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Much of the image includes blank areas now with little or no radar reaction. The "yard" wall is still showing highly, however, and there are continuing suggestions of a hard surface in the SE corner. Time slice from 23 to 25ns. This last piece is now almost all blank, but a few of the walls are still showing highly.

How deep are these pieces? The software I have access to makes estimating the depth a little tricky. If, however, the leading 3 pieces represent the ploughsoil, which is probably about 30cm think, I would guess that each piece has to do with 10cm and we are only coming down about 80cm in overall.



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Thankfully for us, the majority of the websites we are interested in lie simply listed below the plough zone, so it'll do! How does this compare to the other techniques? Comparison of the Earth Resistance data (leading left), the magnetometry (bottom left), the 1517ns time piece (leading right) and the 1921ns time slice (bottom left).

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Magnetometry, as gone over above, is a passive strategy measuring regional variations in magnetism against a localised zero value. Magnetic susceptibility study is an active technique: it is a measure of how magnetic a sample of sediment could be in the presence of an electromagnetic field. How much soil is checked depends upon the diameter of the test coil: it can be very small or it can be relatively big.

The sensing unit in this case is very small and samples a tiny sample of soil. The Bartington magnetic susceptibility meter with a big "field coil" in use at Verulamium throughout the course in 2013. Top soil will be magnetically enhanced compared to subsoils just due to natural oxidation and reduction.

By determining magnetic vulnerability at a fairly coarse scale, we can find locations of human occupation and middens. We do not have access to a reputable mag sus meter, however Jarrod Burks (who assisted teach at the course in 2013) has some excellent examples. Among which is the Wildcat site in Ohio.

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These villages are typically laid out around a main open location or plaza, such as this rebuilt example at Sunwatch, Dayton, Ohio. Sunwatch Town, Dayton, Ohio (image: Jarrod Burks). At the Wildcat website, the magnetometer study had actually located a range of functions and homes. The magnetic vulnerability survey assisted, however, define the main area of profession and midden which surrounded the more open area.

Jarrod Burks' magnetic susceptibility study results from the Wildcat site, Ohio. Red is high, blue is low. The strategy is for that reason of excellent use in defining areas of general profession instead of identifying specific features.

Geophysical surveying is a used branch of geophysics, which uses seismic, gravitational, magnetic, electrical and electromagnetic physical methodologies at the Earth's surface to measure the physical homes of the subsurface - Geophysical Survey - Salisbury Archaeology in Beechina Oz 2023. Geophysical surveying techniques generally determine these geophysical homes together with anomalies in order to assess numerous subsurface conditions such as the presence of groundwater, bedrock, minerals, oil and gas, geothermal resources, spaces and cavities, and much more.