Locating the pits

Dr Robert Philpott, head of archaeology at National Museums Liverpool, mapping New River II with a total station

Archaeologists used a Global Positioning System (GPS) and a total station to establish a grid of pits every 6 metres across each village. The GPS allowed team members to assign each STP two coordinates, a northing and an easting, on the Universal Transverse Mercator Coordinate System. UTM coordinates allow archaeologists to locate the exact position of a pit on the surface of the earth, and allows excavations on Nevis and St Kitts to exist in the same grid system as excavations elsewhere in the world.

map 

Digitised map of the New River villages showing shovel-test-pits, extant architecture, and roads

In this video Fraser Neiman explains how the Global Positioning System antenna uses satellites to locate the position of the GPS unit on the ground at New River, Nevis.

Transcript

Fraser Neiman: Through a process of triangulating from this antenna to multiple different satellites, the GPS unit is able to contact the satellites and figure out where it is in reference to the satellites. Now, that's really incredibly useful because the satellites allow us to place the location of the GPS unit in what's called the 'real earth coordinate system', that is to say, we can place the location of this unit in terms of latitude and longitude, and then through the software on this unit, that allows us in turn to project those latitude and longitudinal readings onto a real earth coordinate system. There are whole bunches of these. But the one that we use is the Universal Transverse Mercator system - the UTM system - and that's going to be a grid - an imaginary grid - which covers all of Nevis and big chunks of the Caribbean. And so we are able to make our maps of these terrace systems and have them register to that UTM system.