IUGS Zumaia Declaration
← View all Geoheritage Sites

Granite landforms of Dartmoor

United Kingdom

Haytor is among the most spectacular granite tors in Dartmoor. (By Nilfanion - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=28339418).

Haytor is among the most spectacular granite tors in Dartmoor. (By Nilfanion – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=28339418).

Geological Period

Neogene to Pleistocene

Main geological interest

Geomorphology and active geological processes
Igneous and Metamorphic petrology

Location

Devon/England, United Kingdom
50°34’18”N, 003°54’55”W

Haytor is among the most spectacular granite tors in Dartmoor. (By Nilfanion – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=28339418).

Emblematic granite landforms and the global reference site for studies of granite weathering and Pleistocene cold-climate landforms.

Dartmoor is a benchmark site for studies of the evolution of granite landforms and periglaciation of uplands (Gunnell, 2020). The paper by Linton (1955), in which two-stage model of tor development was elaborated, became a major reference work in geomorphology. It inspired subsequent work on the origin of domes, inselbergs, and basins in the tropics and high latitudes. Periglacial landforms and deposits are particularly well-developed due to protracted evolution in cold environments (Eden and Green, 1971; Gerrard, 1988). Recent pioneering work using cosmogenic isotopes helped to constrain the ages of tors, opening new avenues of research (Gunnell et al., 2013).

The rolling upland surface of Dartmoor with numerous granite tors and exposed boulders.

The rolling upland surface of Dartmoor with numerous granite tors and exposed boulders.

  • Geological description

Dartmoor is a largely bare upland underlain predominantly by granite of Carboniferous age, intruded into metamorphic rocks. It is renowned for diverse rock landforms shaped by weathering and denudation (Linton, 1955; Gunnell and Jarman, 2020). The most evident and scenic are tors – castellated, tabular or dome-like outcrops of granite, some more than 20 m high, distinctively rising above smooth upland surfaces as recognizable landmarks. Diverse shapes of tors show how jointing patterns influence the evolution of landforms by controlling the progress of weathering. Many tors are products of two-stage process. A phase of deep selective weathering is followed by removal of regolith by gravity processes – a scenario later shown to be globally applicable. Dartmoor also hosts distinctive landforms inherited from the Pleistocene, including block fields and block streams, frost-riven cliffs, cryoplanation terraces, and a variety of hillslope deposits. The most elevated parts of Dartmoor may have had an ice cap in the Pleistocene. Products of granite weathering include famous kaolinite-rich mantles (China clay), which were subject to mining. There were also important tin deposits exploited since prehistoric times. The central part of Dartmoor selected as a geoheritage site represents extraordinary geodiversity, and many tors have attached cultural significance.

  • Scientific research and tradition

Various lines of geomorphological research were pursued in Dartmoor since the 19th century (Gunnell, 2020). They were focused on interrelated themes of granite weathering in changing climates, evolution of granite erosional relief, impact of cold-climate conditions on slope development, evidence of glaciation, and human-induced environmental change since antiquity.

Diversity of granite landforms and surface deposits in relation to jointing and topography, after Gunnell and Jarman (2020).

Diversity of granite landforms and surface deposits in relation to jointing and topography, after Gunnell and Jarman (2020).

  • Reference

Eden, M.J. and Green, C.P. (1971) ‘Some Aspects of Granite Weathering and Tor Formation on Dartmoor, England’, Geografiska Annaler: Series A, Physical Geography, 53(2), pp. 92–99. Available at: https://doi.org/10.1080/04353676.1971.11879838.

Gerrard, J. (1988) ‘Periglacial Modification of the Cox Tor—Staple Tors Area of Western Dartmoor, England’, Physical Geography, 9(3), pp. 280–300. Available at: https://doi.org/10.1080/02723646.1988.10642355.

Gunnell, Y. et al. (2013) ‘The granite tors of Dartmoor, Southwest England: rapid and recent emergence revealed by Late Pleistocene cosmogenic apparent exposure ages’, Quaternary Science Reviews, 61, pp. 62–76. Available at: https://doi.org/10.1016/j.quascirev.2012.11.005.

Gunnell, Y. (2020) ‘Landscape evolution of Dartmoor, SW England: A review of evidence-based controversies and their wider implications for geoscience’, Proceedings of the Geologists’ Association, 131(2), pp. 187–226. Available at: https://doi.org/10.1016/j.pgeola.2020.04.003.

Gunnell, Y. and Jarman, D. (2020) ‘Dartmoor’, in A. Goudie and P. Migoń (eds) Landscapes and Landforms of England and Wales. Cham: Springer International Publishing (World Geomorphological Landscapes), pp. 239–255. Available at: https://doi.org/10.1007/978-3-030-38957-4_13.

Linton, D.L. (1955) ‘The Problem of Tors’, The Geographical Journal, 121(4), pp. 470–487. Available at: https://doi.org/10.2307/1791756.

  • Author(s)

Piotr Migoń.
Institute of Geography and Regional Development, University of Wrocław, Wrocław, Poland.

View all Geoheritage Sites →

Contact us

IUGS Zumaia Declaration