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Sand collecting methods
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This page : Introduction : Collection
: Preparation : Record
keeping : Storage : Sand
scans |
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When I first started to collect sand, I made subjective decisions as to what
materials I would consider as suitable for the collection. In many cases it
seems obvious whether a particular material should be considered as sand or
not, but exactly where to draw the line between silt and sand, or between
sand and gravel is not always so easy. Technically, sand is defined as
material from 0.002 to 2.0 mm particle size, produced by the weathering of
rocks. This definition would exclude the material that makes up many of our
beaches because it consist of shell fragments rather than rock particles yet
almost everyone (myself included) would class this as sand.
For my collection, I decided that the limits to what I would collect would be determined by my methods of collection, preparation and storage rather than by any other rules. I only collect material which can be scooped up with my fingers so this limits the choice of material to particles which are loosely aggregated and of relatively small size. I never actually select which individual particles are picked up. On return home I always wash the samples in water and discard any material which floats on the surface (mainly organic remains), and anything which does not settle to the bottom of the container within a few seconds (clay and silt). Washing will also remove anything which is soluble in water. I store my samples in specimen tubes which measure 25 mm in diameter so this gives a physical limit to the particle size which would fit into the tube. In practice, none of the samples I have collected come anywhere near the size where the particles would not fit into the specimen tube. However, I do not limit my collection to a particle size of 2.00 mm. The methods and materials I use to collect, prepare, store, display and record sand samples are as follows:
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To collect a sample I use my fingers to scoop up a small amount of sand and
this is then placed into a suitable container. If I am likely to visit
somewhere where I could collect sand I take some small polythene bags
with me. I also keep a supply of these in the car so they are always available when I
travel. (Any other container can be used provided that it is sand-proof and
clean - I have made use of a wide range of containers when the need
arises.)
I collect sand from anywhere where it occurs naturally. On beaches in particular, very different types of sand can be found even in places quite close together. Small bays or inlets commonly have their own type of sand. On some beaches it would be possible to collect numerous different looking samples but I usually restrict the number of samples from any one site either to a single sample or a small number to show the range of variation. As yet, I have collected very few types of sand that have been processed commercially. A wide range of specially prepared sands are used in building, horticulture, glassmaking, sand-blasting etc. and I am sure that they would make a very interesting collection.
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To prepare a sample of sand for the collection I treat it in the following
way:
Working at the kitchen sink I first tip the sample out of the bag into a jam-jar of water. Some samples settle cleanly to the bottom of the water and all I do is rinse them a few times with water. Others contain clay, silt or organic material which remains suspended or floating on the surface. I carefully tip off the dirty water then refill the jar allowing the force of the water from the tap to stir up the sand. I allow it to settle for a few seconds then tip off the liquid again. This process is repeated until the water remains relatively clear. I then place a square of finely-woven cloth over the neck of the jar and, holding it tightly in position I invert the jar, swirling it gently so that all the sand is washed onto the cloth. By slightly raising the jar while holding the cloth in position it is possible to allow the water to drain away quickly without losing any of the sand. The pieces of cloth I use are cut from old bed sheets and these seem to be fine enough to retain the smallest sand particles When most of the water has drained away the jar can be pulled completely out of the cloth and by bringing the edges of the cloth together, the sand sample is retained in a pouch of cloth. The pouch of wet sand (together with the empty bag on which the data is recorded) is then stood on several sheets of newspaper and opened out. After a few hours I usually transfer the sample to dry newspaper and leave it until it is completely dry, stirring occasionally to speed up the drying process.
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For each sample I record the following information on a computer database.
Number: Each sample is given a reference number. The first two
digits are the year of collection and this is followed by the number of the
sample. (e.g. 9820 = the 20th sample collected in 1998)
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It is always interesting to examine sand with a hand lens, or better still, a binocular microscope. With suitable equipment it is also possible to take excellent photographs and enlarge them to show details of the constituents. Another method that I have found very useful and much easier, is to use a flat-bed scanner to scan samples directly. Further details and examples are shown on the Sand scanning methods page. Top ^ |