A piece of music lasting just over four hours based on estimates of global sea level changes over the past 248 million years. Limits on file sizes on Bandcamp mean that for download release this piece has been split into two parts, intended to be played without a break.
‘Sea Change’ is composed from a set of continuous sound sources, some directly related to water, some indirectly. The volumes of these sound sources are controlled directly by estimates of the rise and fall of sea levels over a quarter of a billion years. With each sea level rise of 20 metres, a new sound source is added. The higher the sea level, the denser the sound. And conversely, as sea level drops, layers of sound disappear leaving the piece less dense.
Each minute of the piece represents one million years. This massive compression of time serves two purposes: it compresses the data from the past 248 million years into a more human timescale - making the sea level changes perceptible - whilst at the same time it makes a piece of music long enough to hint at the lengthy periods of time involved.
‘Sea Change’ was composed in 2002. I acknowledge the invaluable help of Michael Northam and Achim Reichsdorf. It includes sounds based on recordings by Michael Northam, and sounds supplied by Colin Potter.
The final hour is also available as a free download: ‘One hour as sixty million years’:
jonathan-coleclough.bandcamp.com/track/one-hour-as-sixty-million-years
The poem shown in the image is by Geoff Sawers.
The source of sea level estimates used in this piece:
Haq, B. U., Hardenbol, J. and Vail, P. R., 1987, Chronology of the fluctuating sea levels since the Triassic: Science, 235, pp. 1156–1167.
In 2008, after ‘Sea Change’ was completed, Bilal Haq and Stephen Schutter published a further 300 million years of sea level change estimates: Haq, B. U. and Schutter, S., 2008, A Chronology of Paleozoic Sea-Levels Changes: Science, 322, pp. 64–68.