Wednesday 9 December 2020

Mapping Mountains – Hill Reclassifications – The 500-Metre Tops of Ireland


Corcóg (Corcogemore) (L 952 491) – 500m Top deletion

There has been a deletion to the list of The 500-Metre Tops of Ireland, with the summit height and its location and therefore the status of the hill confirmed by a survey conducted by Bluesky.

The criteria for the list that this deletion applies to are:

The 500-Metre Tops of Ireland – Irish hills at or above 500m and below 609.6m (2000ft) in height that have 30m minimum drop.  The list is co-authored by Michael Dewey and Myrddyn Phillips and is published on Haroldstreet.

The 500-Metre Tops of Ireland by Michael Dewey and Myrddyn Phillips

The name the hill is listed by is Corcóg (Corcogemore) and it is adjoined to the Maumturk Mountains which are situated in the western part of Ireland (Region 47, Section 47C), and it is positioned with the N59 road to its south and the R336 road to its east, and has the town of Cliften towards the west.

When the original list of Irish 500m hills was compiled this hill was listed with a 609m summit height, based on the spot height that appears on the Ordnance Survey of Ireland 1:50,000 Discovery map 45.

Extract from the Ordnance Survey of Ireland 1:50,000 Discovery Series map

When the list was re-assessed for publication on the DoBIH and the Hill Bagging website this hill was listed with 223m of drop, based on the 609m summit spot height and a col height of 386m, with the latter based on the spot height that appears on the Harvey 1:30,000 Superwalker Connemara map.

Since this re-assessment Corcóg (Corcogemore) has been surveyed by Bluesky.  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.  The result produced by the Bluesky survey gives this hill a 611.1m summit height.

Bluesky generated image of the summit of Corcóg

Therefore, the deletion of this hill from the The 500-Metre Tops of Ireland list is due to a survey conducted by Bluesky, resulting in a 611.1m summit height.  As this is above the 2,000ft (609.6m) height the hill is reclassified to the The Hewitts of Ireland list.


The full details for the hill are:

Group:  Maumturk Mountains

Name:  Corcóg (Corogemore)

OSI 1:50,000 map:  45

Summit Height:  611.1m

Summit Grid Reference:  L 95262 49137

Col Height:  386m (spot height)

Col Grid Reference:  L 943 496 (spot height)

Drop:  225m



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.

Extract from the EastWest Mapping Connemara Mountains map

For the additions, reclassifications and deletions to The 500-Metre Tops of Ireland list reported on Mapping Mountains since the June 2011 publication of the list by DoBIH and the Hill Bagging website please consult the following Change Registers:










Michael Dewey and Myrddyn Phillips (December 2020)




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