Mapping Mountains – Trimble Surveys – Moel Hebog

22.02.14  Pen yr Allt (SH 567 418), Y Fedw (SH 557 413) and Foel yr Erw (SH 560 418)

Foel yr Erw (SH 560 418)

Another excellent day in the company of Aled investigating two 200m hills and a prospective new 300m P30 above Prenteg near to Tremadog, we met in Porthmadog and drove to a pull in spot (SH 565 419) on the high, narrow lane that joins Prenteg with Cwm Ystradllyn.

Above us rose Pen yr Allt (SH 567 418) with a rather steep profile when viewed from the lane, we slowly made our way up beside a delicate rocky rib, as height was gained we could see down towards Llyn Du (SH 562 424) an expanse of water with moorland protecting its outer limits.  Across the narrow lane was our last objective; Foel yr Erw.

Llyn Du (SH 562 424) with Crib Nantlle in the background

Aled had suggested these hills as he wondered if Pen yr Allt would make P30 status and as Y Bengam and Foel yr Erw have no spot height on current maps we could at least attain an absolute height for each with the Trimble and also determine which of the two is higher as each has an uppermost c 280m ring contour.

The summit area of Pen yr Allt has four c 340m contours with a fifth a little farther to the north on the Ordnance Survey 1:25,000 map.  As we approached the top the wind increased in strength, but with the sun out it felt pleasant.  However, the forecast was for rain to push inland from the west of Wales during the afternoon.

The high point of Pen yr Allt is a large boulder with the remains of an untidy cairn on it.  We looked out on the land where each of the other c 340m contours lay, all were lower.  The Trimble was set up on the very highest point and wedged in place with small rocks.  During the 17 minutes of data collection we retired behind a rock out of the wind and had a good chat.

The Trimble GeoXH 6000 on the high point of Pen yr Allt (SH 567 418)

Aled at the summit of Pen yr Allt

Once the Trimble was put back in its bag Aled led the way toward the connecting bwlch where we gathered 18 minutes of data.  The bwlch is positioned near to a stone wall with the land beyond continuing up to Moel Ddu (SH 579 442).  A few minutes later and we were back at the car driving further down the lane where we parked close to Ty-newydd, no longer an apt name as it was in a state of disrepair.

The Trimble at the bwlch of Pen yr Allt

By now the sky had lost its blue and banks of grey were rolling in from the sea.  All higher peaks were now cloaked under the cloud and it seemed as if the predicted rain was going to overtake us before we had finished the walk.

From Ty-newydd a footpath led us in to a bog, which we did our best to avoid.  The second hill of the day; Y Fedw is a little gem with two or three false tops leading up to a marvellous viewpoint.  Even with the higher peaks under cloud the view was excellent, looking out over Porthmadog and the Traeth Mawr with the Cambrian coast sweeping southward.  Out to the west was the expanse of grey sea and away to the north were the imagined peaks of Moel Hebog and Crib Nantlle.

Looking toward the summit of Y Fedw (SH 557 413)

The Trimble was set up on a large erratic that Aled did his best to move, we again wedged small rocks either side of it to stop the wind taking it air borne.  Aled lay next to it just in case quick reflexes were needed to save it from being deposited in the Irish Sea.

Any sign that the Trimble was going to end up airborne and Aled was going to grab it!

From here we scrambled over another high stone wall making sure that no rocks were disturbed, this led us to the bwlch between Y Fedw and Foel yr Erw and another data set was gathered with the Trimble.

At the bwlch between Y Fedw and Foel yr Erw

The next part of the walk was on a good little ridge leading toward the rocky summit of Foel yr Erw.  By now the wind was quite strong; I looked for any loose small rocks that could be wedged beside the Trimble to protect it from being blown off the highest rock.  None were found, but thankfully it found a position securely wedged in place without the aid of any rock and remained in place even with the wind doing its utmost to dislodge it.

Foel yr Erw (SH 560 418)

The Trimble GeoXH 6000 gathering data at the high point of Foel yr Erw

We debated what way to head off the hill; the most direct was through what looked like a large bog, whist the easiest was over fields to the narrow lane.  The latter option was not ideal as two vehicles were parked at the point where we’d be aiming for.  The two vehicles had three sheep gatherers beside them.  Aled quickly looked at the map and suggested a footpath that led down to a house at SH 561 415.  By the time we’d walked there two of the sheep gatherers had arrived and were unloading feed for a number of sheep.

Fifteen minutes later we walked away with a mound of local place-names, with confirmation that our first hill of the day is known locally as Pen yr Allt (a name that appears on the OS enlarged Geograph map south-eastward of the summit) and the third hill we visited is known as Foel yr Erw, which is the name that appears on the map.  Ffridd names were given as well as alternate names and even a high cwm name in the Carneddau (one of the gatherers used to work on the hills of the Carneddau).  We then gathered a data set from the bwlch for Foel yr Erw and with all three hills having their name confirmed and with each also having their summit and adjoining bwlch Trimbled, we walked down the lane to the car very happy, and even the rain kept off.  Great!

Survey Result:

Pen yr Allt

Summit Height:  344.6m (converted to OSGM15)

Summit Grid Reference:  SH 56773 41894

Bwlch Height:  317.4m (converted to OSGM15)

Bwlch Grid Reference:  SH 56774 42418

Drop:  27.2m (Sub-Trichant status confirmed)

Dominance:  7.89%

Y Fedw

Summit Height:  280.1m (converted to OSGM15)

Summit Grid Reference:  SH 55732 41332

Bwlch Height:  243.7m (converted to OSGM15)

Bwlch Grid Reference:  SH 55841 41402

Drop:  36.4m

Dominance:  12.99%

Foel yr Erw

Summit Height:  280.2m (converted to OSGM15)

Summit Grid Reference:  SH 56036 41878

Bwlch Height:  236.4m (converted to OSGM15)

Bwlch Grid Reference:  SH 56510 41829

Drop:  43.8m

Dominance:  15.62%

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