Mapping Mountains – Hill Reclassifications – Marilyns

 

Rhinog Fach (SH 664 270) – Submarilyn reclassified to Marilyn

This is one in a series of retrospective Hill Reclassification posts that detail hills whose status has altered in the listing of the Welsh Marilyns.  These reclassification posts will give details of hills where I have had direct association with their change of status, and they will tie in with a Change Register giving detail to this list and its alterations since publication in the TACit Tables booklet. 

The listing of Welsh Marilyns was published in booklet format by TACit Tables in February 1997 and entitled The Hewitts and Marilyns of Wales.  The Marilyns were originally listed as an all British compilation and were published by Cicerone Press in 1992 in the book entitled The Relative Hills of Britain.  The list compiler for the Marilyns is Alan Dawson. 

When the Welsh Marilyns list was published in booklet format there were 156 qualifying hills with a further 27 Welsh Submarilyns also included.  The criteria for Marilyn status being any hill that has a drop of at least 150m, irrespective of their height, with the criteria for Submarilyn being any hill that has 140m or more and below 150m 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 Rhinog Fach, and it is situated in the Rhinogydd group of hills in the north-western part of Wales, and is positioned with the coast and the A496 road to its west and the A470 road to its east, and has the village of Trawsfynydd towards the north north-east and the town of Abermaw (Barmouth) towards the south south-west. 

Prior to this hill’s reclassification to Marilyn status it was listed as a Submarilyn with an estimated c 148m of drop, based on the 712m 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 564m. 

The Trimble GeoXH 6000 gathering data at the summit of Rhinog Fach

As its estimated c 148m listed drop was near the benchmark value of 150m it was prioritised for a GNSS survey and this took place on the 24^th August 2021.  The summit and bwlch of this hill were surveyed by Myrddyn Phillips using a Trimble GeoXH 6000, with two summit and three bwlch data sets taken, resulting in a 711.6m summit height and a 560.6m bwlch height, with these values giving this hill 151.0m of drop. 

The Trimble GeoXH 6000 gathering data at the bwlch of Rhinog Fach

These details were forwarded via email to the list author of the Marilyns in the evening of the 26^th August 2021, and notification received from Alan Dawson via email in the early hours of the 27^th August 2021 of his acceptance of this hill’s reclassification to Marilyn status. 

 

The full details for the hill are: 

Name:  Rhinog Fach 

OS 1:50,000 map:  124

OS 1:25,000 map:  18

Summit Height:  711.6m (converted to OSGM15) 

Summit Grid Reference:  SH 66485 27017 

Bwlch Height:  560.6m (converted to OSGM15) 

Bwlch Grid Reference:  SH 66561 26533 

Drop:  151.0m 

 

Myrddyn Phillips (November 2021)