To continue the debate about surveying a little longer I probably need to
give a bit more information about my approach which is to combine a number
of methods to analyse and understand mining landscapes. This ranges from
desktop mapping using air photographs and historic maps, including
geological maps, to GPS mapping which is very useful for putting detail onto
big landscapes in a short period of time, and analytical earthwork survey
for small detailed areas.
As I presented to the Yorkshire Dales Archaeology Day at the weekend the
mainstay of my recent work is GPS survey. In this case I have been working
in Arkengarthdale where lead mining remains are mostly found on the high
moorland. This is a landscape mainly dating from the 18th century containing
shafts, dams and water leats. Ore dressing is present but almost all of the
dressing tips have been destroyed by reworking, which went on from the early
19th century. This means that there are very few sites that would benefit
from detailed analytical earthwork survey, but it is an option that I have
available and later on in the project key sites will be selected for this
treatment. They will therefore form detailed islands within the larger
landscape survey. So far I have recorded an area 1500m x 700m containing
over 100 shafts in about 6 sessions, to do the whole area as an analytical
earthwork survey would have taken more like 6 weeks or longer and without
funding would not have been possible.
Plotting the landscape at a scale of 1:2500 proves to be a useful scale when
combining the surface survey with underground surveys. This is something
that has not been mentioned so far. When examining mining landscapes it is
essential to include the underground part of the landscape, either with new
survey data or by reference to historic maps and plans. So far in
Arkengarthdale we have added about 6km of new underground survey to the
surface mapping. As with the surface survey the underground survey is
produced at both a landscape level, by recording the centre line of levels
using compass and tape survey, and detailed surveys of small areas either as
tape surveys or plane table surveys produced with the aid of a laser disto.
These detailed surveys are comparable to the analytical earthwork surveys on
the surface.
You will see that this is therefore a multi layered and flexible method of
approaching mining landscapes. And so far it is proving to be very
effective.
A comment was made about a GPS survey plotting the position of a water leat
4m away from where it was shown on a map. Could I suggest that there are
many reasons why that may have been the case and it is likely that any error
would not just be due to the GPS. In rural areas OS maps can have errors of
up to almost 3m at a scale of 1:2500 and 4m at 1:10000, sometimes even more.
As I said in an earlier message the scale at which the map is plotted
affects how important that error is. If it is too small to plot at the
chosen scale then it is not important. This is a problem that people often
have when learning to survey. Thinking that everything has to be measured to
the nearest mm, unless you are producing an engineering drawing is not
needed.
Mike’s suggestion of having a seminar on “surveying, recording, analysis and
the final product” would be an excellent idea and would allow us to present
our different approaches. This may well lead to the recognition that
different approaches have a lot to offer. I think that this will definitely
the case when it comes to the analysis and final product.
Martin Roe
President, Northen Mine Research Society,nmrs.co.uk
Conservation Officer NAMHO, National Association of Mining History
Organisations, http://www.namho.org
Lead Mining in the Yorkshire Dales,
http://www.martinroe.pwp.blueyonder.co.uk
Meerstone Archaeological Consultancy
http://www.martinroe.pwp.blueyonder.co.uk/meerstone.htm
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