Wednesday, 13 June 2018

Mapping Mountains – Hill Reclassifications – The Fours


Pt. 423.7m (SX 753 768) – 400m Sub-Four addition

There has been an addition to the listing of The Fours due to LIDAR analysis conducted by Aled Williams.  The Fours is the title for the list of 400m hills of England and takes in all English hills at and above 400m and below 500m in height that have a minimum 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.

Accompanying the main list of The Fours are three categories of sub hills, with this hill being added to the 400m Sub-Fours.  The criteria for 400m Sub-Four status are all English hills at and above 400m and below 500m in height that have 20m and more and below 30m of drop.
  
Prior to LIDAR analysis this hill was listed with c 18m of drop based on the 422m summit spot height that appears on the Ordnance Survey Interactive Coverage Map hosted on the Geograph website and an estimated col height of c 404m based on col contouring between 400m – 410m on the 1:50,000 Landranger and 1:25,000 Explorer maps, with the col contours between 400m – 405m on OS Maps, which is the recent replacement for OS Get-a-map.

Extract from the Ordnance Survey Interactive Coverage Map hosted on the Geograph website

As the authors do not know an individual name for this hill it appears listed under the point (Pt. 423.7m) notation, and it is situated in Dartmoor which is a part of the Cornwall and Devon region that constitutes Region 40, with its Cardinal Hill being Broad Barrow (SX 705 799).  The hill is positioned between Haytor Rocks to its east north-east and Saddle Tor to its south south-west and has the B 3387 road to its south-east and the small community of Haytor Vale towards its east north-east.

As the summit of the hill is a part of designated open access land it can be approached from a number of directions, with access from car parking beside the B 3387 road to the east and south of the hill being the most convenient way of approach.

The addition of Pt. 423.7m to 400m Sub-Four status is due to LIDAR analysis conducted by Aled Williams.  The LIDAR (Light Detection & Ranging) technique produced highly accurate height data that is now freely available for much of England and Wales.


Aled’s LIDAR analysis gives the hill the following details:

Pt. 423.7m

Summit Height:  423.7m

Summit Grid Reference:  SX 75331 76844

Col Height:  403.2m

Col Grid Reference:  SX 75484 76930

Drop:  20.5m


Therefore, the 423.7m LIDAR analysis for the summit position at SX 75331 76844 and the 403.2m LIDAR analysis for the col position at SX 75484 76930 gives this hill 20.5m of drop, which is sufficient for it to be classified as a 400m Sub-Four.


The full details for the hill are:

Cardinal Hill:  Broad Barrow

Summit Height:  423.7m (LIDAR)

Name:  Pt. 423.7m

OS 1:50,000 map:  191

Summit Grid Reference:  SX 75331 76844 (LIDAR)

Drop:  20.5m (LIDAR)


For the additions, deletions and reclassifications to The Fours reported on Mapping Mountains since the December 2013 publication of the list by Europeaklist please consult the following Change Registers:










Myrddyn Phillips and Aled Williams (June 2018)


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