Mam Tor, July 2011
|Elevation||517 m (1,696 ft)|
|Prominence||62 m (203 ft)|
|Location||Peak District, England|
OS Explorer OL1OS Landranger 110
Mam Tor is a 517 m (1,696 ft) hill near Castleton in the High Peak of Derbyshire, England. Its name means "mother hill", so called because frequent landslips on its eastern face have resulted in a multitude of 'mini-hills' beneath it. These landslips, which are caused by unstable lower layers of shale, also give the hill its alternative name of Shivering Mountain. In 1979 the continual battle to maintain the A625 road (Sheffield to Chapel en le Frith) on the crumbling eastern side of the hill was lost when the road officially closed as a through-route.
Mam Tor is near the top of Winnats Pass (a steep and narrow limestone gorge) and forms the eastern end of Rushup Edge. It also dominates the western end of the Great Ridge, which separates the Hope Valley to the south from Edale to the north, and is a popular ridgewalk.
Mam Tor is made of rocks of Carboniferous age, approximately 320 million years old. The base of Mam Tor is composed of black shales of the Bowland Shale Formation of Serpukhovian age overlain by tubiditic sandstone of the Mam Tor Sandstone Formation of Bashkirian age.
Mam Tor landslide 
One of the distinguishing features of Mam Tor Peak is the active debris flow resulting from a rotational landslide that occurred roughly 4,000 years ago. The initial failure exposed bedrock displaying a sequence of shales and sandstones near to the summit. Evidence for the continued movement of the slide mass is demonstrated graphically by the continued severe damage to the old Mam Tor road that traversed this flow. The road was originally built at the beginning of the 1800s and was subsequently relaid until local authorities closed the road in 1979. Layers of tarmac and gravel are up to 2 metres (6 ft 7 in) thick in places, demonstrating the numerous efforts to keep the road open.
Current mean annual movement according to a study made in 2000 is "up to 0.25 m; this increases greatly when winter rainfalls exceed thresholds of both 210 mm/month and 750 mm in the preceding six months."
The debris flow poses no threat to any inhabited buildings near the peak; however, small farm buildings lying in the flow's path may become inundated over the next century assuming a flow rate similar to that of the present. The 2000 study suggests that deep drainage may be the most effective means of stabilising the flow, though this may not completely stop movement.
The summit of Mam Tor is encircled by a late Bronze Age and early Iron Age hill fort. Radiocarbon analysis suggests occupation from around 1200 BC. The earliest remaining features are two Bronze Age burial mounds, one just below the summit and the other on the summit itself. At a later stage over a hundred small platforms were levelled into the hill near the summit, allowing inhabited timber huts to be constructed.
See also 
- Breast shaped hill
- List of hill forts in England
- Pennine Way
- Moel Famau (Welsh for "Mother Mountain")
- "Mam Tor". National Trust. Retrieved 9 January 2013.
- Natural Curiosities of Derbyshire, in: The Every-day Book and Table Book; or, Everlasting Calendar of Popular Amusements, Sports, Pastimes, Ceremonies, Manners, Customs, and Events, Each of the Three Hundred and Sixty-Five Days, in Past and Present Times; Forming a Complete History of the Year, Months, and Seasons, and a Perpetual Key to the Almanac, Including Accounts of the Weather, Rules for Health and Conduct, Remarkable and Important Anecdotes, Facts, and Notices, in Chronology, Antiquities, Topography, Biography, Natural History, Art, Science, and General Literature; Derived from the Most Authentic Sources, and Valuable Original Communication, with Poetical Elucidations, for Daily Use and Diversion. Vol III., ed. William Hone, (London: 1838) p 11–16. Retrieved on 24 June 2008.
- Waters, C. N. and Davies S. J. (2006) Carboniferous: extensional basins, advancing deltas and coal swamps - Chapter 9 of Brenchley, P. J. and Rawson P. F. (editors) (2006) The Geology of England and Wales, 2nd edition, London, The Geological Society
- Waltham & Dixon (2000), Movement of the Mam Tor landslide, Derbyshire, UK, The Quarterly Journal of Engineering Geology and Hydrogeology, Volume 33, Number 2, May 2000, pp. 105–123(19)
View from Mam Tor looking north towards the Vale of Edale
Further reading 
- Coombs, D. G.; Thompson, F.H. (1979), "Excavation of the hillfort of Mam Tor, Derbyshire", Derbyshire Archaeological Journal 99: 7–51
- Mam Tor Landslide British Geological Survey