Simon Fraser University Museum of Archaeology and Ethnology
Did you know that it is possible to find underground archaeological
sites without excavating at all??
It's true!!
There are various ways of doing this, two ways to avoid probing into an
area and damaging artifacts are by using a proton magnetometer
and soil resistivity meter.
Wow, big words, eh ? See if you can say that ten times in a row !!
Proton Magnetometer
By taking a proton magnetometer over a site, archaeologists can very
quickly build up an clear map of many underground archaeological remains.
This instrument works by sending an electrical current into the ground and
then looking at the changes in the magnetic field.  Strong magnetic fields
are produced by things underground like buildings. Weak magnetic fields
are found where there are no hidden remains.
Archaeologists have to be careful, however, because they can
easily be led to a modern sewer system instead of a real find !!
Soil Resistivity Meter
Soil resistivity makes use of the way that disturbances in the ground,
such as buildings, pits and ditches make differing degrees of resistance to
the passage of an electrical current.  The soil above postholes and ditches,
for example, will be drier than undisturbed soil and so it gives a different
resistance reading (a higher one) than the rest of the soil around it.  BUT,
filled in ditches, pits and postholes are damper and will give lower resistance than
undisturbed soil.
I know, I know, a bit tricky but, in a nutshell, these instruments can
let archaeologists "look" underground without moving anything by
sending down in to the ground certain types of electrical currents which
can detect buried sites and objects.