490 
DR. HENRY WOODWARD ON EAST ANGLIAN GEOLOGY. 
These Septaria or Cement-stones were largely used in the manu- 
facture of Eoman, Portland, or Parker’s cement.* 
Passing over the other members of the Eocene series which are 
wanting in Norfolk, comprising: — 
The Lower Bagshot Beds, with their sands, loams, pipe-clay 
and beds of pebbles, 100 to 150 feet in thickness. 
The Middle Bagshot Beds, including the Barton Clay and the 
Bracklesham Beds. 
The Upper Bagshot Beds and The Headon Beds, all charac- 
teristic of the South and South-east coast. — We next come to The 
Pliocene Series (for the Miocene is also wanting in England). 
The English beds classed as Pliocene occur chiefly in Norfolk and 
Suffolk. 
The Pliocene period embraces : — 
The Cromer Forest-bed series. The Eed Crag series. 
The Norwich Crag series. The Coralline Crag series. 
1. The Coralline Crag. 
1. The Coralline Crag consists of yellow calcareous shelly sands, 
from 40 to 80 feet in thickness. 
The term “ coralline ,” refers to the abundant presence of the 
hard chitinous fronds of Bryozoa (commonly spoken of as “horny 
Corallines”), which are almost always present in the so-called 
Coralline Crag. Every one who has walked along the sea-shore will 
have noticed the delicate fronds of the “ Horn-wrack ” ( Flustra 
fuliacea) strewn upon the beach at times. This horny structure is 
easily seen to be composed of numbers of microscopic cells, and 
is in fact (like the Bryozoa of the “ Coralline Crag"), the empty 
composite skeleton ( zoarium ) or house, in which hundreds of minute 
polypes (or zooids ) once found a home. The mam mass of the 
Coralline Crag sketches from Aldborough in the north to 
Gedgrave in the south, embracing Orford, Sudbourne, &c. 
The Coralline Crag is well exposed in the neighbourhood of 
Alborough and Orford, and at Sutton, Pamsholt, Tattingstone, 
Iken, Sudbourne, Broom Hill, Gedgrave, Gomer, &c. ; the Mollusca 
of the Coralline Crag have a more southern facies than the Norwicli 
* Principal Components: Carb. Lime 64.00, Silica 17.75, Alumina 
6.76, Magnesia 0.50, Iron 6.00, Ox. Magnesia 1.00, Water 3X0 = 100. (Loss 
1 . 00 . 
