Moel y Fronllwyd 395.7m at SJ 12028 17666
Prior to this hill being included as a Submarilyn it was listed with an estimated c 139m of drop, based on the 394m summit height that appeared on the Ordnance Survey Vector Map Local hosted on the Geograph website and which was entitled the Interactive Coverage Map and an estimated c 255 bwlch height, based on interpolation of 10m contouring between 250m – 260m. Its subsequent addition to Submarilyn status is due to new Welsh LIDAR produced by Bluesky and released by the Welsh Government, resulting in a 395.7m summit height and a 254.6m bwlch height, with these values giving this hill 141.1m of drop, with its newly acquired status being confirmed by the DoBIH team on the 10.05.23. Welsh Marilyn total confirmed as 158 and Welsh Submarilyn total increases by one and confirmed as 24.
Marial Gwyn 519.6m at SH 99972 55635
This hill was listed as a Submarilyn in the The Hewitts and Marilyns of Wales booklet published by TACit Tables in 1997 with an estimated c 144m of drop, based on the 519m summit spot height adjoined to a triangulation pillar that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and an estimated c 375m bwlch height, based on interpolation of 10m contouring between 370m – 380m. Its subsequent deletion from Submarilyn status is due to a Leica RX1250 survey conducted by the list author; Alan Dawson, on the 18th October 2016 resulting in a 519.6m summit height and a 379.7m bwlch height, with these values giving this hill 139.9m of drop. The confirmation of its deletion waited until LIDAR coverage was available, and this has now been analysed independently by Aled Williams and the DoBIH team, resulting in the same drop value of 139.9m, with this confirmed via email by Alan Dawson on the 03.05.23. Welsh Marilyn total confirmed as 158 and Welsh Submarilyn total decreases by one and confirmed as 23.
Rhinog Fach 711.6m at SH 66485 27017
Rhinog Fach (SH 664 270) |
This hill was listed as a Submarilyn with an estimated c 147m of drop in the TACit Tables booklet 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 565m. The hill was subsequently surveyed by Myrddyn Phillips on the 24th August 2021 using a Trimble GeoXH 6000 resulting in a 711.6m summit height and a 560.6m bwlch height, with these values giving this hill 151.0m of drop. Alan Dawson as list author was notified of this result on the evening of the 25th August 2021 and confirmed his acceptance of its reclassification to Marilyn status in the early hours of the 26th August 2021, with a retrospective Hill Reclassification post published on Mapping Mountains. Welsh Marilyn total increases by one and confirmed as 159 and Welsh Submarilyn total decreases by one and confirmed as 24.
Mynydd Bwlch-y-Groes 441.7m at SN 86857 35625
The Trimble GeoXH 6000 gathering data at the summit of Mynydd Bwlch-y-Groes (SN 868 356) |
When the TACit Tables booklet to The Hewitts and Marilyns of Wales was published in February 1997 this hill was listed as a Submarilyn with 140m of drop, based on the 442m summit height which is adjoined to a triangulation pillar and appears as a spot height on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map, and the 302m spot height that appears on the bwlch area on the Ordnance Survey 1:25,000 Explorer map. Its subsequent deletion from Submarilyn status is due to contouring on the OS Maps website which has 5m contours at the bwlch area of this hill which are between 305m – 310m, with the position of the 302m spot height below the 305m contour line, indicating it is not positioned at the critical point of this bwlch. These details were sent to the list author; Alan Dawson, on the 8th October 2019, and notification that this hill had been deleted from Submarilyn status was received on the 16th October 2019, with a retrospective Hill Reclassification post published on Mapping Mountains. The summit of this hill was subsequently surveyed by Myrddyn Phillips and Aled Williams on the 30th December 2019 using a Trimble GeoXH 6000 resulting in a 441.7m height. Welsh Marilyn total confirmed as 158 and Welsh Submarilyn total decreases by one and confirmed as 24.
Coed y Bwnydd 201.4m at SO 36613 06919
LIDAR image of Coed y Bwnydd (SO 366 069) |
This hill was promoted to Submarilyn status due to LIDAR analysis conducted by Myrddyn Phillips. Prior to this it was listed by the name of Clytha Hill with an estimated c 68m of drop based on the 196m spot height that appears on the Ordnance Survey 1:25,000 Explorer map at SO 36831 06935 and the Ordnance Survey Vector Map local hosted on the Geograph website and which was entitled the Interactive Coverage Map at SO 36738 06931, and an estimated c 128m bwlch height, based on interpolation of contouring between 125m – 130m. The LIDAR result also affects the adjoining Trostrey Hill (SO 369 051) which has a 199m map height, with LIDAR giving Coed y Bwnydd higher and therefore the bwlch position for each hill are swapped. The swapping of each bwlch has also altered the drop value for each hill, with the caveat that the drop value for the higher hill; Coed y Bwnydd, has also been amended as there is a road cutting on the hill to hill traverse and its summit comprises an earthen embankment that forms a part of an ancient hill fort, both of which are acceptable to the list author as forming a part of the drop value. LIDAR analysis gives Coed y Bwnydd a 201.4m summit height and a 59.4m bwlch height, resulting in 142.0m of drop. These details were sent to the list author on the 3rd April 2019 and posted on the RHB forum on the 7th April 2019, and notification of the new status of this hill as a Submarilyn was received from Alan Dawson on the 9th April 2019, with a retrospective Hill Reclassification post published on Mapping Mountains. Welsh Marilyn total confirmed as 158 and Welsh Submarilyn total increases by one and confirmed as 25.
Graig Wen 555.6m at SH 73910 39474
The Trimble set-up position at the summit of Graig Wen (SH 739 394) |
Mynydd Pencarreg 414.9m at SN 57560 43215
The summit of Mynydd Pencarreg (SN 575 432) with the Trimble GeoXH 6000 gathering data |
This hill was listed in the TACit Tables booklet as a Submarilyn with an estimated c 141m of drop based on the 415m summit height that is adjoined to a triangulation pillar and which appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and an estimated bwlch height of c 274m, based on interpolation of 10m contouring between 270m – 280m. Its deletion from Submarilyn status with an estimated c 138m of drop was proposed in the Y Pedwarau booklet published in May 2013 by Europeaklist and authored by Myrddyn Phillips and Aled Williams. Its eventual deletion from Submarilyn status with a revised drop of c 139m was instigated by the DoBIH team and agreed by the list author in August 2013. The bwlch height of this hill was subsequently ascertained by LIDAR analysis initially conducted by Aled Williams and subsequently by Myrddy Phillips, and its summit later surveyed by Myrddyn Phillips on the 31st July 2018 using a Trimble GeoXH 6000, resulting in a 414.9m summit height and a 276.7m bwlch height, with these values giving this hill 138.2m of drop and confirming its deletion from Submarilyn status. Welsh Marilyn total confirmed as 158 and Welsh Submarilyn total decreases by one and confirmed as 23.
Middleton Hill 205.1m at SN 14646 11773
The summit of Middleton Hill (SN 146 117) |
Mynydd Anelog 191.4m at SH 15193 27218
The Leica GS15 gathering data at the summit of Mynydd Anelog (SH 151 272) |
Mynydd y Cwm 304.9m at SJ 07307 76734
Gathering data during the second summit survey of Mynydd y Cwm (SJ 073 767) |
Moelfre 335.3m at SN 32616 36119 & SN 32619 36117
LIDAR image of Moelfre (SN 326 361) |
This hill was originally listed in the TACit Tables booklet as a Submarilyn with 143m of drop, based on the 335m summit spot height that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer map and a 192m bwlch height. By July 1997 Alan Dawson had deleted this hill from Submarilyn status as the bwlch position that gave this hill a listed drop of 143m was incorrect. Subsequent LIDAR analysis conducted by Myrddyn Phillips gives a 335.3m summit height and a 231.0m bwlch height, with these values giving this hill 104.4m of drop. Welsh Marilyn total confirmed as 156 and Welsh Submarilyn total decreases by one and confirmed as 26.
1997 (February) – TACit Tables publishes The Hewitts and Marilyns of Wales.
No comments:
Post a Comment