A HISTORY OF NORFOLK 



The strata or formations known in Norfolk may be grouped as 

 follows, the names in italics referring to those not exposed at the 

 surface : — 



Period. 



Recent to 

 Neolithic 



Pleistocene, 



Paleolithic 



and 



Glacial 



Pliocene 



Upper 

 Cretaceous 



Lower 



Cretaceous 



Jurassic 



Formation. 



Alluvium, including Submerged 

 Forest and Fen Beds . . . 



Blown Sand 

 Shingle Beaches 



Brickearth . , 

 Valley Gravel . 

 Marine Gravel and Clay 

 Plateau Gravel 

 Boulder Clay . 



Glacial Sand and Gravel 

 Glacial Loam and Marl 



Cromer Forest Bed . 

 Norwich Crag Series 



London Clay 

 Reading Beds 



Upper Chalk 

 Middle Chalk 



Lower Chalk 

 Red Chalk . 

 Gault . . 



'Carstonc 



»3 



:3s 



Snettisham Beds . 

 .Sandringham Beds 



Kimeridge Clay 



Corallian 

 Oxford Clay 



Character of the strata. 



Mud, silt, clay, peat, marl 



and gravel 



Clean sand 



Chiefly flint pebbles 



Loam and marl 



Sub-angular flint gravel 

 Shelly gravel and clay . 



Boulder gravel 



Chalky clay, with flints and 



erratics 



Shelly sand and gravel . 

 Loam, with boulders and marl 



Gravel, laminated clay and 

 peaty loam 



Shelly sand and gravel and 

 laminated clay .... 



Grey clay and sandy clay . . 

 Green sand and grey clay 



Soft chalk, with nodular flints 

 and paramoudras 



Hard chalk, with nodular and 

 tabular flints in upper part, 

 and marly seams .... 



Hard grey and white limestone 



Red limestone 



Grey marly clay .... 



Brown ferruginous sandstone 

 and grit 



Clay, with septarian nodules . 



Light-coloured sands and 

 flaggy sandstone .... 



Dark shale and clay, with no- 

 dules and bands of limestone 



Clay 



Clay, with septaria .... 



Approximate 

 thickness 

 in feet. 



1 to 75 

 up to 6o 

 up to 50 



up to 15 



up to 45 



up to 30 



I to 45 



I to 130 

 I to 70 

 1 to 35 



10 to 30 

 25 to 100 



310 



46 



about 800 



about 300 

 80 to 130 



4 

 30 to 60 



up to 40 

 o to 30 



up to 100 



thickness 



not 



proved 



The superficial extent of the various formations is depicted on the 

 accompanying map. 



At present no borings in Norfolk have penetrated the Jurassic 

 rocks. The deep boring at Norwich (see p. 7) touched the Gault, 



2 



