Thursday, 27 April 2017

Mapping Mountains – Hill Reclassifications – The Fours

Reilth Top (SO 284 881) - Four reclassified to 400m Sub-Four

There has been a reclassification to the listing of The Fours with a Four being reclassified to the ranks of 400m Sub-Four due to a survey with the Trimble GeoXH 6000.  The 400m Sub-Fours is one of three categories of sub hills that accompany the main The Fours list, with the criteria for Four status being all English hills at or above 400m and below 500m in height with 30m minimum drop, and the criteria for 400m Sub-Four status being all English hills at or above 400m and below 500m in height with 20m or more and below 30m of drop.

The hill is situated in the Beacon Hill group with its Cardinal Hill being Cilfaesty (SO 128 840) and is placed in Region 38, Section 38A Shropshire, and is positioned with the town of Bishop’s Castle towards its east.

The hill can be ascended from its south south-west or south-east where public footpaths give access to its lower slopes; however its summit is not a part of open access land so permission to visit should be sought.

The name of the hill is Reilth Top and prior to the survey with the Trimble GeoXH 6000 and its subsequent listing as a 400m Sub-Four it was listed as a Four with c 30m of drop based on an estimated summit height of c 406m with its uppermost summit contour on Ordnance Survey 1:25,000 Explorer maps being 405m, and an estimated col height of c 376m with col contouring between 375m – 380m.

The survey with the Trimble produced a summit height of 404.6m (converted to OSGM15) and a col height of 375.6m (converted to OSGM15), with these values giving this hill 29.0m of drop, which is insufficient for it to retain its Four status.

The full details for the hill produced by the Trimble are:

Cardinal Hill:  Cilfaesty

Summit Height:  404.6m (converted to OSGM15)

Name:  Reilth Top

OS 1:50,000 map:  137

Summit Grid Reference:  SO 28458 88105

Drop:  29.0m (converted to OSGM15)

Upon receiving the above details for confirmation of this hill’s reclassification Aled analysed LIDAR data and the details produced by the Trimble and LIDAR are given below:

Summit Height: 

404.6m (converted to OSGM15) at SO 28458 88105 for Trimble

404.6m at SO 28456 88108 for LIDAR

Col Height: 

375.6m (converted to OSGM15) at SO 28861 87869 for Trimble

375.3m at SO 28880 87845 for LIDAR


29.0m for Trimble

29.3m for LIDAR

The col position and height being used is that produced by LIDAR data.

The overall total for The Fours is now 294 hills with two reclassifications, one each to 390m Sub-Four and 400m Sub-Four status since publication of the list by Europeaklist in December 2013.

The overall total for the 400m Sub-Fours is now 155 with this reclassification being to first addition to this sub category since publication of the list by Europeaklist in December 2013.

The list of Four hills is available from the Haroldstreet website (January 2014) with all subsequent changes detailed on the Mapping Mountains site.

For the additions 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:

Gathering data at the summit of Reilth Top - now reclassified from a Four to a 400m Sub-Four

Myrddyn Phillips and Aled Williams (April 2017)

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