Tuesday, 21 July 2020

The Hewitts of Ireland

Corcóg (Corcogemore) (L 952 491) – SubHewitt reclassified to Hewitt

The listing to The Hewitts and Marilyns of Ireland authored and compiled by E D ‘Clem’ Clements was published by TACit Press in September 1997.  The criteria for Irish Hewitt (an acronym for Hill in England, Wales or Ireland over Two Thousand feet high) status is any 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 Irish hill at or above 600m and below 2000ft (609.6m) in height that have a minimum drop of 30m and any Irish hill at or above 2000ft (609.6m) in height with 20m or more and below 30m of drop.

The Hewitts and Marilyns of Ireland by E D 'Clem' Clements

Since publication of this list there have been a number of status changes to it, all have been related to the qualifying drop, none until now are related to the qualifying height.

Corcóg (Corcogemore) has been surveyed by Bluesky, in 2020 Bluesky was awarded the contract by Natural Resources Wales on behalf of the Welsh Government to re-survey the whole of Wales using LIDAR capturing the data at two points per metre resolution.

For Ireland Bluesky have created a national dataset based on photogrammetric survey using Vexcel cameras, creating a 1m DSM and 5m DTM product.  The accuracy given for these is +/- 0.50m for the DSM with directly recorded points with no interpolation, and +/- 1m for the DTM with some interpolation.

Corcóg height image supplied by Bluesky

Prior to the survey conducted by Bluesky this hill was listed with a 609m summit height based on the spot height that appears on the OSI 1:50,000 Discovery map.  The relevant details for the hill appear below:

Hewitt addition:

Name:  Corcóg (Corogemore)

OSI 1:50,000:  45

Summit Height:  611.1m

Summit Grid Reference:  L 95262 49137

Col Height:  386m

Col Grid Reference:  L 943 496

Drop:  225m

Since Clem’s death the co-custodian responsibilities for the Irish Hewitts list have passed to Myrddyn Phillips and David Purchase, and both are in agreement with this hill’s change of status based on the Bluesky survey.  This reclassification also affects the list to the 500-Metre Tops of Ireland co-authored and compiled by Michael Dewey and Myrddyn Phillips, and Michael has been consulted and is also in agreement with this hill’s reclassification.
The 611m spot height for Corgóg on the new Connemara Mountains map produced by EastWest Mapping.  Photo:  Kieron Gribbon

Thanks to:

Kieron Gribbon of The Ireland Walking Guide website who raised the potential of this hill being a new Irish Hewitt based on the 611m summit spot height that appears on the Connemara Mountains map recently published by EastWest Mapping.

Barry Dalby at EastWest Mapping for confirmation of the source of their height data, and relevant details giving accurate height and co-ordinates.

Robert Loughran at Bluesky for detailed analysis of their surveying technique, including accurate heights and contours.

Myrddyn Phillips (July 2020)

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