Stratigraphy Cake
YAC Attack 148! Stratigraphy Cake
When most people think about archaeology, they think about excavations.
- But is excavation as simple as digging a big hole in the ground and looking for old stuff?
Before archaeologists even begin to dig there is a lot of preparation to be done. They need to decide exactly where they are going to put their trenches. To do this, archaeologists will look at aerial photographs, maps and other historical records to see if there is evidence that might point to earlier buildings or other features.
Archaeologists often do a geophysics survey too, in order to pinpoint places on the site where there is likely to be archaeology. They would use this information to help them decide where to dig.
The next step is to ‘open’ (or start to dig) the trench. Archaeologists often dig in ‘spits’ across a trench taking off a small layer of soil at a time. This allows them to record any features and changes in soil type and colour. Each of these layers in given a ‘context’ number.
Archaeologists need to know exactly where they have placed their trench, its size, and its height above sea level, so that they can map any features and finds that they discover. To do this, they will use a reference point called a benchmark.
Benchmarks were created as part of the Ordnance Survey mapping project of Britain (which was started in the 18th century). They are fixed points that have a known height above sea level; archaeologists use special surveying equipment to map their trenches in relation to local benchmarks. They can then plot exactly where their trenches are. Benchmarks can be found on some buildings and other permanent landmarks, many are found on churches.
ACTIVITY: Are you looking for an unusual way to investigate archaeology? Try making our incredible stratigraphy cake to discover more about how layers build up and what an archaeological section looks like.
