EDUCATIONAL LOGGING REQUIREMENTS
In order to substantiate your visit and comply with the educational requirement for Earth Caches you have to submit your answers to the following questions to the cache developers via their profile:
For purposes of logging this cache you must answer the following four questions.
TO LOG THIS CACHE AND QUALIFY you need to answer the following questions in an email to the cache owner via our profile on the geocaching website. Any logs not accompanied by an email will be deleted.
1) Approximately how high is the face of the quarry? i.e. How deep have they dug down?
2) At the base of the quarry is a grey material. Break some off and rub it between your fingers. Add water if necessary. Is this clay or silt.
3) Based on the colours of this sample, is the soil well drained?
4) (Optional) Post any pictures that you might think add to the value of this Earth Cache.
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This road lies within the Uitenhage Basin. The basement geology of this area would include Bokkeveld shale. This shale weathers down to silt and clays.
This Earth Cache is concerning the top layer of soil and not the bedrock
Clay is a fine-grained natural rock or soil material that combines one or more clay minerals with traces of metal oxides and organic matter. Clays are plastic due to their water content and become hard, brittle and non–plastic upon drying or firing. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure. Depending on the content of the soil, clay can appear in various colors, from white to dull gray or brown to a deep orange-red.
Silt is granular material of a size somewhere between sand and clay whose mineral origin is quartz and feldspar. Silt may occur as a soil or as sediment mixed in suspension with water (also known as a suspended load) in a body of water such as a river. It may also exist as soil deposited at the bottom of a water body. Silt has a moderate specific area with a typically non-sticky, plastic feel. Silt usually has a floury feel when dry, and a slippery feel when wet.
Clays are distinguished from other fine-grained soils by differences in size and mineralogy. Silts, which are fine-grained soils that do not include clay minerals, tend to have larger particle sizes than clays. There is, however, some overlap in particle size and other physical properties, and many naturally occurring deposits include both silts and clay. The distinction between silt and clay varies by discipline. Geologists and soil scientists usually consider the separation to occur at a particle size of 2 µm (clays being finer than silts), sedimentologists often use 4-5 μm, and colloid chemists use 1 μm. Geotechnical engineers distinguish between silts and clays based on the plasticity properties of the soil, as measured by the soils' Atterberg limits. ISO 14688 grades clay particles as being smaller than 2 μm and silt particles as being larger.
The colours exposed areas in the quarries in the area differ widely. The material is mainly grey but there a number of other colours visible including pink, purple, yellow and red. View also the colours displayed in the other two quarries in this area shown as additional waypoints.
The colours of rock and soils are caused by small amounts of of other elements and minerals and by organic matter. Clay and silt that is poorly drained normally has a grey colour. Organic matter would normally result in brown or black colours.
In the case of these quarries the red, pink and purple colours are caused by iron, iron oxides and iron hydroxides. At Reference Point 1 is a harder reddish vein which is due to iron oxides and hydroxides having crystallised in a crack of fissure. There are also larger red rocks in the quarry which indicate higher iron content.