We have divided the county into seven regions as a practical way of describing the landscape. We are working in each region to highlight sites that represent the local geology of the area. We are also developing trails that link some of these sites with places of historical and cultural interest as well as with other walking routes. We try to work in partnership with local communities to enable geology and landscape to be included in their own heritage projects.
Cambridgeshire is known for its fenland landscape, a unique area of extensive low-lying land that has been formed by a complex, dynamic and rich geological history. Clues to this history, can be found by studying the surprisingly diverse deposits that remain, including sands and gravels from the last 2-3 million years or so (Quaternary), as well as freshwater peat, tidal flat sediments and river alluvium deposited in the years since the last ice age (Holcoene) and it is these that give much of the north of the county its distinctive character. The transition from the low fen basin (which lies below sea level in some places) to the surrounding ‘highland’ forms a significantly important cultural area, the fen edge, with characteristic landscape features of its own.
The chalk escarpment that forms the southern part of the county dates from the Cretaceous and provides Cambridgeshire with a share of England’s chalk downland, extending as the Chilterns to the south west and the Yorkshire Wolds in the north of the country. The valley of the River Cam, lying to the north of the escarpment, receives much of its water from chalk springs that line the scarp slope. Two major rivers cross the county, the Ouse and the Nene, both of which now have extensive ‘washlands’ that are of high value to nature conservation. Their courses have changed dramatically over their lifetime creating many of the present day landscape features.
Less well known to most people, and in some ways less distinctive, are the ‘claylands’ that form much of the central band of the county and underlie much of the fenland in the north. Yet these clays, mostly Jurassic, and their associated sediments have some of the richest fossil deposits in the country, a few of which have become famous worldwide. Among the clays lie deposits of sandstone giving the county a small area of sandy heath, an extension of the Greensand Ridge that runs through Bedfordshire.
Over much of the clays and sandstones, and some of the chalk, lie ice age deposits from the last 2-3 million years, most of which form higher land including a ‘high’ plateau to the west of Cambridge. Finally, in the northwest of the county can be found the Jurassic formations that contain the famous limestones from which many of the important local buildings have been formed, including the cathedrals at Ely and Peterborough. They are part of the Jurassic sequence that extends south as the Cotswolds and north into Yorkshire.
© Cambridgeshire Geological Society