The British Mountaineering Council (BMC) has published an interview that
Graham recently gave about the surveys that G&J Surveys have conducted over
recent years. The original article and a
link to it on the BMC website appear below.
Moving
mountains: meet the men who are rewriting the tick lists
 |
| The group use survey-grade GPS equipment to accurately find the height of mountains |
Creag na Caillich was recently dropped from the list of Munro Tops after
a small team of independent surveyors proved it to be under 3,000ft high. So
who are G & J surveys, and why does their work matter to peak baggers?
If you’re working your way through the Munros, the
Corbetts or any of the other seemingly endless mountain tick lists, then you’ll
want to keep a close eye on the efforts of G & J Surveys. This small team
of three friends - John Barnard, Graham Jackson and Myrddyn Phillips - have
dedicated the last few years to exploring the hills with a very particular aim
in mind. Using survey-grade GPS equipment, they measure the height of hills
with incredible accuracy, often playing havoc with the official checklists as
they go. Remember when the Fisherfield Six became the Fisherfield Five? That
was G & J surveys. More recently they proved that Creag na Caillich can’t in fact
claim Munro Top status. So what motivates these three hill
enthusiasts to go around measuring mountains? We caught up with Graham Jackson
to find out.
Why is it
that so many of the mountain heights recorded on Ordnance Survey maps are
incorrect?
It isn’t that they aren’t correct; it’s just that
there is some uncertainty in the measurement. The OS is charged with mapping
the whole country at least once every five years, and that’s a huge task. They
do it by flying a plane over the terrain they are mapping and photographing as
they go. Then they turn the plane round and retake the images. When they feed
two images taken from a different angle into a machine, that gives a 3D picture
and from that you can measure height. That technique is accurate to plus or
minus three metres, so if you’re a map user then it’s perfectly fit for
purpose. It doesn’t matter if a mountain is shown on a map as 3,000ft high or
3,010ft high - you can still get to the top of it.
So why is
accuracy suddenly more important?
It’s really down to hill lists. The majority of
lists have some kind of criteria - so Munros, for example, are all 3,000ft or
more. If you have a 915m height on a map then that hill will be classed as a
Munro - but it might in fact be 918m or 912m. People with an interest in peak
bagging want these lists to be accurate.
I hear
you’re a peak bagger yourself - did that help spur your interest in measuring
mountains?
Yes, the walking group I’ve been a member of since
1989 has been ticking off Munros since the early 1980s and that definitely got
me thinking about it. Sometimes you’ll start to climb a list of hills and you
get halfway through when the authors come out with revisions that they’ve taken
from the maps. You end up thinking ‘there must be a better way than this’.
How did G
& J Surveys get started?
Again, it was through our walking group. When
you’re in a pub you start talking about things and inevitably the conversation
will arrive at how it’s possible to know the highest point of a hill because
they have so many humps and bumps on them. After one of these conversations
back in 2006, John [Barnard] went away to research this some more and discovered
we could work this out using an Abney level - basically a small spirit level.
We got a little more into it and bought a surveyors’ level and staff, and then
finally in 2008 John said that we could do with a survey-grade GPS and that’s
when it all really got started.
Tell me a
bit more about the technology you use to measure mountains - how accurate is
it?
We use survey-grade GPS equipment that links into
a network of OS base stations. The system is called differential GPS and you can get down to amazing
levels of accuracy - literally a couple of centimeters. By the time you get to
that point, you’re worrying about where the vegetation stops and the mountain
begins.
What do you
count as your most important discoveries?
We reclassified two Munros - both of which
unfortunately went down rather than up, so there are now 282 Munros rather than
the original 284! The first was Sgurr nan Ceannaichean and
the second was a hill called Beinn a’Chlaidheimh in the
Fisherfield Forest. That last one meant that the famous Fisherfield
Six became the Fisherfield Five.
The hill that made the greatest impact was probably
Mynydd Graig Goch in Snowdonia, which had been listed as under 2,000ft and was
actually just above - making it a new Welsh ‘mountain’. It was the time of the
banking crisis, there was doom and gloom everywhere, and while everything in
the world was going down here at least was something that was a bit of quirky
good news.
Another significant one was back in 2010, when we
discovered that Glyder Fawr was over 1,000m and
therefore had to be added to the Welsh 1,000m challenge hill race.
What do peak
baggers think of your work - do you get any grumpy compleaters who don’t like
the fact that you’ve demoted one of their mountains?
A lot of people are really supportive of what we do
- one chap called Alan Dawson has bought his own kit so that he can help out,
and some guys in Ireland who we visited recently are starting to measure the
hills over there. Others don’t believe that what we’re doing is as accurate as
claimed, and of course some people take it badly when a hill that they have
climbed is demoted - but that’s why it’s so important for those lists to be
accurate, because a lot of people use them.
How
‘official’ is the work that you do?
We have a good working relationship with the
Ordnance Survey and the SMC will take any changes we find provided that the OS
verifies them. What happens when we measure a hill is that we submit our files
to the OS, which processes them using their software and confirms the results
for us.
When you set
off to survey a mountain that you think could be a candidate for promotion or
demotion, is there a frisson of excitement there?
It is exciting! Both John and I studied chemistry
at university and come from a background involving measurement, and having that
background you’re always motivated to see if there’s something that can be done
better and whether measurements will help.
How much
importance do you place on tick lists yourself?
I’ve done the Munros, the Corbetts and the Grahams,
and I think that working your way through a tick list focuses the mind - if you
don’t have a focus in view then you don’t tend to do as much. But are hill
lists important to enjoying the uplands of Britain? Not really. The things that
stick in my mind from being in the hills are individual moments…like walking in
the Mamores and seeing a golden eagle gliding right by me, or being in the
middle of Rannoch Moor on a remote Graham when a flock of snow buntings flew
by. Things like that enrich the experience more than just meeting an
objective.
But you’d
still consider your efforts to make the lists more accurate important?
Personally, I think that if you’re going to have a
list based on any criterion then it should be as accurate as it can be or it’s
a pointless exercise. There is a lot of discussion about this sort of thing as
well. One of the first hills that John and I first measured was Birks Fell in
the Yorkshire Dales and there was so much controversy on forums and on social
media about where the summit was. We went up there with a level and staff and
found the highest point incredibly easily. Why pontificate about it when you
can just go up there and measure it?
What peaks
do you have in your sights next?
We usually get together in December and plan for
the year ahead. In winter we choose objectives that are nearer and can be
completed in a short day, so we might just keep our hand in by nipping into
Wales and measuring a hill that’s borderline on the list of HUMPs. Our broader
objectives are to finish some of the hills on the Munro/ Corbett and Corbett/
Graham borderlines, working with the SMC. There are some hills in Cumbria we
want to do too, such as Illgill Head which is currently listed as 609m but
could just make it over 2,000ft. Let’s put it this way - we’re certainly not
short of challenges!
Please click {here} to see the
original article published on the British Mountaineering Council website
No comments:
Post a Comment