Tan y Bryn (SH 321 733)
There has been a Significant Name Change to a hill
that is listed in the Double Sub-Twmpau adjoined to the 30-99m Twmpau, with the summit height, bwlch height and their
locations, the drop and status of the hill derived from LIDAR analysis
conducted by Myrddyn Phillips.
LIDAR image of Tan y Bryn (SH 321 733) |
30-99m Twmpau - Welsh hills at or above 30m and below 100m in height with 30m minimum
drop, this height band of hills has two accompanying sub lists, the first of
which is entitled the 30-99m Sub-Twmpau with the criteria for this sub category
being all Welsh hills at or above 30m and below 100m in height with 20m or more
and below 30m of drop, and the second sub category is entitled the Double
Sub-Twmpau with the criteria for this sub category being all Welsh hills at or
above 20m and below 30m in height with 20m or more and below 30m of drop, with
the word Twmpau being an acronym standing for thirty welsh metre prominences and upward.
The 30-99m Twmpau by Myrddyn Phillips |
When the original 30-99m height band of Welsh P30 hills were published on Geoff Crowder’s v-g.me website this hill was not included in the Hills to be surveyed sub list, as it was considered not to meet the criteria then used for this sub category.
After the sub list was standardised, and interpolated heights and drop values also included the details for this hill were re-evaluated and it was listed under the point (Pt. 24m) notation with an estimated c 20m of drop, based on the 24m summit spot 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 4m bwlch height based on interpolation of 5m contouring between 0m – 5m that appear on the Ordnance Survey 1:25,000 Explorer map.
Extract from the Ordnance Survey 1:25,000 Explorer map |
Extract from the Tithe map |
Extract from the apportionments |
The full details for the hill are:
Group: Ynys Môn
Name: Tan y Bryn
Previously Listed Name: Pt. 24m
OS 1:50,000 map: 114
Summit Height: 25.1m
(LIDAR)
Summit Grid Reference:
SH 32145 73399 (LIDAR)
Bwlch Height: 3.8m
(LIDAR)
Bwlch Grid Reference:
SH 32945 73411 (LIDAR)
Drop: 21.3m (LIDAR)
Myrddyn Phillips (August 2021)
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