.
2) Do these granites show any signs of weathering? Please explain how you came to this conclusion.
3) Find two different places where there is sandstone in different stages of weathering/erosion and describe where they are and how they look.
4) Please explain why some sandstone is weathered/eroded and some is not, giving reasons for your answers. If you feel willing and able, please include a photo with your log but try not to give any answers away.
Please feel free to log your find and send (via email or the message system) your answers at the same time.
I look forward to reading your logs.