NORWICH CRAG SERIES. 467 



by Prof. Prestwich in 1849.^ They have been subdivided by Mr. 

 Wood, jun., as follows : — 



2. Chillesford Clay. 



I. Chillesford Sand with Shell-bed. 



The Chillesford Sand consists of micaceous sand with a shelly 

 bed (not constant) ; this passes upwards into a bed of laminated 

 micaceous clay, the Chillesford Clay. The entire thickness is from 

 20 to 25 feet. 



At Chillesford the sands have yielded Cardiiim Greenland ic urn, Cv- 

 prina Islandica, Leda obhngoides, Nucula teftiiis, and Tdlina lata. From 

 other localities the strata correlated with the Chillesford Beds have 

 yielded also Astarte borealis, Tdlina obliqua, T. prdtenuis, Cardium 

 edule, Cypiina Islandica, Lucina borealis, Nucula Cobboldice, Mactra 

 ovalis, Mya truncata {■=. Mya bed of the Rev. O. Fisher), Purpura 

 crispata, Littorina littorea, etc. 



Mr. Wood observes that the Chillesford Clay varies from a dark 

 blue tenacious laminated clay to a loamy micaceous sand, more or 

 less interbedded with seams of laminated clay. At Chillesford the 

 clay contains impressions of shells, and it has yielded remains of 

 a Whale ; at Easton Bavent a number of Mollusca, and one 

 impression of a Leaf, have been obtained by Prof. Prestwich from 

 the clay. 



The section at Chillesford is as follows : — 



Feet 



/-u-ii f 1 r> 1 i Chillesford Clay 8 



Chillesford Beds chillesford Sand with Shell-bed ... 8 



Red Cras: 



Scrobicularia Crag 10 



Red Crag 10 



The upper shell-bed at Bramerton and the Chillesford Beds, 

 according to Mr. Wood, are marine ; while at Easton Bavent, 

 Burgh Kiln (near Aylsham), Coltishall, Horstead, Aldeby (Toft 

 Monks), the portions of the Norwich Crag Series which he 

 correlates with the Chillesford Beds are fluvio-marine in character. 

 The fossiliferous bed at Aldeby (Aldeby Beds) was first brought 

 into notice by INIr. C. B. Rose in 1865, who identified it as Norwich 

 Crag. It is, however, almost entirely owing to the labours of 

 Messrs. W. M. Crowfoot and E. T. Dowson that its fauna is known 

 to us.^ 



Beds of Clay, regarded as equivalent to the Chillesford Clay, occur at Mells 

 Wood, near Halesworth, and at Withersdale Cross, near Harleston. At Aldeby, 

 Surlingham, Hartford Bridges, near Norwich, South Walsham, Hoveton (near 

 Wroxham Railway Station), Coltishall, and Ludham, there are good "jambs" of 

 laminated clay,* from 3 to 18 feet in thickness ; and any one who visited these 



1 Prestwich, Q. J. v. 345, Q J. xxvii. 337. See also O. Fisher, O. J. xxii. 19 ; 

 Wood and Harmer, Introd. to Supp. to Crag Mollusca, 1S72, p. viii. See also 

 Rev. W. B. Clarke, T. G. S. (2), v. 359. 



2 Proc. Norwich Geol. Soc. i. 24, 81. 



^ The term "jam" or "jamb" is applied to any impersistent, and generally 

 lenticular mass of clay, marl, or brickearth — it is a bed "jammed between other 

 strata." 



