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Book Chapter

6. British clay stratigraphy

Published:
January 01, 2006

Abstract

There are three principal types of stratigraphy, each with its own terminology:

  • geochronolog—units of geological time (e.g. period, epoch), with a parallel and exactly corresponding stratigraphy;

  • chronostratigraphy—time-rock units or time-stratigraphic units represent stratified rock successions (e.g. system, series, etc.) assigned to geological time units;

  • geochronometry—the measurement of absolute time in years as numerical ages (e.g. 345 Ma), principally by means of radiometric dating, but increasingly, in Phanerozoic rocks, by the numerical dating of Milankovitch cycles.

This has led to some confusion. Current recommendations, led by the Geological Society (Zalasiewicz et al.. 2004) are to adopt the geochronology scheme, which has been used in this chapter.

Part of the geological timescale, covering the last 545 million years of earth’s history (Phanerozoic—from the greek meaning ‘visible life’), is shown in Table 6.1 (Gradstein & Ogg 1996) with the youngest at the top. This shows the broadest sub-divisions of era and period (the Neogene and Palaeogene are often referred to as the Tertiary, though this name may fall into disuse). The names for the eras derive from the greek meaning ‘ancient’, ‘middle’, and ‘new’ life. Periods further sub-divide into early, middle, and late (or in some cases simply early and late), and thence into epochs and ages (refer to Appendix C). Time before the Phanerozoic is usually referred to as the Pre-Cambrian.

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Geological Society, London, Engineering Geology Special Publications

Clay Materials Used in Construction

G. M. Reeves
G. M. Reeves
UHI Millennium Institute, Thurso, UK
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I. Sims
I. Sims
STATS Limited, St Albans, UK
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J. C. Cripps
J. C. Cripps
University of Sheffield, UK
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Geological Society of London
Volume
21
ISBN electronic:
9781862393837
Publication date:
January 01, 2006

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