The geology of Cambridgeshire, so far as the underlying strata are concerned, is not complicated; the superficial deposits, however, exhibit considerable variety, and their origin is still in many cases a subject for discussion.
The stratified rocks of Cambridgeshire form part of the great mass of secondary strata which extends in an unbroken line from the Yorkshire coast to that of Dorsetshire. In the tract of which Cambridgeshire forms a part, their general strike is nearly north-east and south-west, and as the beds dip gently towards the south-east (at angles which approach horizontality) the older strata lie to the north and west of the county and the newer ones to the south and east. To the north-west of a line drawn from near Littleport to Gamlingay the rocks mainly belong to the Jurassic system; to the southeast of that line to the Cretaceous System.
Complications are introduced by folding, unconformabilities, and the existence of outliers. An anticlinal fold brings up a considerable mass of Jurassic rocks in the neighbourhood of the hamlet of Upware. An important unconformity occurs at the base of the Cretaceous rocks, causing the lower Cretaceous rocks to rest upon different members of the Jurassic System, while a smaller unconformity occurs at the base of the Chalk.