Archaeologists have found a number of stone artefacts, including an ancient flint tool during a dig in St Brelade.
Dig leader Matt Pope said said: "We have taken some samples which will tell us how old the sediments are that contain these stone artefacts."
He said: "We suspect that they will be less than 50,000 years old.
"Maybe anywhere between 50,000 and 40,000 years ago, but we will have to prove that with some science."
Dr Pope said engineers were stabilising the cliff alongside the excavation.
The three-week dig at La Cotte was carried out by archaeologists from UCL Institute of Archaeology, Wessex Archaeology and the University of Wales.
Dr Pope said the previous dig at the west ravine site was 82 years ago in 1940, "just days ahead of the German invasion" during World War Two.
In July, the Prince of Wales became the patron of the project at the site, which he visited as a student in 1968.