58 RELATIONS TO OTHER BRITISH DEPOSITS. 



conclusion that the Farringdon bed was of Precretaceous age, and 

 was possibly the representative of the Portlandians. Mr Sharpe, 

 at the other extreme, argued that they were of much later date, 

 later than any other British cretaceous rock. Again in 1807 Mr 

 Seeley came to' conclusions about the Potton sands similar to 

 those of Mr Godwin Austen with the Farriugdon beds ; but both 

 these authors seem to have given most attention to the vertebrate 

 fossils and to have believed that all these remains, together with 

 the rolled phosphatised casts of invertebrate species, were native 

 fossils proper to the deposit in which they occur. This entirely 

 destroys the value of their arguments, for we have seen that most 

 of these are really 'derived' fossils belonging properly to older 

 formations ; and when these are excluded the apparent conflict of 

 evidence disappears. For the indigenous species point uniformly, 

 not to a precretaceous or postcretaceous age, but to the higher 

 beds of the Lower Cretaceous series, i.e. the upper Neocomian or 

 Aptien. This has been very generally recognised during the last 

 few years. Mr Walker writes*: " The age of the bed [at Upware] is 

 the same as that of the deposits at Potton, Farringdon and 

 Godalraing, viz. upper Neocomian." 



Mr Teall refers all the Ironsand series and coprolite beds to 

 the very latest part of the Lower Greensand, posterior to the 

 Hythe and Sandgate series, and he believes and considers it of 

 importance that these beds pass up by simple gradation into the 

 gault, so that they might indeed be taken as the basement beds of 

 the gault. 



Mr Meyer and M. Barrels take them to be an extension of the 

 Godalming Pebble bed. 



I come to the conclusion that they are the representatives of 

 the Sandgate and Hythe beds of the South of England, including 

 the pebble bed, some of our " coprolite beds " presenting a very 

 close correspondence with the latter deposit. The upper part of 

 the Folkestone series is represented by the Downham Market bed, 

 and not by our Ironsand and phosphatic group, a physical break 

 separating the two series. 



1 In the Monograph of the Trigonice by Dr Lycett, Palaontographical Society, 

 Vol. XXIX., page 145. 



