Section drawings are measured drawings of sections - vertical cuts though layers and structures on excavations.
The finished drawing represents the surfaces being drawn as if face-on from the side, to a scale (usually 1:10,
but for larger sections 1:20 or 1:100 is sometimes used). Sections are drawn on site, and then inked-in
(and increasingly, computer-digitised) afterwards to create a permanent record.
Sections are produced on a drawing board permanently covered by graph paper. Secured over this is a blank sheet of
semi-transparent drawing film. The section is drawn on this in pencil. If the section is to be drawn at 1:10, then
each centimetre square on the graph paper represents 10 cm on the site. Metal pins or pegs are placed at the top of
each end of the section and a string tied between them. The string is levelled using a level or total station, and
this string height is also measured against the site benchmark. Section drawings must always be carefully located
within the site grid, with co-ordinates marked for each end of the string.
The shape and detail of the various layers in the section are measured vertically downwards from the string using a
hand-tape. To locate a position along the string, another tape is strung out between the pins at either end. Context
numbers are added to each layer on the finished drawing so that they can be identified at a later date.
Sections are drawn of the sides of excavation trenches or of blocks of deliberately unexcavated material called
'baulks', showing all the layers that have been dug through. They are also drawn through individual features such as
post-holes or ditches, which are normally quarter or half-excavated first. The section is then drawn before the rest
of the fill is removed. Sections can be drawn at the end of an excavation, or they may be drawn in stages as work
continues: these are called cumulative sections. They are particularly useful for recording areas of complex
archaeology, where it may be necessary to expose all of an underlying context to fully understand it, in spite of
the fact that it lies partially under a baulk.
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