Tuesday 2 April 2019

Mapping Mountains – Trimble Surveys – Mynydd Twr


22.10.18  Sotherby Top (SH 488 836)  

Sotherby Top (SH 488 836)

This hill was the last of six I had visited during a day of generally relaxed contentment wandering the south-eastern part of Ynys Môn.  It was also a hill who’s high point may be situated in what some have described as an impenetrable blackthorn forest.

I left my car pulled in to the side of the minor road to the south of the summit, which wasn’t ideal, but the road seemed quiet and I had left my car on a relatively long straight with sufficient space for other vehicles to pass.

A boundary wall marches confidently toward the forest of blackthorn that even from distance looked unappetising.  It looked even less so as I neared its black innards.  Gorse and brambles even though unwelcome, can be bashed through, but a mass of blackthorn is another matter.  It is hard weathering and has thorns that are positively needle like and even if the high point of this hill was amongst its inner depths I was only going to dip my toe close to it, which I did from the convenience of a low point in the adjacent boundary wall.

Inside the blackthorn forest

I wanted to take two data sets, one from the high point of the land at the base of the wall and a second from another 130m ring contour to the east of my present position.  I set the Trimble up on the wall and measured a 1.20m offset between its internal antenna and the ground at its base and as part of its satellite coverage was obscured by the dense blackthorn forest I opted for ten minutes of data to be gathered and stored.

The set-up position for the first data set taken at Sotherby Top

By now I knew that my last planned walk of the day taking in the three P30s making up Mynydd Bodafon, would have to wait for another day as the sun was sinking on the western horizon giving sublime colours to the early evening.

It was only a short walk to where I wanted to take the second data set from, the high point of which was placed on a raised and elongated grassy ridge, and as the Trimble gathered its ninth and last data set of the day I watched a herd of cows slowly graze their way ever nearer to the equipment, once five minutes of data were gathered I closed the Trimble down, took a few photographs and packed it away.  Before heading back to my brother’s in Nantlle I visited the adjacent farm of Frigan where I spoke with Dawn Pritchard.

The set-up position for the second data set taken at Sotherby Top

The family of Dawn’s husband have farmed from Frigan for three generations and she told me the field leading to the boundary wall is known as Cae Pump as there is a water pump situated in it, and unprompted she then gave the name of Sotherby Top to the enclosed land where the blackthorn forest is situated.  This name had intrigued me for many years ever since first listing this hill as a P30, as an English name on an Ordnance Survey map amongst many Welsh names looks unusual, but Dawn told me that in all probability it would have been given to this part of the hill by the old estate owners at Parciau, who no doubt were English speakers.  Thanking Dawn for her time I drove south watching the sunset cast golden colour as it sank.  It had been another good day on some excellent lower heighted hills.

Sun set on my journey back to Nantlle



Survey Result:



Sotherby Top 

Summit Height:  130.4m (LIDAR)

Summit Grid Reference:  SH 48871 83632 (LIDAR)

Bwlch Height:  c 64m (interpolation)

Bwlch Grid Reference:  SH 46734 82741 (interpolation)

Drop:  c 66m (LIDAR summit and interpolated bwlch)

Dominance:  50.92% (LIDAR summit and interpolated bwlch)












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