Mapping Mountains – Hill Reclassifications – Hewitts

Calf Top (SD 664 856) – SubHewitt reclassified to Hewitt

This is one in a series of retrospective Hill Reclassification posts that detail hills whose status has altered in the listing of the English Hewitts (an acronym for Hill in England, Wales or Ireland over Two Thousand feet high).  These reclassification posts will give details of hills where I have had direct association with their change of status, and they will tie in with a forthcoming Change Register giving detail to this list and its alterations since first publication.

The listing of English Hewitts was published in booklet format by TACit Tables in June 1997 and entitled The Hewitts and Marilyns of England.  This list evolved out of The Absolute Summits of England and Wales which were known as the Sweats (an acronym for Summits in Wales and England Above Two-thousand FEET) and which was published by Cicerone Press in 1992 in the book entitled The Relative Hills of Britain.  The list compiler for the Hewitts and the preceding Sweats is Alan Dawson.

When the English Hewitts list was published in booklet format there were 178 qualifying hills listed with their criteria being any English hill at or above 2000ft (609.6m) in height with 30m minimum drop, accompanying the main list are two sub category’s entitled SubHewitts, with the two sets of criteria being any English hill at or above 600m and below 2000ft (609.6m) in height that have a minimum drop of 30m and any English hill at or above 2000ft (609.6m) in height with 20m or more and below 30m of drop.

The Hewitts and Marilyns of England by Alan Dawson

The details for the hill reclassification appear below:

The name of the hill is Calf Top, and it is situated in the Central Pennines of northern England, and is positioned with the A683 and the M6 roads to its west, and has the small town of Sedbergh towards the north and the small community of Barbon towards the south-west.

Calf Top (SD 664 856) from Castle Knott

Prior to this hill’s reclassification to Hewitt status it was listed as a SubHewitt with 312m of drop based on the 609m summit spot height that appeared on the Ordnance Survey 1:50,000 Landranger and 1:25,000 Explorer maps of the day and a col height of 297m.

As its 609m summit spot height was near the benchmark height of 2000ft (609.6m) it was prioritised for a GNSS survey and this took place on the 15th April 2010.  The hill was surveyed by John Barnard, Graham Jackson and Myrddyn Phillips using a Leica 530 and two hours of data were gathered, resulting in a summit height at that time of 609.61m.

Gathering data with the Leica 530 during the first summit survey of Calf Top

As this result was so close to the benchmark height of 2000ft (609.6m) it was decided to re-visit and gather a further four hours of data.  The second survey was conducted on the 20th May 2010 by John Barnard, Graham Jackson and Myrddyn Phillips using a Leica 530, resulting in a summit height at that time of 609.62m.  As the results from these surveys were so close to the 2000ft / 609.6m height the two data sets were sent to Ordnance Survey and were processed using their Bernese software, resulting in a summit height of 609.58m.

Gathering data with the Leica 530 during the second summit survey of Calf Top

This height was reassessed in August 2016 when Ordnance Survey adopted their new OSTN15 / OSGM15 model which replaced their OSTN02 / OSGM02 model.  The adoption of the OSTN15 / OSGM15 model increased the known height of hills in England by an average of 2cm - 4cm, and in the case of Calf Top this resulted in its known accurate height increasing to 609.61m, which is higher than the minimum 2000ft (609.6) height required for Hewitt status.

The reclassification of this hill from Sub-Hewitt to Hewitt status was accepted by the list author and its new classification augmented in to the listing of the Hewitts in August September 2016.

The full details for the hill are:

Name:  Calf Top

OS 1:50,000 map:  98

OS 1:25,000 map:  2

Summit Height:  609.61m (converted to OSGM15)

Summit Grid Reference:  SD 66450 85624

Col Height:  297m

Col Grid Reference:  SD 682 867

Drop:  313m

Myrddyn Phillips (June 2019)