| Beaches
Beaches and sand dunes are often the easiest places for
the beginner to start a sand collection. They are usually easy to access
and sand is plentiful and simple to collect, well, at least
when the tide is out! While not
always as
productive as sand and gravel pits, with some carefully
searching many different grades and colours of sand can be
collected. Sand dunes, however, do tend to have a rather
limited range of sands available for collecting.
At a recent trip to a small beach near Dunbar in East Lothian,
I was able to collect six different samples, all with
slightly different shades and compositions. Another trip to
a similar beach, just a few miles along the coast,
produced eight different samples. I've also found that as
you gain experience you will find that the number of samples
you can collect increases and it is often worthwhile
re-visiting locations you visited earlier in your collecting
career.
When visiting beaches one of the first places to collect
samples from is the top of the dunes, where wind blown sand
will have settled. This will be very fine and in many
instances will also be dry - saving you having to dry it, sieve out
the bugs and others stuff! Organisms are usually absent in
surface layers although grass and root fragments may need
sieved out. Older dunes, usually located further inland,
will have similar sand but of different colours due to
weathering and leaching over the years. The next place to gather sand is at the foot of the
dunes, at the edge of the high-tide line. Here the sand may
be comprised of larger particles as well a shell and other
fragments. Sand can also vary quite widely from one end of
the beach to the other, particularly if the beach runs
parallel to the prevailing wind direction. I would always
advise examining the whole length of a beach. A good way to
walk a beach is in a zig-zag pattern, searching between low
tide and high tide. With wind-blown sand it is sometimes
possible to encounter pockets of different sized grains of
sand on either side of a suitable obstacle, such as a
pebbles, beach debris or similar objects.
Gathering samples from between high and low tide lines
can be quite productive, although what can be found will
very much depend on the individual beach and local
geological environment. One point of note when collecting in
this tidal zone is that there may be considerable living
organic matter in the samples and washing is very much
advised. A good tip is only to collect from the top 10mm or
so. This leave the resident animals and insects in situ.
The sandy areas of beaches are not the only places to
look for samples. Even in areas where pebbles, boulders and
even volcanic bedrock dominate, isolated patches of colourful and
interesting sand may be found often made up entirely of the
tiny fragments of the local rock. It's also worth investigating
where small streams flow across the beach. When looking for different sands at the beach, pay
attention of areas where the colours and shades of the sand
change, particularly dark areas, which may indicate where
heavier minerals have settled.
Paying attention to local beach geology can often be
fruitful. Even if you do not have any great understanding of
the rocks you come across, it is sometimes enough just to
recognise that the local rock outcrops have changed. A
recent example was Coldingham Beach near Eyemouth in East
Lothian. Here the geology at either end of the beach is
quite different and the sand is correspondingly varied as
well.
Before planning a trip to a beach, particularly if
travelling some distance, it makes good sense to check out
the tide times before leaving. Opportunities for collecting
samples can be severely restricted when the tide is in. Not
only are parts of the beach itself below water but you may
also find that other inlets and coves are also out of reach.
There are plenty of sites on the Internet where up-to-date
and tide tables can be found. |
