Analytical Methods:Compaction Monitoring

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Degradation processes linked to bulk density
A degree of soil compaction is inevitable and unavoidable following burial of archaeological deposits. However, soil compaction, particularly of the upper soil profile, may be exacerbated by development, recreation, cultivation techniques, and livestock trampling. The effect of soil compaction on buried archaeological artefacts and deposits may include physical disturbance (erosion, compression, breakage, and reorientation of artefacts) but it may also lead to chemical and biological changes as pore space and drainage is reduced and can accelerate erosion. Soil compaction, therefore is an important process affecting archaeological preservation and soil quality for landscape preservation. However, the effects of compaction may be highly localised, for example around feeding troughs and gates, and in established wheel ruts.

Approaches to monitoring bulk density
Discreet measurement of bulk density can be taken in the field using a penetrometer, alternatively undistubed samples of known volume can be removed form the soil and analysed in the laboratory. A high tech approach is to use neutron-gamma probes either to measure surface compaction or installed in access tubes to measure density through the soil profile.

Sampling strategies
The sampling strategy will depend on the question. To monitor the effects of localised events such as piling or trampling requires targeted sampling points, monitoring site wide changes, for example in response to land use change, will require a grid of points across (and possibly vertically through) the site.

Related techniques

 * Bulk density

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