Essex Geology
Deep Time Story of the County of Essex
Deepest History
500 million years ago, the area of Essex was a sea floor just off the continent of North Africa and close to the South Pole.
By 300 million years ago, Essex was part of a continental fragment colliding with North America – including Scotland – and its rocks were hardened during the big squash. These rocks are now the deep 'basement' of Essex.
Deserts to Dinosaurs
250 million years ago, before the age of the Dinosaurs, Essex was a desert upland in the middle of a vast continent. The old, hard rocks were being eroded.
By 200 million years ago, tropical seas had spread around dinosaur-infested forests. The old rocks made an island.
Buried Island
If you could dig down 1000 feet (300 metres) under Essex you would reach that dinosaur island.
All trace of forests and animals have been swept away from the eroded surface of the island, so there are no dinosaur fossils in Essex.
By 100 million years ago the sea flooded across the island to spread sands and then a thick layer of white chalky limestone all over the island.
Pebbles and Clay
The North Atlantic Ocean began to open out to the west, the land of Essex lifted, limestone hills were worn down and flints were eroded out - many were tumbled on beaches to form pebble gravel layers.
After 55 million years ago, a deep sea fed by muddy rivers deposited thick clay across the sea bed, together with the remains of many plants such as palms and cinnamon, and animals including birds, sharks, turtles, and tiny horses. Atlantic volcanoes poured their ash into the sea.
The Alps and the Thames
Colliding continents pushed up the Alpine mountain chain, bending the crust to form the vale of the Thames river system through mid Essex.
Global cooling led to the present Ice Age, with warm periods such as the one we are in right now. About two million years ago offshore sandbanks formed red shelly sandstone layers across north Essex. As the sea retreated, the ancestral River Thames spread a succession of flint-rich river gravels across mid-Essex and out across the area where the North Sea is now.
Ice and People Cover Essex
An ice sheet covered most of Essex during a particularly icy stage 450,000 years ago. The moving ice dumped its load of boulder clay as far south as Hornchurch in Essex and the ice sheet diverted the Thames towards its present-day course.
During the past million years of this cold era, humans visited and lived in and around the area of Essex, leaving masses of flint tools and tool-making debris on the banks of the ever-changing Thames rivers.
Dig and Discover
The eroding patchwork of rocks
is there to reveal its story.
If you care to dig and discover it
with Essex Rock and Mineral Society -
just Enquire Within!
Deepest History
500 million years ago, the area of Essex was a sea floor just off the continent of North Africa and close to the South Pole.
By 300 million years ago, Essex was part of a continental fragment colliding with North America – including Scotland – and its rocks were hardened during the big squash. These rocks are now the deep 'basement' of Essex.
Deserts to Dinosaurs
250 million years ago, before the age of the Dinosaurs, Essex was a desert upland in the middle of a vast continent. The old, hard rocks were being eroded.
By 200 million years ago, tropical seas had spread around dinosaur-infested forests. The old rocks made an island.
Buried Island
If you could dig down 1000 feet (300 metres) under Essex you would reach that dinosaur island.
All trace of forests and animals have been swept away from the eroded surface of the island, so there are no dinosaur fossils in Essex.
By 100 million years ago the sea flooded across the island to spread sands and then a thick layer of white chalky limestone all over the island.
Pebbles and Clay
The North Atlantic Ocean began to open out to the west, the land of Essex lifted, limestone hills were worn down and flints were eroded out - many were tumbled on beaches to form pebble gravel layers.
After 55 million years ago, a deep sea fed by muddy rivers deposited thick clay across the sea bed, together with the remains of many plants such as palms and cinnamon, and animals including birds, sharks, turtles, and tiny horses. Atlantic volcanoes poured their ash into the sea.
The Alps and the Thames
Colliding continents pushed up the Alpine mountain chain, bending the crust to form the vale of the Thames river system through mid Essex.
Global cooling led to the present Ice Age, with warm periods such as the one we are in right now. About two million years ago offshore sandbanks formed red shelly sandstone layers across north Essex. As the sea retreated, the ancestral River Thames spread a succession of flint-rich river gravels across mid-Essex and out across the area where the North Sea is now.
Ice and People Cover Essex
An ice sheet covered most of Essex during a particularly icy stage 450,000 years ago. The moving ice dumped its load of boulder clay as far south as Hornchurch in Essex and the ice sheet diverted the Thames towards its present-day course.
During the past million years of this cold era, humans visited and lived in and around the area of Essex, leaving masses of flint tools and tool-making debris on the banks of the ever-changing Thames rivers.
Dig and Discover
The eroding patchwork of rocks
is there to reveal its story.
If you care to dig and discover it
with Essex Rock and Mineral Society -
just Enquire Within!
