Great Nodden (SX 539 874) – 400m Sub-Four addition
There has been an addition to the listing of the The Fours – The 400m Hills of England, with
the summit height, col height and their locations, the drop and status of the
hill derived from detail on contemporary maps produced from Ordnance Survey
data and initiated by Joe Nuttall who produced a surface analysis programme using LIDAR with an alternative height map (DEM) allowing identification of summits and cols and thereby drops and confirmed by subsequent LIDAR analysis conducted by Myrddyn Phillips.
%20-%20LIDAR%20hill%203.jpg) |
| LIDAR image of Great Nodden (SX 539 874) |
Joe's workings area available as a spreadsheet comprising many thousands of hills and this is being evaluated by a number of people, including Ronnie Bowron, who passed the details of this hill to us for evaluation.
The criteria for the list that this addition
applies to are:
The Fours – The 400m Hills of England.
English hills at or above 400m and below 500m in height that have 30m
minimum drop, accompanying the main list are three categories
of sub hills, with this hill being added to the 400m Sub-Four category, the
criteria for which are all English hills at or above 400m and below 500m in
height that have 20m or more and below 30m of drop. The list is co-authored by Myrddyn Phillips and Aled Williams and the 2nd edition of the booklet containing this list was published by Mapping Mountains Publications on the 24th April 2018.
 |
| The Fours - The 400m Hills of England by Myrddyn Phillips and Aled Williams |
The name the hill is listed by is Great Nodden, and it is adjoined to the High
Willhays group of hills,
which are situated in Dartmoor in south-west England, and it is positioned with the A386 road to its west, and has the town
of Okehampton towards the north-east.
When the 2nd edition of the The Fours – The 400m Hills of England
was published by Mapping Mountains Publications in April 2018, this hill was
not included as it was listed with 18m of drop, based on the 437m summit spot
height that appears on the Ordnance Survey 1:50,000 Landranger and 1:25,000
Explorer maps and the 419m col spot height that used to appear on the Ordnance
Survey Vector Map Local hosted on the Geograph website and which was entitled
the Interactive Coverage Map.
%20-%201%2025000.jpg) |
| Extract from the Ordnance Survey 1:25,000 Explorer map |
These details have now been re-assessed against the mapping on the OS Maps website. This is the replacement for OS Get-a-map and until recent times had contours at 5m intervals which were proving consistently more accurate compared to the 5m contours that sometimes appear on the Ordnance Survey 1:25,000 Explorer map and used to appear on the online Vector Map Local. This mapping is digitally updated and the position of the 419m spot height has been checked against the col contours which are between 410m – 415m, and found to be on an upslope, with the height of the col estimated to be c 413m.
However, it was not until LIDAR became available that the details for this hill could be accurately re-assessed. The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales.
Therefore, the addition of this hill to 400m Sub-Four
status is due to re-assessment of detail on contemporary mapping produced from Ordnance
Survey data and confirmed by subsequent LIDAR analysis, resulting in a 436.4m summit height and a 414.1m col height, with
these values giving this hill 22.3m of drop, which is sufficient for 400m Sub-Four
status.
The full details for the hill are:
Group: High Willhays
Name: Great Nodden
OS 1:50,000 map: 191
Summit Height: 436.4m (LIDAR)
Summit Grid Reference:
SX 53918 87419 (LIDAR)
Col Height: 414.1m (LIDAR)
Col Grid Reference: SX
54229 87879 (LIDAR)
Drop: 22.3m (LIDAR)
For the additions, deletions and reclassifications to The Fours - The 400m Hills of England reported on Mapping Mountains since the December 2013 publication of the 1st edition of this list by Europeaklist please consult the following Change Registers:
Our thanks to Joe Nuttall and Ronnie Bowron for bringing the
details of this hill to our attention.
Myrddyn Phillips and Aled Williams (October 2020)
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