The repository includes the data for electrical resistivity and magnetic gradiometry surveys undertaken at Milking Gap, Northumberland in June 2023 as part of a PhD project focusing on landscape and geophysical surveys of the Vallum of Hadrian's Wall.

The work was undertaken by Sam Bithell at Durham University Earth Sciences Department

The repository format is as follows:

"1-ERT_data"

	"1-Data"

		- Raw .res files for each of the three surveyed transects containing the data and error measurements for the survey.
		- There is one file per transect.

	"2-Electrode_positions"
	
		- Three .csv files (one per transect) containing XYZ data for every electrode position in each transect.
			- The 1st field (X) is the in-line distance along the profile from electrode #1
			- The 2nd field (Y) field is the off-line distance of each electrode (0 in all cases)
			- The 3rd field (Z) is the elevation of each electrode extracted from 1m resolution Environment Agency (2023) LiDAR data
			- All units are in metres, elevation is based on Ordnance Survey Datum

		- Three .gpkg files (one er transect) with the spatial data for the locations of each transect

"2-Mag_data"

	"1-MGR"
		- 6 .mgr files which are the raw exported data from Geomar Software's data acquisition software.
		- Each file corresponds to a separate data collection session, across several days
		- These correspond to the raw data streams from the GPS and magnetometry equipment as it was gathered in the field
	"2-XYS"
		- The data for each sensor of the magnetometry survey, corresponding to each .mgr file.
		- Processing of the .mgr file extracted each individual sensor, and interpolated magnetometry readings on the basis of the GPR coordinates.
			- The .xyz files are therefore the raw magnetometry readings and corresponding GPS positions.
			- There are 8 fields to each file:
				- 1: X coordinate in metres (UTM zone 30N)
				- 2: Y coordinate in metres (UTM zone 30N)
				- 3: nT/m (magnetic gradient measurement)
				- 4: GPS quality
				- 5: Number of satellites
				- 6: GPS HDOP
				- 7: Elevation (m)
				- 8: Timestamp
	- Detail of the data collection software MLGrad601 is here (https://geomar.com/trms/tn-ml601/MLgrad601.pdf) and the initial processing software MultiGrad601 is here(https://geomar.com/trms/tn-ml601/MultiGrad601.pdf). The software is created by Geomar Software Inc. (https://www.geomar.com/)