Editing Dartmoor (section)

==Physical geography==
===Geology===
[[File:Cornubian batholith.png|thumb|upright=1.8|Map showing the main granite outcrops of the [[Cornubian batholith]] in southwest England and the gravity anomaly associated with it]]

{{Main|Geology of Dartmoor National Park}}
Dartmoor includes the largest area of [[granite]] in Britain, with about {{convert|625|km2|mi2|abbr=on}} at the surface, though most of it is under superficial [[peat]] deposits. The granite (or more specifically [[adamellite]]) was intruded at depth as a [[pluton]] into the surrounding sedimentary rocks during the [[Carboniferous]] period, probably about 309 million years ago.<ref>Durrance & Laming 1982, pp.86, 101</ref> It is generally accepted that the present surface is not far below the original top of the pluton; evidence for this includes partly digested [[shale]] [[xenolith]]s, contamination of the granite and the existence of two patches of altered [[sedimentary rock]] on top of the granite.<ref>Durrance & Laming 1982, p. 88</ref>
A considerable [[gravity anomaly]] is associated with the Dartmoor pluton as with [[gravity anomalies of Britain and Ireland|other such plutons]].<ref>British Geological Survey 1997, ''Gravity Anomaly Map of Britain, Ireland and Adjacent Areas'', Smith & Edwards 1:500k</ref> Measurement of the anomaly has helped to determine the likely shape and extent of the rock mass at depth.

===Tors===
[[File:Saddle tor to Hey tor pano.jpg|thumb|left|Panorama of some better known Dartmoor [[Tor (rock formation)|tors]] in snow]]
[[File:High Willhays.jpg|thumb|left|[[High Willhays]] with Yes Tor behind]]

Dartmoor is known for its [[Tor (rock formation)|tor]]s – hills topped with outcrops of bedrock, which in [[granite]] country such as this are usually rounded boulder-like formations. More than 160 of the hills of Dartmoor have the word ''tor'' in their name but quite a number do not.<ref name="DF"/> However, this does not appear to relate to whether or not there is an outcrop of rock on their summit. The tors are the focus of an annual event known as the [[Ten Tors Challenge]], when around 2,400 people aged between 14 and 19 walk for distances of 56, 72 or 88&nbsp;km (35, 45 or 55&nbsp;mi) between ten tors on many differing routes.

The highest points on Dartmoor are on the northern moor: [[High Willhays]], {{convert|621|m|ft|abbr=on}}, ({{gbmapping|SX 580892}}) and [[Yes Tor]], {{convert|619|m|ft|abbr=on}}, ({{gbmapping|SX 581901}}). The highest points on the southern moor are [[Ryder's Hill]], {{convert|515|m|ft|abbr=on}}, ({{gbmapping|SX 660690}}), Snowdon {{convert|495|m|ft|abbr=on}}, ({{gbmapping|SX 668684}}), and an unnamed point, {{convert|493|m|ft|abbr=on}} at ({{gbmapping|SX 603645}}), between Langcombe Hill and Shell Top. The best-known tor on Dartmoor is [[Haytor]]<ref>{{cite book|last1=Bradt|first1=Hilary|last2=Booth|first2=Janice|title=South Devon & Dartmoor|date=2014|publisher=Bradt|location=Chalfont St Peter|isbn=9781841625522|page=222}}</ref> (called Hey Tor by William Crossing), {{convert|457|m|ft|abbr=on}}, ({{gbmapping|SX 757771}}). For a more complete list see [[List of Dartmoor tors and hills]].

===Rivers===
[[File:ErmeIvybridge.jpg|thumb|left|[[River Erme]] at [[Ivybridge]]]]

The high ground of Dartmoor forms the [[drainage basin|catchment area]] for many of Devon's rivers. As well as shaping the landscape, these have traditionally provided a source of power for moor industries such as [[Dartmoor tin-mining|tin mining]] and quarrying.

The moor takes its name from the [[River Dart]], which starts as the [[East Dart River|East Dart]] and [[West Dart River|West Dart]] and then becomes a single river at [[Dartmeet]]. It leaves the moor at [[Buckfastleigh]], flowing through [[Totnes]] below where it opens up into a long [[ria]], reaching the sea at [[Dartmouth, Devon|Dartmouth]]. Other rivers flowing from Dartmoor include the [[River Teign|Teign]], the [[River Taw|Taw]], the [[River Tavy|Tavy]], the [[River Avon, Devon|Avon]], and the [[River Lyd, Devon|Lyd]].

Some of the rivers in Dartmoor have been dammed to create [[Dartmoor reservoirs|reservoirs for drinking water]], including the River Avon<ref>{{Cite web |title=Avon Dam, Devon|url=https://www.swlakestrust.org.uk/avon-dam |access-date=22 April 2022 |website=South West Lakes Trust|date=20 December 2018 }}</ref> and the South Teign River (Fernworthy Reservoir).<ref>{{cite web|url=http://teign-catchment.co.uk/from-source-to-chagford/|title=Source Area|last=Gearing|first=David|work=The Teign Catchment|access-date=24 April 2022}}</ref>

===Bogs===
Much more rain falls on Dartmoor than in the surrounding lowlands. As much of the national park is covered in thick layers of [[peat]] (decaying vegetation), the rain is usually absorbed quickly and distributed slowly, so the moor is rarely dry. In areas where water accumulates, dangerous [[bog]]s or mires can result. Some of these, topped with bright green moss, are known to locals as "feather beds" or "quakers", because they can shift (or 'quake') beneath a person's feet. Quakers result from sphagnum moss growing over the water that accumulates in the hollows in the granite.<ref>{{cite book|first=Ian |last=Mercer |chapter=Bogs and Mires of Dartmoor |editor-last1=Hunt |editor-first1=P. J. |editor-last2=Wills |editor-first2=G. L. |date=1977 |title=Devon Wetlands |location=Exeter |publisher=Devon County Council |page=16 |isbn=0-903849-19-4}}</ref><ref>{{cite web
|url=http://www.legendarydartmoor.co.uk/bogs_moor.htm
|title=The Bogs & Mires of Dartmoor
|publisher=Legendary Dartmoor
|access-date=12 July 2009
|last=Sandles
|first=Tim
|archive-date=1 November 2020
|archive-url=https://web.archive.org/web/20201101133944/https://www.legendarydartmoor.co.uk/bogs_moor.htm
|url-status=dead
}}</ref><ref>{{cite book |last=Crossing |first=W. |title=Crossing's Guide to Dartmoor |date=1912 |publisher=Western Morning News Co. Ltd.}}</ref>

[[File:Aune head mire3.jpg|thumb|left|[[Aune Mire]], the source of the [[River Avon, Devon|River Avon]]]]
The vegetation of the bogs depends on the type and location. [[Blanket bog]], which forms on the highest land where the rainfall exceeds {{convert|2000|mm|in}} a year, consists mainly of cotton-grass (''[[Eriophorum]]'' species), sedges (''[[Carex]]'' and ''[[Rhynchospora]]''), ''[[Narthecium ossifragum|Bog Asphodel]]'' and ''[[Common Tormentil]]'', with ''[[Sphagnum]]'' thriving in the wettest patches. The valley bogs have lush growth of [[Juncaceae|rushes]], with sphagnum, [[Erica tetralix|cross-leaved heath]], [[Drosera|sundews]] and several other species.<ref>{{cite book
| last=Brunsden
| first=Denys
| author2=Gerrard, John
| editor=Crispin Gill
| title=Dartmoor. A New Study
| chapter=The Physical Environment of Dartmoor
| publisher=David and Charles
| year=1970
| location=Newton Abbot
| pages=[https://archive.org/details/dartmoornewstudy0000gill/page/40 40–42]
| isbn=0-7153-5041-2
| chapter-url-access=registration
| chapter-url=https://archive.org/details/dartmoornewstudy0000gill/page/40
}}</ref>

Some of the bogs on Dartmoor have achieved notoriety. [[Fox Tor|Fox Tor Mires]] was supposedly the inspiration for Great Grimpen Mire in Conan Doyle's novel ''[[The Hound of the Baskervilles]]'',<ref>{{cite web
|url=http://www.legendarydartmoor.co.uk/grim_mire.htm
|title=Dartmoor's Notorious Fox Tor Mires
|publisher=Legendary Dartmoor
|access-date=7 July 2009
|last=Sandles
|first=Tim
|archive-date=23 March 2009
|archive-url=https://web.archive.org/web/20090323024547/http://legendarydartmoor.co.uk/grim_mire.htm
|url-status=dead
}}</ref> although there is a waymarked footpath across it. [[Sabine Baring-Gould]], in his ''Book of Dartmoor'' (1900) related the story of a man who was making his way through Aune Mire at the head of the [[River Avon, Devon|River Avon]] when he came upon a top-hat brim down on the surface of the mire. He kicked it, whereupon a voice called out: "What be you a-doin' to my 'at?" The man replied, "Be there now a chap under'n?" "Ees, I reckon," was the reply, "and a hoss under me likewise."

<ref>Milton 2006, p. 2</ref><!-- mention "Dartmoor Stables" -->

===Astronomy===
[[File:Aurora Borealis visible over Dartmoor 02.jpg|alt=A picture of the sky with red at the top, which fades to green at the bottom, with some streaking grey vertical lines.|thumb|upright|[[Aurora borealis]] visible from near [[Bridford]] during the [[May 2024 solar storms]]]]
Dartmoor is popular with local astronomers because it is remote from many sources of [[light pollution]]. However, in recent years, [[Light-emitting diode|LED]] [[street light]]s have caused more light pollution to be spread onto Dartmoor.<ref>{{Cite web |last=Sidgreaves |first=Martin |date=2020-07-24 |title=Under a Dartmoor Night Sky |url=https://dartmoorwalker.co.uk/2020/07/under-a-dartmoor-night-sky/ |access-date=2024-05-10 |website=Dartmoor Walker |language=en-GB}}</ref>