Wednesday, 19 August 2015

Mapping Mountains – Trimble Surveys – Drumochter Hills

30.07.15  Mullach Coire nan Cisteachan (NN 663 806)    

Mullach Coire nan Cisteachan (NN 663 806)

Mullach Coire nan Cisteachan rises to the east of the A9 as it speeds its way past Dalwhinnie.  The hill has recently been surveyed by Alan Dawson with his Leica RX1250 with the result being that the hill was measured as 914.56m high, as this height is over 914.4m / 3,000ft the hill is a candidate for the Scottish Mountaineering Club (SMC) to consider for Munro Top status.

As the Heighting Project instigated by Iain Robertson on behalf of The Munro Society (TMS) has now finished we thought it appropriate to finalise those lose ends of hills that have not had two hours of data gathered from their high points.  Mullach Coire nan Cisteachan is one of these hills, and our aim was to survey its summit in conjunction with the SMC and TMS.

We met in a large lay-by beside the A9 close to where a track accesses this hill’s north-western slopes.  By the time we arrived David Batty was brewing up and passed a hot mug of tea to Alan Brook who was parked in front of David’s camper van.  Soon afterward Iain Robertson closely followed by Eleanore Hunter, Ian Collie and John Rogerson arrived.  As Bill Wheeler pulled up I had my boots laced up and was walking toward the gate and the track.  I needed a start on these fitter and quicker people, as although all are older than me they seem to speed up the hills.  As I walked over the road I noticed that Rab Anderson was turning into the lay-by, he and Andy Nisbet were representing the SMC and would liaise with Derek Bearhop who instigates any reclassification to Munros Tables.

The track made steady progress up toward the grassed slopes of the hill and wound its way directly up one of the broad north-westerly whaleback ridges that descend from the hill’s western slopes.  The gradient proved sufficiently steep not to tax and within 25 minutes of setting off I looked behind and noticed the first of a number of small figures on the lower part of the track, I thought I stood a chance of gaining the upper slopes before being overtaken.

As height was gained the views opened up and a slight breeze dampened the warmth of the sun, this proved ideal for the ascent.  The track splits higher up near to a small quarry which is indicated on the map, when I arrived at this point I could hear John and Rab’s voices approaching and as I swung left to walk along the track toward the summit of the hill they quickly caught up with me and we proceeded to the summit together.  The others soon appeared with Alan taking over tripod carrying duties which I was thankful for.

On the upper part of the track

Once at the summit we set up the level on the tripod and proceeded to take a number of readings close to the obvious high point which is positioned just to the left of the track when approaching the hill’s summit from the south-west.  These readings were taken from the north, west, south and east at increments of 5 metres out to 25 metres from the level, this gave us the lay of land around the summit.  A near rock proved slightly higher than our favoured natural high point, but consensus of opinion was that this was put there by man and so it was discounted from the summit measurement.

Shortly afterward the Leica GS15 was set up on the tripod and just before starting to gather data we had enough time to take a number of summit photos with the team of surveyors and SMC and TMS members gathered round.

Summit photo:  (L-R) Bill Wheeler (TMS), John Rogerson (TMS), Eleanore Hunter (TMS), Alan Brook (TMS), Rab Anderson (SMC), Andy Nisbet (SMC), Ian Collie (TMS), Graham Jackson (surveyor), David Batty (TMS), John Barnard (surveyor) and Iain Robertson (TMS)

When Alan surveyed this hill he also surveyed its connecting bealach to the adjoining Munro of Carn na Caim, the drop value from these two surveys came to 30.3m which may form a part of the deciding factor in the possible reclassification of this hill by the SMC to Munro Top status, if Alan’s measurements were confirmed with the Leica GS15, which we were sure that they would.  Therefore after the GS15 started collecting data John, Graham and me walked down to the hill’s connecting bealach to inspect the lay of its land.  In close pursuit were a number of people all heading off to bag the summit of the Munro; Carn na Caim, with Iain along with David volunteering to remain with the equipment at the summit of the south Top.

When we arrived at the bealach we were met by an unsavoury expanse of peat laden, mud splattered bog.  This we spent a number of minutes squashing around in and assessing the land and its direction from a number of positions.  The conclusion being that the critical point of the bealach probably lay in one of a number of peat runnels that crossed the bealach in a valley to valley direction.  Although I took two data sets with the Trimble, one near to where Alan had set up his Leica and one a few metres away in one of the peat runnels we decided that we should level and staff the bog once the two hours of summit data had been collected.

The first data set with the Trimble at the bealach was very close to where Alan took data from with his Leica RX1250

As the Trimble gathered its second data set John and Graham headed back to the summit and as I followed them after packing the Trimble away I met Iain as he walked down the path heading toward the summit of Carn na Caim.  I arrived back at the summit with about 30 minutes remaining of the two hour vigil and spent much of the time flat out on the ground nestled out of the breeze munching on a sandwich and chatting with Eleanore and listening to the varied conversation of the others.  All too soon it was ready to pack the equipment away and head back down to the connecting bealach.  As we did so Andy and John headed south to bag more hills, whilst David had already descended and Eleanore, Bill and Ian decided to wait for Iain to come back from the summit of Carn na Caim before heading down toward the cars.  This left John, Graham, me, Alan Brook and Rab to venture down to the delights of the bog invested bealach.

The second data set with the Trimble at the bealach was where the Leica GS15 would eventually be positioned

Alan, Graham and John heading from the summit down to the delights of the bealach

Meeting Iain on his way back from the Munro summit of Carn na Caim, which is in the background

Over the next hour we had fun in the bog laying two rows of flags, one from the hill to hill direction and the other from the valley to valley direction, we then followed one of the peaty runnels on the valley to valley direction and by doing so we pinpointed where the critical point of the bealach lay, this was where I had taken the second data set with the Trimble.

As Graham was the lightest we decided that he should venture out into the bog and operate the staff and lay the lines of flags

The next hour was spent in brightening conditions as the Leica GS15 gathered an hours’ worth of data, I then repeated the previous Trimble survey and gathered another five minutes of data.

Graham, John, Alan and Rab beside the Leica GS15 at its set-up position at the critical bealach of Mullach Coire nan Cisteachan

The third data set with the Trimble at the bealach repeated its second data set

After all the equipment had been packed away we walked back up to the summit where I gathered another five minute data set with the Trimble, and proceeded down the track in warming late afternoon sunshine to the awaiting cars below.

Gathering data with the Trimble from the summit of Mullach Coire nan Cisteachan

Descending the track after another good day on the hill

It had been a good three full days in Scotland with Tuesday’s filming by ARD with TMS members, and the unexpected bonus of surveying Creag na Caillich on Wednesday and now a two hour summit and one hour bealach data set from Mullach Coire nan Cisteachan. 

The results of these surveys will be sent to Ordnance Survey for their verification and the results forwarded to the SMC for their assessment.

Survey Result:

Mullach Coire nan Cisteachan

Summit Height:  914.6m (converted to OSGM15, Trimble GeoXH 6000) 

914.6m (converted to OSGM15, Leica RX1250) 914.6m (converted to OSGM15, 

Leica GS15) (prospective new Munro Top, now confirmed)

Summit Grid Reference:  NN 66386 80690

Bealach Height:  884.3m (converted to OSGM15 and average of two surveys, 

Trimble GeoXH 6000) 884.3 (converted to OSGM15, Leica RX1250, with 

0.07m height compensation for position) 884.2m (converted to OSGM15, Leica 


Bealach Grid Reference:  NN 66970 81301

Drop:  30.3m (Trimble GeoXH 6000, using average of two bealach surveys) 

30.3m (Leica RX1250) 30.4m (Leica GS15)

Dominance:  3.32% (based on Leica GS15 result)

For further details please consult the Trimble survey spreadsheet click {here}

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