On the site of the Skyline Business Park diggers found a series of enclosures including an Iron Age ditch boundary overlaid with a Roman enclosure.
Fragments of pottery and burnt flint were recovered from the presumed farmland site, which is believed to have been used to grow grain and rear animals.
Michael Leach, secretary of the Essex Society For Archaeology and History, which was founded in 1852, said: "It is exciting to see the history of the site, and how it fell out of use and was taken up again.
"This preliminary investigation also found fragmentary remains, but it is not yet known if these are of human or animal origin."
The society conducts rescue investigations in advance of developments to establish the history of the land before expansion makes it impossible.