Mapping Mountains – Hill Reclassifications – Hewitts

Gau Graig (SH 743 140) – Hewitt reclassified to SubHewitt

This is one in a series of retrospective Hill Reclassification posts that detail hills whose status has altered in the listing of the Welsh Hewitts (an acronym for Hill in England, Wales or Ireland over Two Thousand feet high).  These reclassification posts will give details of hills where I have direct association with their change of status, and they will tie in with a forthcoming Change Register giving detail to this list and its alterations since first publication.

The listing of Welsh Hewitts was published in booklet format by TACit Tables in February 1997 and entitled The Hewitts and Marilyns of Wales.  This list evolved out of The Absolute Summits of England and Wales which were known as the Sweats (an acronym for Summits in Wales and England Above Two-thousand FEET) and which was published by Cicerone Press in 1992 in the book entitled The Relative Hills of Britain.  The list compiler for the Hewitts and the preceding Sweats is Alan Dawson.

When the Welsh Hewitts list was published in booklet format there were 137 qualifying hills listed with their criteria being any Welsh hill at or above 2000ft (609.6m) in height with 30m minimum drop, accompanying the main list are two sub category’s entitled SubHewitts, with the two sets of criteria being any Welsh hill at or above 600m and below 2000ft (609.6m) in height that have a minimum drop of 30m and any Welsh hill at or above 2000ft (609.6m) in height with 20m or more and below 30m of drop.

The Hewitts and Marilyns of Wales by Alan Dawson

The details for the hill reclassification appear below:

The name of the hill is Gau Graig, and it is adjoined to the Cadair Idris group of hills, and it is positioned with the A487 road to its south-east, and has the town of Dolgellau towards its north north-west.

Gau Graig (SH 743 140)

Prior to this hill’s reclassification to SubHewitt status it was listed as a Hewitt with an estimated c 30m of drop based on the 683m summit spot height that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and an estimated bwlch height of c 653m.

Gathering data with the Trimble GeoXH 6000 at the summit of Gau Graig

As the estimated drop value of c 30m is the minimum required for Hewitt status it was prioritised for a GNSS and line survey and this took place on the 1^st May 2015.  The hill was surveyed by John Barnard and Myrddyn Phillips using a level and staff for determining the drop of the hill and a Trimble GeoXH 6000 to determine the summit and bwlch height and also its drop value.  The survey resulted in a 683.8m summit height and a 658.4m bwlch height, with these values giving this hill 25.4m of drop, with the line survey resulting in a drop value of 25.47m.

Gathering data with the Trimble GeoXH 6000 at the critical bwlch of Gau Graig

Determining the bwlch position for Gau Graig

The reclassification of this hill from Hewitt to SubHewitt status was accepted by the list author and its new classification augmented in to the listing of the Hewitts in May 2015.

The full details for the hill are:

Name:  Gau Graig

OS 1:50,000 map:  124

OS 1:25,000 map:  23

Summit Height:  683.7m (683.8m converted to OSGM15)

Summit Grid Reference:  SH 74377 14027 (as listed in the Hewitts)

Bwlch Height:  658.3m (658.4m converted to OSGM15)

Bwlch Grid Reference:  SH 7391 1377 (as listed in the Hewitts)

Drop:  25.4m (as listed in the Hewitts with the line survey giving 25.47m drop)

Myrddyn Phillips (June 2019)