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The Effect of Weather on Resistivity Measurements Over a Known Archaeological Feature

出版	1997
URL	http://books.google.com.hk/books?id=AnW7zQEACAAJ&hl=&source=gbs_api

註釋This work studies how changing weather conditions affected resistivity measurements over a Roman ditch at Caistor St. Edmund, Norfolk. Measurements were taken monthly from May 1995-June 1996, using five experiments:'two Twin probe area surveys, with probe spacings of 0.5m and 1.0m; a Twin probe pseudosection transect, with probe spacings 0.5m-5.0m; a Vertical Electrical Sondage along the ditch using a Wenner array, and a control measurement in undisturbed ground, both using probe spacings from 0.5m-5.Om. The early chapters cover the resistivity method in archaeology, the theory underlying the Wenner, Schlumberger and Twin probe arrays, the theory of pseudosections, and the effect of weather on soil moisture content. Investigations by other workers are discussed. The ditch was always detectable as a low resistance anomaly. The correlation between the apparent resistivity and moisture input was greatest with 3-4 weeks of moisture input, at small probe separations. For large probe spacings, the Wenner apparent resistivity measurements achieved the highest correlation at 35-37 weeks of moisture input, and for the Twin array pseudosection, the highest correlation was at 28-38 weeks. This also applied to cumulative sunshine hours. There was correlation between apparent resistivity and the calculated value of Soil Moisture Deficit. It is concluded that the soil at Caistor has two layers, the upper responding quickly to changes in the weather, whilst the lower responds over a much longer timescale. The objective of the study was achieved.