Calf Top
{{Short description|Mountain in England}}
{{Use dmy dates|date=April 2022}}
{{Infobox mountain
| name = Calf Top
| elevation = 610 m (2000 ft)
| parent_peak = Whernside
| location = Yorkshire Dales, England
| range =
| coordinates = {{coord|54.265178|N|2.516612|W|type:mountain_scale:100000|format=dms|display=inline,title}}
| grid_ref_UK = SD 66449 85624
| topo = OS Landranger 98
| type =
| first_ascent =
| easiest_route =
| map = United Kingdom Yorkshire Dales
}}
Calf Top is a mountain in the western part of the Yorkshire Dales, England. It is located in the county of Cumbria, although Lancashire and North Yorkshire are not far away. Calf Top is a dominating profile in the view from many of the smaller hills to its west, such as Lambrigg Fell and Hutton Roof Crags.
Calf Top is separated from its neighbours, Great Coum and Aye Gill Pike by the deep trench of Barbondale, meaning that although it is lower than most of the hills in its region, it has high relative height and is a Marilyn.
Status as a mountain
The height was formerly shown on Ordnance Survey maps as 609 metres. The closeness of this figure to the threshold of {{convert|2000|ft|m|sigfig=4}} used in the United Kingdom to separate mountains and hills led to the summit being surveyed using precision GPS and levelling equipment.{{cite web |title=Survey of Calf Top |url=http://www.hill-bagging.co.uk/surveys/Survey%20of%20Calf%20Top%20(Final).doc |website=Hill Bagging |access-date=10 December 2022 |format=DOC |date=27 April 2010 |archive-date=14 April 2021 |archive-url=https://web.archive.org/web/20210414100047/http://www.hill-bagging.co.uk/surveys/Survey%20of%20Calf%20Top%20(Final).doc |url-status=live }}{{cite web |title=Second Survey of Calf Top |url=http://www.hill-bagging.co.uk/surveys/Second%20Survey%20of%20Calf%20Top%20(Final).doc |website=Hill Bagging |access-date=10 December 2022 |format=DOC |date=27 July 2010 |archive-date=14 April 2021 |archive-url=https://web.archive.org/web/20210414100333/http://www.hill-bagging.co.uk/surveys/Second%20Survey%20of%20Calf%20Top%20(Final).doc |url-status=live }} The height was found to be 609.58 ± 0.1 m, or fractionally below 2,000 feet. The result was discussed with the authors of the Nuttalls, Hewitts and Deweys who all agreed that the hill should retain its current status as a member of Dewey's list of hills at least 500 metres but less than 609.6 metres high.{{cite web |title=Is Calf Top a new 2000ft mountain? |url=http://www.hills-database.co.uk/calf_top.html |website=Hills Database |access-date=10 December 2022 |date=2016 |archive-date=7 December 2021 |archive-url=https://web.archive.org/web/20211207125006/http://hills-database.co.uk/calf_top.html |url-status=live }} Current OS maps show the height rounded to 610 metres.
The Ordnance Survey recalculated the height of the mountain in 2016 when the authoritative definition of the British national height datum, Ordnance Datum Newlyn, was transitioned from the OSGM02 geoid model to the OSGM05 version, causing a general upwards shift of 25mm in orthometric heights.{{cite web |last1=Greaves |first1=Mark |title=OSGM15 and OSTN15: Updated transformations for UK and Ireland |url=https://www.ordnancesurvey.co.uk/documents/resources/updated-transformations-uk-ireland-geoid-model.pdf |website=Ordnance Survey |access-date=9 December 2022 |format=PDF |date=2016 |archive-date=14 August 2022 |archive-url=https://web.archive.org/web/20220814184524/https://www.ordnancesurvey.co.uk/documents/resources/updated-transformations-uk-ireland-geoid-model.pdf |url-status=live }} This resulted in a height of 609.606 metres, thus updating the status of Calf Top from hill to mountain.{{cite web |title=Calf Top Cumbrian hill re-categorised as a mountain |url=https://www.bbc.co.uk/news/uk-england-cumbria-37289472 |website=BBC |access-date=9 December 2022 |date=2016 |archive-date=9 December 2022 |archive-url=https://web.archive.org/web/20221209230011/https://www.bbc.co.uk/news/uk-england-cumbria-37289472 |url-status=live }}{{cite web |title=OSGM15 - the new geoid for Britain |url=https://www.ordnancesurvey.co.uk/newsroom/blog/ostn15-new-geoid-britain |website=Ordnance Survey |access-date=10 December 2022 |date=2016 |archive-date=10 December 2022 |archive-url=https://web.archive.org/web/20221210134602/https://www.ordnancesurvey.co.uk/newsroom/blog/ostn15-new-geoid-britain |url-status=live }}
References
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{{Marilyns N Eng}}
Category:Mountains and hills of Cumbria
Category:Peaks of the Yorkshire Dales
{{Cumbria-geo-stub}}