SECRETS of prehistoric England have been uncovered by research at the Almondsbury interchange.

Underground samples taken 25 years ago from beneath the M4/M5 junction, including thousands of fossils, have shown evidence of major flooding across southern England millions of years ago.

Comparisons of species in two different layers of rock, conducted as part of research at University of Worcester, concluded that, contrary to some academic theories, they were not caused by a one-off flood but by separate flooding events.

University of Worcester student Tiffany Slater, 24, a second year undergraduate Biology student, originally from Kentucky, USA, who conducted the research, said: “It’s very exciting to see an ecosystem change from mostly sharks to mostly bony fish over 200 million years ago, all right underneath the M4-M5 motorway junction.”

“It has never quite been determined whether these bone beds were linked to the same event or whether they were separate events,” said Tiffany, whose paper has been published in the journal Proceedings of the Geologists' Association.

“We knew there were several flooding events, however it was thought that this upper bone bed happened when storms came in and ripped up the bottom bed and worked it into higher sediments.

“It’s clear now that’s not the case.  This bottom bone bed stayed put and the next bed was new organic material swept in by the sea.”