video record
Media not available in the Digital Archive
This programme provides earth scientists with an introduction to the structure, formation and evolution of ocean crust. A quick review cf the evidence for plate tectonics is given in the early part... of the programme, followed by the more detailed ocean crust information. A great deal of use is made throughout the programme of graphicsand animation sequences and there are several filmed illustrations of various geophysical techniques.
Metadata describing this Open University video programme
Module code and title: S237, "The Earth, structure, composition and evolution"
Item code: S237; 05
First transmission date: 02-05-1981
Published: 1981
Rights Statement:
Restrictions on use:
Duration: 00:24:00
+ Show more...
Producer: Stuart Carter
Contributors: Geoff Brown; Sandie Smith
Publisher: BBC Open University
Keyword(s): Geophysics; Oceanography; Ophiolites
Footage description: Over shots of the Earth from space, Sandy Smith introduces the programme. Geoff Brown presents a brief review of the evidence, seismic and magnetic, for plate tectonics. Maps of the ocean lithosphere and animated diagrams illustrate his points. Film shots of Iceland and the 1973 Heimay volcanic eruption. Commentary by Geoff Brown explains that Iceland is a rift system along the mid-Atlantic ridge and that basaltic rocks here are actually new ocean crust which has been lifted above sea level by exceptionally high rates of magmatic activity. Also shots of undersea volcanic activity showing pillow lavas forming. Sandy Smith looks at a technique, which uses seismic waves for studying the deeper structure of the ocean crust. Animated diagrams and still graphics help to illustrate her points. This method relies on seismic waves being generated by explosions and detected at some distance by microphones on buoys. Shots of a seismic velocities chart. Shots of another seismic technique in action. This one, relying on seismic waves produced by an air gun towed in a drogue through the sea, works by analysing the waves which are reflected back to microphones also situated in the drogue. Commentary by Sandy Smith. Pointing to a graphics board, Sandy Smith briefly explains the results which can be obtained from seismic experiments such as those above. She then goes on to look at some core samples of ocean crust from the Deep Sea Drilling Project. In order to get information on the composition of deeper layers of the oceanic crust than can be reached by drilling, Geoff Brown explains that one can look at ophiolites preserved within continental masses. Shot of the Troodos Massif in Cyprus. With the aid of still graphics, he discribes the details of structure, origin and content of ophiolites which has been discovered as a result of these studies. Sandy Smith, with the aid of diagrams, explains how the age distribution of ocean crust is used to reconstruct the positions of oceans and continents in the geologic past. To end the programme, Sandy Smith briefly discusses the interaction between oceanic and continental crust which results in the formation of oceans and the movement of continents.
Production number: FOUS168B
Videofinder number: 1592
Available to public: no