Essex Field Club on Facebook

Video about the Club

Grapholita jungiella
find out more... Grapholita jungiella Copyright: Ben Sale

Essex Field Club
Essex Field Club
registered charity
no 1113963
HLF Logo A-Z Page Index

Visit Our Centre

EFC Centre at Wat Tyler Country ParkWe are open today

We are normally open to the public at our centre at Wat Tyler Country Park every Saturday, Sunday and bank holiday 11am-4pm, check. We are also open 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

Harts Wood , BRENTWOOD , Brentwood District, TQ603923, General geological site

hide/show OS map  

Site name: Harts Wood

Grid reference: TQ 603 923

Brief description of site:

Potential exposures of Warley Gravel and Bagshot Sand in ravines or stream banks and in the roots of fallen trees. Harts Wood is owned by Brentwood Council and accessible at all times.



The bedrock of Harts Wood consists of Bagshot Sand. This formation is as a result of the gradual shallowing of the London Clay Sea about 50 million years ago. The sediment being deposited on the subtropical sea floor started as a mud that we now know as London Clay and became more and more sandy until eventually it consisted entirely of the fine yellow sand we now call Bagshot Sand. This sand was probably laid down across most of Essex in a great complex of river deltas and all that now remains of it are isolated patches on the tops of these hills in south Essex, the rest having been removed by the intense erosion of the Ice Age.

On top of the Bagshot Sand in this area is an extensive spread of ‘Warley Gravel’ (called Stanmore Gravel on modern geological maps), which dates from an early period of the Ice Age and may be over a million years old. The origin of the Warley gravel is unknown, but one theory is that it was deposited by a south bank tributary of the early Thames when the Thames flowed across central Essex. Numerous rounded pebbles from this gravel can be seen in the wood.

See the site account for Holdens Wood in Great Warley for more information about the Warley Gravel.


if you have an image please upload it

Geology Site Map
A-Z Geological Site Index