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

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

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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 approaches? Contrast of the Earth Resistance information (top left), the magnetometry (bottom left), the 1517ns time piece (top right) and the 1921ns time piece (bottom left).

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Magnetometry, as talked about above, is a passive strategy measuring regional variations in magnetism versus a localised absolutely no value. Magnetic susceptibility survey is an active strategy: it is a measure of how magnetic a sample of sediment might be in the presence of an electromagnetic field. How much soil is tested depends upon the diameter of the test coil: it can be really small or it can be fairly large.

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

By determining magnetic susceptibility at a fairly coarse scale, we can find areas of human profession and middens. Regrettably, we do not have access to a trusted mag sus meter, but Jarrod Burks (who helped teach at the course in 2013) has some exceptional examples. One of which is the Wildcat site in Ohio.

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

Jarrod Burks' magnetic vulnerability survey arises from the Wildcat website, Ohio. Red is high, blue is low. The strategy is therefore of excellent usage in specifying locations of basic occupation instead of recognizing specific functions.

Geophysical surveying is an applied branch of geophysics, which utilizes seismic, gravitational, magnetic, electrical and electro-magnetic physical methods at the Earth's surface to measure the physical properties of the subsurface - Gravity Geophysical Survey Method in Iluka Western Australia 2023. Geophysical surveying techniques usually determine these geophysical properties together with abnormalities in order to evaluate various subsurface conditions such as the presence of groundwater, bedrock, minerals, oil and gas, geothermal resources, voids and cavities, and a lot more.