Available online
Description
This programme looks at the geophysical evidence which indicates a granite underlying the limestones of the Askrigg Block in the Yorkshire Dales.
This programme looks at the geophysical evidence which indicates a granite underlying the limestones of the Askrigg Block in the Yorkshire Dales.
| Module code and title: | S335, Surface and sedimentary processes: case studies in Earth sciences |
|---|---|
| Item code: | S335; 03 |
| First transmission date: | 23-02-1980 |
| Published: | 1980 |
| Rights Statement: | |
| Restrictions on use: | |
| Duration: | 00:25:00 |
| + Show more... | |
| Producer: | P. L Firstbrook |
| Contributors: | Geoff Brown; Dennis Jackson; Mick Lee |
| Publisher: | BBC Open University |
| Keyword(s): | Askrigg block; Bouguer anomaly; Gravity meter; Limestone; Magnetometer; Sedimentary basin; Wensleydale granite |
| Footage description: | Dennis Jackson, on the Askrigg Block, introduces the programme. He points out some interesting features of the overlying limestones. Jackson postulates a deep seated granite beneath the overlying limestone to account for the rigidity of the Pennines over the past 200 million years. He briefly discusses the geological evidence to support this. Shots of an I.G.S. team making a gravity survey of the Askrigg Block. Commentary by a team member, Mick Lee, explains how gravity surveys are carried out and interpreted. Animated diagrams help to illusttrate his points. Shots of an aerial magnetic survey being carried out by helicopter. Shots of equipment used for ground magnetic surveys. Commentary by Mick Lee. An animated diagram illustrates how the instrument used in such surveys, a proton procession magnetometer works. Shots of a ground magnetic survey in progress. George Brown explains how data from a magnetic survey is analysed. He points to a magnetic contour map of the Askrigg Block as he talks. Next, using a two dimensional cross section of the map, Brown interprets the magnetic data. He explains the principles behind his analysis as he goes along. George Brown goes on to explain why the geophysical evidence (gravitational and magnetic) points to a buried granite beneath the Askrigg Block. He shows a magnetic anomaly map of Britain as well as a gravity anomaly map of the Askrigg area and the Northern Pennines. Brown goes on to look at a three dimensional model of the sub-surface granite as computed by the I.G.S. from geophysical data. Dennis Jackson sums up the programme by discussing, briefly, how a borehole confirmed the I.G.S. model above for a sub surface granite. |
| Master spool number: | OU3294 |
| Production number: | FOUS045K |
| Videofinder number: | 1384 |
| Available to public: | no |
