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Time piece from 23 to 25ns. This last slice is now practically all blank, but a few of the walls are still revealing strongly.

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

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

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Magnetometry, as discussed above, is a passive technique measuring local variations in magnetism against a localised zero value. Magnetic vulnerability study is an active method: it is a step of how magnetic a sample of sediment might be in the existence of a magnetic field. How much soil is checked depends upon the size of the test coil: it can be really little or it can be reasonably big.

The sensor in this case is very little and samples a small sample of soil. The Bartington magnetic susceptibility meter with a large "field coil" in use at Verulamium throughout the course in 2013. Top soil will be magnetically boosted compared to subsoils merely due to natural oxidation and reduction.

By measuring magnetic vulnerability at a relatively coarse scale, we can detect locations of human occupation and middens. We do not have access to a reliable mag sus meter, however Jarrod Burks (who helped teach at the course in 2013) has some exceptional examples. Among which is the Wildcat site in Ohio.

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These towns are frequently laid out around a main open location or plaza, such as this rebuilt example at Sunwatch, Dayton, Ohio. The magnetic susceptibility survey assisted, however, specify the main location of profession and midden which surrounded the more open location.

Jarrod Burks' magnetic vulnerability study results from the Wildcat site, Ohio. Red is high, blue is low. The method is therefore of great use in defining locations of general occupation rather than determining specific functions.

Geophysical surveying is a used branch of geophysics, which uses seismic, gravitational, magnetic, electrical and electromagnetic physical approaches at the Earth's surface to determine the physical homes of the subsurface - Geophysical Survey Equipment - Ground Penetrating Radar in Gosnells Australia 2022. Geophysical surveying techniques generally determine these geophysical homes together with anomalies in order to evaluate various subsurface conditions such as the presence of groundwater, bedrock, minerals, oil and gas, geothermal resources, voids and cavities, and much more.