Pt. 690.2m (SH 647 468)
There has been a Significant Height Revision to a hill that is listed in the The Welsh Highlands – Uchafion Cymru, with the summit height, bwlch height and their locations, the drop and status of the hill derived from a Trimble GeoXH 6000 survey conducted by Myrddyn Phillips.
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| Pt. 690.2m (SH 647 468) |
The criteria for the listing that this significant
height revision applies to are:
The Welsh Highlands – Uchafion Cymru – This is the revised draft title for the Welsh 500m P15s list that takes in all hills in Wales at or above 500m in height with 15m minimum drop. Accompanying the main list are three sub lists, these are; 500m Sub-Uchaf, 490m Sub-Uchaf and the Double Sub category. The list is co-authored by Myrddyn Phillips and Aled Williams with the Introduction to the list published on Mapping Mountains in November 2015 and an update relating to the list appearing on Mapping Mountains on the 19th June 2019.
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| The Welsh Highlands - Uchafion Cymru by Myrddyn Phillipa and Aled Williams |
The hill is being listed by the point (Pt. 690.2m) notation, and it is adjoined to the Moelwyn Mawr group of hills, which are situated in the north-western part of North Wales (Region A, Sub-Region A1), and it is positioned with the A4085 road to its south-west, the A498 road to its north-west and the A470 road to its east, and has the small community of Croesor towards the south-west and the town of Blaenau Ffestiniog towards the east.
Prior to the Trimble GeoXH 6000 survey this hill was listed with a 688m summit height, based on the spot height that appears on the Ordnance Survey Vector Map Local hosted on the Geograph website and
which is entitled the Interactive Coverage Map.
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| Extract from the Ordnance Survey Vector Map Local hosted on the Geograph website |
The summit height produced by the Trimble GeoXH
6000 survey is 690.2m, this is not a substantial height revision when compared
to some revised heights, but it does come within the parameters of the
Significant Height Revisions used within this page heading, these parameters
are:
The term Significant Height Revisions applies to any listed hill whose interpolated height and Ordnance Survey, Harvey or other interactive map summit spot height has a 2m or more discrepancy when compared to the survey result produced by the Trimble GeoXH 6000 or analysis of data produced via LIDAR. Also included are hills whose summit map data is missing an uppermost ring contour when compared with the data produced by the Trimble or by LIDAR analysis.
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| The Trimble GeoXH 6000 gathering data at the summit of Pt. 690.2m (SH 647 468) |
Therefore, the new listed summit height of this hill is
690.2m and this was derived from a Trimble GeoXH 6000 survey. This is 2.2m
higher than its previously listed height of 688m which appears as a spot height
on the Ordnance Survey Vector Map Local hosted on the Geograph website. However, this new height is in accordance with the 5m contouring on OS Maps.
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| Extract from the OS Maps website |
The full details for the hill are:
Group: Moelwyn Mawr
Name: Pt. 690.2m
OS 1:50,000 map: 115
Summit Height (New height):
690.2m (converted to OSGM15)
Summit Grid Reference:
SH 64799 46864
Bwlch Height: 670.9m
(converted to OSGM15)
Bwlch Grid Reference:
SH 64681 46742
Drop: 19.3m
Myrddyn Phillips and Aled Williams (July 2019)
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