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Much of the image consists of blank areas now with little or no radar response. The "yard" wall is still showing strongly, however, and there are continuing tips of a hard surface area in the SE corner. Time slice from 23 to 25ns. This last slice is now practically all blank, however a few of the walls are still revealing strongly.

How deep are these slices? The software 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 think that each slice is about 10cm and we are just coming down about 80cm in overall.

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

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Magnetometry, as talked about above, is a passive strategy determining local variations in magnetism versus a localised zero value. Magnetic vulnerability survey is an active method: it is a procedure of how magnetic a sample of sediment might be in the existence of a magnetic field. How much soil is checked depends on the diameter of the test coil: it can be very little or it can be fairly big.

The sensor in this case is very small and samples a tiny sample of soil. The Bartington magnetic vulnerability meter with a big "field coil" in usage at Verulamium throughout the course in 2013. Top soil will be magnetically improved compared to subsoils merely due to natural oxidation and decrease.

By measuring magnetic vulnerability at a relatively coarse scale, we can find areas of human profession and middens. We do not have access to a trusted mag sus meter, but Jarrod Burks (who helped teach at the course in 2013) has some outstanding examples. One of which is the Wildcat website in Ohio.

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These villages are typically laid out around a central open location or plaza, such as this reconstructed example at Sunwatch, Dayton, Ohio. The magnetic vulnerability study helped, nevertheless, define the primary area of occupation and midden which surrounded the more open location.

Jarrod Burks' magnetic susceptibility study results from the Wildcat website, Ohio. Red is high, blue is low. The technique is therefore of great usage in defining locations of general profession rather than determining specific functions.

Geophysical surveying is a used branch of geophysics, which utilizes seismic, gravitational, magnetic, electrical and electromagnetic physical methods at the Earth's surface to measure the physical properties of the subsurface - Glad You Asked: What Are Seismic Surveys? in Wexcombe Oz 2023. Geophysical surveying approaches usually determine these geophysical properties together with abnormalities in order to evaluate different subsurface conditions such as the existence of groundwater, bedrock, minerals, oil and gas, geothermal resources, spaces and cavities, and a lot more.