In his book The Norfolk Landscape David Dymond writes (Alastair Press, 1990,25) ‘Laid down in a Cretaceous sea between 135 and 70 million years ago, the chalk consists primarily of the remains of once living organisms such as algae and foraminifera. It accumulated slowly, probably at the rate of one foot in 30,000 years. In spite of considerable later erosion, it is still up to 1400 feet thick and underlies the whole county east of the escarpment. Here on the ‘East Anglian Heights’ where the chalk is highest, we find rolling downland which is reminiscent of Wessex or the Yorkshire Wolds’. The East Anglian Heights is the section of England’s chalk escarpment between the Chiltern Hills and the Lincolnshire Wolds, then extending across the Humber Estuary to form the Yorkshire Wolds terminating at the majestic chalk cliffs of Flamborough Head. With this sedimentary strata being tilted the scarp slope of the escarpment always faces west. The East Anglian Heights form the least pronounced section of the Chalk Escarpment.
Throughout the Escarpment, but particularly significant in the East Anglian Heights, are the layers or nodules of flint found in the chalk rock. Dymond writes ‘Flint …. is the only widespread building stone found in East Anglia. Yet ironically this hard and indestructible stone, which can easily draw blood from the hand of a flint-knapper or mason, is derived from delicate sponges which once swayed on the bed of a Cretaceous sea’ (p.26). Flint is generally found in the middle and upper strata of chalk, this helping to determine why chalk in the lower strata is better for building stone (s.p.b.). Flint knapping is the skill of splitting flint nodules to expose a flat surface which then blackens as exposed to the elements. Knapped flint can often be seen in surviving old walls, bonded by thick, pliable lime mortar. In the later Middle Ages it was often incorporated into the external walling of wealthy East Anglian churches in panels to give strength and decoration.
(To be continued).