Local Geology
Today, East Anglia is characterised by farmland plains, rolling hills, fens and waterways. But if we could peel away the surface of the landscape - the cities, towns, trees and fields - we would see the rocks beneath. These rocks tell a story of a landscape once very different to that of today, and we find that the geological history of East Anglia is more varied than the landscape suggests.
Making the basement
In the ancient past (before about 250 million years ago), the muds and sands of East Anglia were caught up in the collisions of drifting continents, and squeezed and altered into hard rocks.
Tropical sea-beds
Between about 250 and 55 million years ago, this basement sank beneath tropical seas and was covered by muds, limestones and sandstones - some of the extinct marine life and dinosaurs from this time are displayed in the gallery.
Raising and tilting
From about 55 to 2 million years ago, the area that is now East Anglia was raised above sea-level and tilted gently to the east. Rivers started to remove soil, creating valleys and lowering the land back towards sea-level. Periodically the sea invaded the eastern edges of East Anglia. There was general cooling of the climate.
Erosion cut across the layers and formed the landscape we see today. If we could cut a section through the landscape we would see the layers:
The Ice Ages
The last 2 million years have seen repeated episodes of changing climate, culminating about 500 thousand years ago in the Anglian glaciation when an ice sheet covered the whole of East Anglia.
The diagram shows the extent of ice coverage over East Anglia, 500 thousand years ago. The arrows indicate the direction of the ice flow.
The climate was colder than now, and the East Anglian ground was permanently frozen. There were also short intervals of warmer conditions. These violent climatic swings resulted in frequent collapse and slumping of valley walls. With the lifting of the most recent cold episode, some 12,000 years ago, sea-level has risen, and the Fens, north Norfolk coast, the Broads and other river valleys, have been flooded, and filled with mud and peat.
Although the Ice Ages were a time of harsh conditions in East Anglia, some animals were well suited to the freezing temperatures. And in the warmer periods, the climate was temperate enough for grasslands to develop - evident in the remains of hippos and elephants found in Cambridgeshire.
