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Colias croceus
find out more... Clouded Yellow - 20th August 2013 Copyright: Ian Rowing

Essex Field Club
Essex Field Club
registered charity
no 1113963
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EFC Centre at Wat Tyler Country ParkIn January we are only open to the public at our centre at Wat Tyler Country Park on Wednesdays 10am-4pm.
Autumn recording Record Grey Squirrel Record Fly Agaric
Record Ivy Bee
Record Wild Teasel
Record Sloe, Blackthorn
Record Garden Spider Record Nigma walckenaeri spider

Geology Site Account

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Ovington Hall Sarsen Stone, OVINGTON, Braintree District, TL763426, Potential Local Geological Site

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Ovington Hall sarsen stone

An exceptional sarsen stone, 2 metres (6'6") long, with a mammillated surface can be seen near the churchyard on the track leading to Ovington Hall.

Sarsens are extremely hard boulders of sandstone formed around 55 million years ago when the climate of Britain was hot and a layer of sand beneath the surface of the ground became cemented with quartz. They are thus very resistant to erosion and have survived the rigours of the Ice Age. They probably originated on the chalk downland of south Cambridgeshire and after retreat of the ice they became concentrated in river valleys such as The Stour.

The remarkable 'mammilated' surfaces are called ‘growth structures’ which were formed as the quartz slowly crystallised between the sand grains.

 

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