This tape will self-destruct
Adler de Wind wonders what geo-pedagogues will do when nobody can remember how a tape recorder works.
Geoscientist 19.11 November 2009
When I was growing up, not very far from the Cape of Good Hope, I asked my father why, in all those books about derring-do in the Sahara that I used to read, they talked about night falling almost with a bang. Why should the night fall more quickly in Ouagadougou than in Kommetje, I asked?
My father showed me a vinyl disc playing on the turntable. The surface of the Earth travels faster at the equator, he said, like the outer grooves of the LP. So it takes less time to travel through the twilight zone there than it does at higher latitudes – where the ground travels a smaller circle in the same 24 hours. It kept me awake at night for a bit, but the analogy worked. Now, hardly anybody sees a turntable any more.
I find that I can index-fossil my life’s phases by tape recorders. In the late 50s we had the old Sonomag half-track mono machine, the size of a tea crate. Then came the luggable Philips quarter-track mono machine, which could record at four different speeds – use the high speed for higher quality. Then there was the Tandberg four-track stereo machine with its interesting four-way joystick. And then came a (second-hand) Ferrograph, king of the audio jungle, and an Akai with its strangely exciting oversize external pinch-wheel, and finally a mighty TEAC. And then what happened? Cassettes invaded. Reel-to-reel became extinct. Then cassettes succumbed in the digital mass extinction. Now we are come to our ipods.
And yet, how useful the tape-recorder analogy was! A spreading centre like the Mid Atlantic Ridge is like a tape that records the polarity of the Earth’s field as the lavas slowly congeal and move away. Sedimentation records the events in a shallow sea like a magnetic tape, moving slowly when sedimentation rates are low and quickly when high. When rates are low, there is a chance that information might be lost, too, just like a recording made at one and seven eighths inches per second, when you got drop-outs – disconformities in the music - from the imperfections of the magnetic coating.
Yet already, young people reading such explanations may be struggling to know what we are talking about. How can we adapt our explanations to new technology? And will it even be possible? Will download speeds, or pixel concentrations or the packet switchstream system, ever provide us with the rich imagery that the tape or vinyl recording machine once did, with its simple ideas and real, moving parts? Somehow, I doubt it; but if you have any suggestions, please share them!
• Any ideas? Write directly to the Editor at ted.nield@geolsoc.org.uk.