Quote from RHB reflector site:-
"Thorpe Fell Top and Cracoe Fell have been on our survey agenda for
some time and we finally had a go at it last week.
We did the Survey in 3 parts:-
- View from Thorpe Fell Top to Cracoe Fell.
We set up the Leica Level on its tripod about 150m from Thorpe Fell
Top so that it was level with the base of the trig. and then viewed
Cracoe Fell. We took two sets of digital photographs of each hill
from which we could measure the height difference. In fact you cannot
see the exact summit location of Cracoe from Thorpe as it is on the
rock base of the obelisk on its NW corner. (We subsequently "staffed"
around the rock on Cracoe to work out a correction for this). These
photos showed that Cracoe was 2.0+/-0.2 metres HIGHER.
- View from Cracoe fell to Thorpe Fell Top
We managed to perch the Level on its tripod on the NE corner of the
rock on which the obelisk sits, staff to the summit of Cracoe and
also photograph as above to Thorpe Fell Top. Visually the horizontal
level line was about one trig point height above the top of the trig.
Again from the photos we measured Cracoe Fell to be 1.9+/-0.1m
HIGHER. In this measurement and 1), because we are surveying over a
distance of about 1.7km, we made a correction of 23cm for earth
- Line Survey from Cracoe fell to Thorpe Fell Top.
This was the serious bit. We “triple wire” line surveyed the whole
1.7km distance. The results showed that Cracoe Fell was 1.833m
HIGHER. This took a long time and so we did not have a chance to
repeat in the reverse direction to get a closing error. However, we
have a lot of experience at this now and we find we get roughly a 1mm
error for every reading set. In this case we had to do 27 sets so I
would expect the error to be no more than +/-0.030m. No corrections
for earth curvature are needed here.
Three independent sets of measurements are consistent and showing
unequivocally that Cracoe Fell should be the new Marilyn with a
height of 507.8m. (from FB on Thorpe Fell top at 506.2m OS4)
Unfortunately Thorpe Fell Top disappears from the list!!! A shame
really since I wrote an article on this hill in MARHOFN 2005 as my
1000th Marilyn which must now move to Yarlside climbed on 15 August
The col/bwlch/bealach between the hills his a wide area and would
take a lot of survey effort to find its “exact” position. So in the
line survey we came down by the wall running NE on the “left” side of
the line between the two hills. There is a path there that gave us
better level and staff placements. Before ascending we dropped 31.6m
so this raises the question “Do we have two Deweys here?” I think we
dropped below the true col and if the lowest measurement had
indicated a drop significantly less than 30m in our survey, then we
would be sure Thorpe Fell was NOT a Dewey. However, it does look very
close but I think my money would be that Thorpe Fell would NOT