Her most recent discovery was aided by soil specialist Sarah Sherwood and UCLA archaeologist Tom Wake.
Dr Sherwood said: “When we got the chemistry results back, I did a double-take.
“There were really high levels of things that I never would have thought would be there, such as calcium and phosphorous.
“The soil chemistry showed high levels of elements that are key to plant growth and essential for high yields.
“Everywhere else on the island the soil was being quickly worn out, eroding, being leeched of elements that feed plants, but in the quarry, with its constant new influx of small fragments of the bedrock generated by the quarrying process, there is a perfect feedback system of water, natural fertiliser and nutrients.”