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Ox Hill

These two mounds next to the River Swale, close to the village of Grinton, are probably glacial moraines. The eastern (left) mound has a clear embankment around it. The western mound was partially dug out to make a Royal Observer Corp monitoring station during the 'cold' war. This made a small reinforced concrete room which is now empty and sealed.

The whole site is on private land and there is no access.

The locally known name is Grinton How. How means 'hill' and there are several 'hows' in the area.

The name 'Ox Hill' appears on the 1857 OS map, but is not used locally.

A major geophysical survey of the eastern mound was carried out by Swaledale and Arkengarthdale Archaeology Group with the Archaeological Services of Durham University. The results are available here. Sections 3.1 and 3.5 quote “The mounds have been known by various names including Ox Hill, Grinton How, and Grinton Fort. The mounds appear to have been fortified but no archaeological investigations have been conducted to establish the date of these features and they have been interpreted as everything from prehistoric to medieval.”

The Brigantes Nation web-site refers to it as Grinton Fort and suggests this site may of Roman origin, though 'unknown' may be a better choice. This web-site has many photographs, a plan and details of the site.

The ADS web-site suggests it is medieval.

The Out of Oblivion website says it's probably an iron age defended hilltop enclosure. This site has a very good aerial photograph link.

English Heritage Pastscape reference linked from the ADS site says medieval has been suggested.

The 1857 OS map marks it as 'remains of a camp, supposed Roman.

This map is linked from the Pastscape site above.

The Gatehouse web-site refered to it as Ox Hill, which is the 1857 map name, and also suggests it's medieval with a motte and bailey fortification. Unfortunately this site is no longer available.


It was a Royal Observer Corp monitoring post from 1965 to 1991. It is referred to here and here.

Much information about  Royal Observer Corp monitoring posts may be found via Google - search ‘ROC monitoring post’.

Royal Observer Corp underground monitoring posts were used to record blast strengths and radiation levels in the event of a nuclear attack.