Posthole

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In archaeology a posthole is a cut feature used to hold a surface timber or stone. They are usually much deeper than they are wide although truncation may not make this apparent. Although the remains of the timber may survive most postholes are mainly recognisable as circular patches of darker earth when viewed in plan. Archaeologists can use their presence to plot the layout of former structures as the holes may define its corners and sides.

Fig 1. types of post hole

[edit] Interpretation of postholes

Postholes are different from stake holes in that the cut is dug for the post rather than created by the driving in of the stake. this means there is some voided space that has to be filled in once the post is in place. This material is post packing and is one the main ways of differentiating postholes from stake holes in plan. The shape and structure of the contexts within a posthole can also shed light on past activity. A post was purposely removed, then the action of rocking it back and forth leaves tell-tale evidence in the profile of the posthole which archaeologists can recognise. A post may have rotted in place leaving a postpipe or still be surviving (See the section in Fig 1). Archaeologists can use their presence to plot the layout of former structures as the holes may define its corners and sides. postholes may also be dug on alignments of backfilled ditches were boundaries have been upgraded from simple ditch enclosures into structural ones.

[edit] Dangers of posthole interpretation

The relative frequency of postholes as a feature in most eras combined with a lack of good information on the phasing of postholes, which often occurs onsite due to horizontal truncation or a failure to spot postholes at the level they were cut from, can lead to a clutter of postholes that invites imaginative interpretations. The human mind seems quite capable of creating patterns and the temptation to see structures that are not there or tenuous at best is quite strong. It is considered good practice that supporting evidence from multiple sources on site like the perceived structures alignments with other features onsite should be taken into account before any hard interpretation is made as to whether postholes with no stratigraphic relationship to each other are truly associated.