494 DR. HENRY WOODWARD ON EAST ANGLIAN GEOLOGY. 
called the “White Crag” formation, but the upper part of the 
latter is also highly ferruginous. 
Norwich Crag. 
The Norwich Crag, so called by Lyell in 1839, is com- 
posed of a variable group of sands, pebbly-gravels, and laminated 
clays, with seams and patches of shells. These beds (in Norfolk) 
rest on the Chalk ; sometimes as at Thorpe pit near the Asylum, 
the Annelides of the Crag sea have bored into the eroded Chalk 
floor for several inches. 
4. Buff and red false-bedded sand and gravel, flint, pebbles, 
(iron-pan) seams of laminated clay sometimes cemented by iron. 
3. Laminated clay with seams of sand and gravel, “ Chillesford 
Clay.” 
2. White and brown sand with pebbly gravel and iron-stone 
nodules, sometimes called “ Fluvio-Marine-Crag.” 
1. Unworn and rolled flints called the “ Mammal if erous stone- 
led.” Shells are often absent. They are most frequent in beds 
one and two, to which the term “ Norwich Crag” has usually been 
restricted. 
Mammalian remains, no doubt derivative, occur in No 1 bed, as 
Elephas, Mastodon, Hippopotamus, Cervus, <$fc. ; among the more 
characteristic Mollusca may be mentioned : — 
Gasteropoda. 
Natica catena 
,, clausa 
Littorina littorea 
Conovidus pijramidalis 
Paludina media 
Purpura lapillus 
Trophon antiquus 
Turritella terebra 
Cerith turn tricinct um 
Scalaria groenlandica 
Lamellibranchiata. 
Tellina obliqua 
„ lata 
„ prcetenuis 
Cardium edule 
Astarte borealis 
„ compressa 
Mytilus edulis 
My a arena ria 
Mactra oval is 
„ suhtruncata 
Brachiopoda. 
Bhynclwnella psittacea 
ClRRIPEDI A. 
Balanus crenatus 
„ porcatus 
