Experts in geology are proving that time travel is possible after uncovering the secrets of life in Brentwood 50 million years ago.

The Essex RIGS Group, which stands for Regionally Important Geological Sites, are exposing a sand pit in Thorndon Country Park that is known to be made of material from the Eocene Period.

Supporters of the organisation won't be walking with dinosaurs, as the giant beasts became extinct 15 million years prior to that, but they could be lucky enough to find the fossilised remains of the teeth of ancient sharks when Brentwood was in a tropical sea.

The latest excavation took place on Sunday and follows the recent exposure of a gravel pit in woodland at Scrub Hill on Warley Common that provided a snapshot of life in the Ice Age, about 450,000 years ago.

The gravel pit, a 1.5 metre high section through glacial gravel, is to be designated a Regionally Important Geological Site.

Essex RIGS Group chairman Gerald Lucy explained: "The geology of the area is quite straightforward. It consists of old rocks - London clay and above that Bagshot sand. These two rocks were laid down in a tropical sea 50 million years ago. If you go to Walton on the Naze you can find fossils of animals that lived in the sea during that period. It is possible we might find the teeth of ancient sharks in Brentwood."

Mr Lucy, the author of the geology book Essex Rock, continued: "Then 49.5 million years later the Ice Age came along and most of Britain was buried beneath a giant ice sheet which spread out from the mountains of Wales and Scotland where it was over one kilometre thick.

"What is now Brentwood was situated near the southern end of this ice sheet and the land at that time was frequently flooded by colossal torrents of melt water depositing great quantities of gravel across the whole area. Later, after the retreat of the ice, subsequent rivers created new valleys, leaving patches of this gravel isolated on higher ground."

Supporters of the Essex RIGS Group, which has Government recognition, say the Scrub Hill gravel is "somewhat of a puzzle" as it is mixed with sand and packed with extremely well rounded pebbles of flint, which could only have been shaped by rolling on a beach.

Mr Lucy said: "It is thought that the pebbles must have been transported by the ice from a much older deposit, probably one laid down in a warm shallow see that covered Brentwood many millions of years before, and now completely destroyed."

The gravel pit is situated at OS Grid Reference TQ 6045 9110 but it is difficult to find in the woods. Anyone wishing to visit is advised to call the Brentwood Countryside Management Service on 01277 261111 ext. 504 for directions.

The group are planning to conduct talks at the site next year.

Anyone interested in becoming a supporter of the Essex RIGS Group should write to 7 Barnards Court, Church Street, Saffron Walden Essex CB10 1JS.

Published Thursday November 29, 2001