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This programme shows some of the observations and reasoning that are used in building up an evolutionary history of a complex orogenic belt.
Metadata describing this Open University video programme
Module code and title: S336, Crustal and mantle processes: case studies in Earth science
Item code: S336; 10
First transmission date: 21-06-1980
Published: 1980
Rights Statement:
Restrictions on use:
Duration: 00:24:00
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Producer: Peter L Firstbrook
Contributors: Stephen Drury; Michael Johnson
Publisher: BBC Open University
Keyword(s): Collieston; Evolutionary history; Metamorphic grade; Organic belt; Scotland; Slate
Footage description: Aerial shots of a Scottish river and of an animated map of Scotland. Commentary by Michael Johnson introduces the programme by pointing out the area to be examined. Using film shots of the Banff coast and a still graphics sequence, Johnson discusses the extent and composition of the Scottish Dalradian. Steve Drury, on the shore at MacDuff, examines the rocks of the youngest part of the Dalradinn succession. He points out two important features at this location - that the slates are dipping to the West and that the fine grained rocks have the potential to form minerals which could be good indicators of metamorphic grade. Mike Johnson sums up the findings at this location. Steve Drury continues his examination of the rocks westward along the coast at Banff. He points out some low grade metamorphic minerals. Shots of some of these specimens under the polarising microscope. Commentary by Johnson identifies them as cordierite which is an important indicator of pressure and temperature at the time the rocks metamorphosed. Steve Drury looks at structural evidence which indicates that the F1 folds in the sequence must have preceded the metamorphic phase. Additional commentary by Mike Johnson. Shots of the coast at Collieston, about fifty kilometers further along the coast from Banff. Commentary by Johnson points out the F1 fault and how it differs from the Fl fault at Banff. Johnson goes on to identify the mineral Andelusite in the rocks and explains, with the aid of a graph, that pressure, temperature and depth of formation can be determined from the mineral. More shots of Steve Drury examining the coastal rocks at Collieston. He explains that he is searching for further evidence of metamorphism. Close up shots of various mineral crystals under polarised light. Commentary by Johnson explains what can be told about the timing of the metamorphism from looking at these minerals. Steve Drury points out mullions in the rock and explains how these are formed. More shots of mullions and commentary by Johnson relates these to the F2 phase of the folding sequence. He then recaps the folding and dipping of the rocks as indicated by Steve Drury. Studio graphics are used to illustrate his points. Over film shots of sea and islands as well as an animation, commentary by Mike Johnson sums up the structural history of the area. Johnson goes on, with the aid of a three dimensional diagram of a section of the Scottish Dalradian, to construct a hypothesis of what the regional structure looks like.
Master spool number: OU 3079
Production number: FOUS043X
Videofinder number: 494
Available to public: no