Stirling Sill

Stirling Sill

The Stirling Sill is the outcropping of a large quartz-dolerite intrusion or sill similar to those which underly a large part of central Scotland, and may be contiguous at great depth. The sill is of very late carboniferous age or more probably permian, as it penetrates the coal measures, often in bedding planes between the various strata, but in places it rises through fractures in the strata to a new level, forming features which, were they to be at the surface, would be called dykes.

At its outcrop on the west, the sill generally lies towards the base of the carboniferous sequence, and just above the calciferous sandstone deposits and lavas, as can be seen in the upper part of the valley of the Bannock Burn. However, to the consternation of miners, it occupies a higher position amongst the useful strate towards the east, and in places has destroyed the coal, while in others the effect of the sill has been to convert the coal to more valuable anthracite.

The slope of the Abbey Craig, or the Stirling Castle rock, gives a general idea of the angle of dip of the coal measures at the extremity or the coalfield, and the thickness of the sill can also be seen, which is in the region of 100 metres.

Some geologists have had various theories about the formation of anthracite, as the coal has been most effectively baked near the Ochil Fault, however the theories are not necessarily incompatible.

The source of the sill, where the molten rock rose from below, is not known, however it is known that there are risers in the Ochil Fault, although these are inconsistent with the overall structure. The main origin of the sill may be in the region of the eruptive centre which formed the Ochil Hills in a much earlier period, which is postulated to be somewhere to the east of Stirling, possibly in the region of Kincardine. This would tie in with subsidence following the first round of eruptive activity leading to the formation of the coal basins, with a much later outbreak of intrusive activity from the same magma feeders, however the truth will remain unknown because it would take very many deep bores in hard rock to probe the depths and find the necessary evidence.

The western extremities of the sill can be seen at the Abbey Craig, Stirling Castle, Kings Park, Gillies Hill, Sauchieburn and various points to the south. The quartz-dolerite was once quarried at several places including Cambusbarron and Murrayshall, but is quarried today at Northfield, primarily for roadstone.


Wikimedia Foundation. 2010.

Игры ⚽ Поможем решить контрольную работу

Look at other dictionaries:

  • Stirling Castle — Stirling, Scotland GB grid reference NS789940 …   Wikipedia

  • Stirling — infobox UK place country = Scotland official name= Stirling gaelic name= Sruighlea scots name= Stirlin population= 41,243 (2001 Census) os grid reference= NS795935 unitary scotland= Stirling lieutenancy scotland= Stirling and Falkirk constituency …   Wikipedia

  • Bannock Burn — The Bannock Burn is a stream ( burn is Scots for stream) which rises in the Touch Hills to the south west of Stirling in central Scotland. The Bannock flows eastward and enters the River Forth to the east of Stirling, close to the site of the… …   Wikipedia

  • Abbey Craig — Infobox Mountain Name = Abbey Craig Photo = Wfm wallace monument.jpg Caption = Wallace Monument on the summit of Abbey Craig Elevation = 111 m (364 ft) Location = Ochil Hills, Scotland Range = Prominence = Coordinates = Topographic OS Landranger… …   Wikipedia

  • Mercedes-Benz 300 SLR — Stirling Moss drives his Mercedes Benz 300 SLR at the Nürburgring in 1977 The Mercedes Benz 300 SLR (W196S) was a sportscar racing car for the 1955 World Sportscar Championship season, which it won. Contents …   Wikipedia

  • Order of battle of the Battle of Long Island — Lord Stirling leading an attack against the British in order to enable the retreat of other troops at the Battle of Long Island, 1776. Painting by Alonzo Chappel, 1858. The …   Wikipedia

  • Liste der Biografien/Sil — Biografien: A B C D E F G H I J K L M N O P Q …   Deutsch Wikipedia

  • Geologie des Death Valley — Luftaufnahme des Death und Panamint Valley (NASA). Die elliptische Vertiefung links ist das Becken des Searles Lake, das kleinere Längstal ist Panamint Valley, das größere ist Death Valley. Der Gebirgszug dazwischen ist die Panamint Range, und… …   Deutsch Wikipedia

  • List of people from Michigan — A list of notable people from the U.S. state of Michigan. Bolding indicates places in Michigan. People from Michigan are sometimes referred to as Michiganders, Michiganians, or more rarely as Michiganites. Actors, entertainers and… …   Wikipedia

  • McLaren Automotive — Type Private Industry Automotive Founded 1989 …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”