Interpreting archaeological site plans

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Archaeologists have to draw the features they excavate to create the most complete record they can. Eventually a complete site plan can be created, showing the phases of its development.


Some conventions are used on site plans. For instance, they must all have north arrows so that you can orientate them on a map, such as in the plan of Saunderton villa your teacher will give you.


Some site plans have one picture showing where the excavation was before homing in on the excavation site plan, like the ones your teacher will give you of Coldharbour Farm in Aylesbury. The location map shows nearby grid references to help tie it into the national grid referencing system.


The excavation plan itself is overlaid by a grid to make it easier to reference features in the excavation trench. There is a scale that shows how large all of these features are. The north arrow points to the right.

The limit of the trench is marked with a dot-dash line. Limit of the excavation


Symbol showing the location of a section dug through the pitWhere the archaeologists have dug into them is recorded as a section. You can see that the archaeologists did not dig any whole ditch or pit but sections at intervals, where they cross each other and at the ends of ditches.


You can see long, thin ditches or gullies, which may have supported a fence-line or been drainage channels.



The thin straight gullies are modern field drains.

 Field drain

The wider ditches were probably boundaries marking out an enclosure. Ditch


The almost circular ditches are often interpreted as the drainage gullies around a prehistoric round-house.

Ring-ditch around a round-house


Post-holeThe small irregular round features are post- and stake-holes. When a post or stake rots in situ or is taken out, it leaves a hole behind. This eventually fills up with silt, but the silt will usually be of a different colour to the soil into which the stake or post was driven. Stakes would be used to create a fence-line. Posts could be the foundation of a round-house, four-post granary or two-post drier.


Arc of post-holesCan you see any lines or arcs of post-holes? Some stake and post-holes will have been destroyed completely by ploughing, so archaeologists often get incomplete lines or arcs of post-holes.



PitThe larger irregular features are pits. Pits were used to discard rubbish, to store grain and probably for placing ritual deposits to ensure the success of the settlement.


So many pits were dug that they often cut into each other.

Several pits intercutting each other


Other site plans can be the result of a topographic survey where the lumps and bumps on the ground have been measured and mapped rather than an excavation. Your teacher will give you the English Heritage survey of Ivinghoe Beacon. The plan is interpreted using colours that refer to a key.


The pink areas represent the hillfort bank and ditch, red represents house platforms, blue represents barrows and so on.

Hillfort bankKey to the hillfort bank


Hachure symbol showing the line of the slopeAny slopes recorded in this survey are represented by a hachure. This symbol records the length of the slope and its direction, the thicker end being the top of a slope.


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