Marking survey-stations

[Andy Waddington on Cave Surveying]

On Wednesday 2003-10-22 12:15, Roger Johansson typed:

> I've seen and heard of several ways to [mark permanent survey
> stations], for example cairns, carbide
> soot markings, bolts, etc, but they all seems to have some major
> disadvantages. Cairns will not withstand running water or clumsy cavers.
> Bolts are time-consuming to place and might make the cave look littered
> (carbide-soot looks even worse).

Paint splotches suffer similarly from making the place look a mess and
certainly, on the surface, they don't survive indefinitely. Cairns can be
great for survey stations during a survey, but as you say, are very
vulnerable between survey trips.

La Sistema Purificacion in Mexico has been surveyed over many years
(it was 1981 when I was there, and it was already a huge system). Projecto
Espeleologoca Purificacion used drill holes to mark survey stations. A
driver much like those used for self-drilling anchors was used with a drill
of diameter around a quarter inch to make a hole up to an inch deep.

These holes are not obvious to a casual caver, so don't litter the cave
appreciably. However, such a hole is very obviously artificial, so that
anyone with existing survey data can relocate such a mark very
readily and be quite certain of its identity as a survey station. Since the
drill diameter is small, you can be quite sure that it is not just a place
where someone started to place a bolt and then changed their mind...

> Is there any better way to do this? And should one be able to remove the
> station-markers in the future when the survey is considered to be finished?

By putting a highly visible plastic tag in the hole, the survey station
becomes much easier to find (I believe the Easegill survey used tags
intended to mark cows' ears :), but these can be removed when an area
is considered fully surveyed. The unobtrusive holes remain.

In Austria we have used equipment that is to hand, which is usually a
drill intended for placing bolts. Obviously, in some places we need to
place bolts for pitches, and re-using these for survey stations saves
making a separate hole - beware that if more bolts are placed later
to improve the rigging, it may become unclear which one is the
survey station !

Some ideas for you - no doubt there are many others.

Andy