Wednesday, 21 October 2009

Natural chronographics

Some natural processes produce a sort of chronographic display of their own – for example, the rings in sawn tree trunks represent the history of its growth, and geological strata represent the history of a landscape.

Tree rings can be crossdated to establish specific years in the tree’s history.
Image from Laboratory of Tree Ring Research at the University of Arizona.

Tree rings
As a page from the Laboratory of Tree Ring Research at the University of Arizona explains:
Many trees in temperate regions (those with a strong seasonal climate) produce annual growth layers that appear as rings in a cross sectional view of a tree stem. Variations in growing conditions from year-to-year produce a sequence of wide, narrow, and average ring widths. Over time the sequence forms a unique pattern that can be used like a fingerprint to determine the calendar year in which each ring was produced. [...]
Events in a tree’s life that have a recognizable impact on its growth may also be dated once the dates of the annual rings are known. Low to moderate intensity fires that burned through a forest may injure or scar surviving trees, leaving a clear record of their passage.
In at least one case the realisation that naturally occurring visual forms represent past time dawned during the same period as the early paper visualisations such as those of Barbeu-Dubourg and Priestley. This is the case with Hutton’s work on the formation of the earth.

Strata in rock caused by deposition over centuries.
Lake Bolsena, Italy. Photo: Stephen Boyd Davis.

James Hutton (1726-1797) sought to explain rock formations. His Theory of the Earth; or an Investigation of the Laws observable in the Composition, Dissolution, and Restoration of Land upon the Globe and Concerning the System of the Earth, its Duration and Stability put forward the idea that the layers to be seen where rock is exposed represent ancient depositions such as occur under water, and that places where the layers are uptilted or broken record violent subsequent upheavals.

An ironic outcome of the work in geology was to move the goalposts – at least at one end of the pitch. The beginning of time moved away to an almost ungraspable distance rather than the relatively comfortable proximity of, say, 4004BC calculated by Archbishop Ussher. The many universal chronologies and chronographies which contained all history from the beginning of all things to the present day within roughly 6000 years would become increasingly out of step with the realisation of the real extent of the past.

Event-based and time-based
These natural chronographics record time unequally: sedimentary deposit during one century may produce a thick layer of rock while that of another century ends up as only a narrow band. A year of strong growth produces a broad tree ring while one of poor growth makes a narrow one. These are effectively event-based representations. A time-based representation, on the other hand, uses what we might call Newtonian time – a regular, uniform, clock-like scale, in which events appear. 

Further reading on the Web:

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