RELATIONS TO OTHER BRITISH DEPOSITS. 53 



reached Cambridgeshire at a somewhat later date. The general 

 Physical phenomena of the period, which have been treated of by 

 Professor Judd and Mr TealP, point in the same direction, and 

 shew us that in the period of the deposition of these ironsands, a 

 transgressive wave of depression was slowly creeping northwards 

 from the south, so that the shore beds of the south are of some- 

 what older date than those further to the north. At the same 

 time I consider that the whole of this series of ironsands, pebble 

 beds, and coprolite beds of the western Neocomian outcrop 

 although not of exactly the same age, are so nearly synchronous 

 that they may fairly and, perhaps, in general work most advan- 

 tageously be treated as one bed. 



Now turning northwards from Upware and Cambridge we can 

 readily trace the Ironsand group in a series of exposures through 

 the Fen country up to the edge of the wash in the Hunstanton 

 cliffs; but for the details of the stratigraphy of this area we must 

 refer to the published work of Mr J. G. Harris Teall in the Sedg- 

 wick Prize Essay for 1873. 



Just beyond Upware, at Streatham, and at Ely, Haddenham, 

 Cottenham and near Rampton isolated patches of the Lower 

 Greensand have been left and are now more or less well exposed. 

 The Streatham bed was at one time worked for 'coprolites' (see 

 Teall's Essay, p. 24), when it yielded fossils all of the Upware type. 

 The 'derived' vertebrate fossils (Dakosaurus, &c.) were in a parti- 

 cularly good state of preservation at this place. But at the other 

 localities no nodule bed has been discovered and only the most 

 meagre traces of organic remains have been found; From the Neo- 

 comian of Ely specimens of Pleurotomaria (ornamented species); 

 Pecten orbicularis, Sow.; Corbis (probably the same as at Tealby); 

 Trigonia, sp. (large), are to be seen in the Woodwardian Museum. 



North of Ely a neck from the great gulf of sea and fen-level 

 stretches across to the east hiding all the solid geology under its 

 beds of peat, silt, and gravel. This extends for some fifteen miles 

 across (N. and S.), when the Lower Cretaceous sands again appear 

 at the surface around Downham Market in Norfolk. .At this place 

 some new features present themselves and good fossil evidences 

 may be gathered. 



1 Sodgwick Prize Essay. 



