HAMSTEAD BEDS. 191 



Borings were therefore made, and the Black Band traced 

 inland ; with the result that this horizon has been identified in 

 many places, and over a wider area than any other part of the 

 Hamstead Series. 



Forbes' description of the Black Band at Hamstead is excellent, 

 and will also apply to the inland sections. Unfortunately the 

 Nematura p^ipa bed at Hamstead has occasionally been confounded 

 with the Black Band, and. it is now probable that in a few of the 

 well-sections and trial borings the bed at first thought to be a 

 modified representative of the Black Band is really the Nematura 

 ■pupa bed about 30 feet higher. 



In the trial-borings the difference between the Black Band 

 and the clays lying below and above It is even more marked than 

 on the coast. The Black Band is generally a brown clay or loam, 

 turning a sooty black after a few seconds exposure, in which 

 abundant seeds and fish-bones are found, but few shells except 

 Paludina lenta^ Mclanopsis carinata, and Unio. In it occasionally 

 occur small angular fragments of flint. 



The next marked zone is the Nematura pupa bed, nearly 

 30 feet above the Black Band. This is a bed of laminated slate- 

 coloured carbonaceous clay crowded with Ci/rena semistriata, 

 Nematura pupa, Bythinia conica, and Cyprids, and more rarely 

 yielding other species. On the coast it is the first bed that 

 yields Nematura pupa, but Inland this species perhaps ranges down 

 into the Black Band, though it is not always possible to distino;uish 

 these horizons In borings. Though recognised at many localities 

 this bed seems to be more variable than the Black Band. A few 

 feet underneath it there is generally a line of Melauia muricata. 



The Nematura pupa bed indicates slightly estuaiine conditions 

 of deposit, yielding Modiola and GcrWiium at several localities. It 

 is perhaps the best ho.izou in the Lower Hamstead Beds for 

 fossils, for not only are these exceptionally well preserved but 

 the fauna is also more varied than is usual In these freshwater 

 beds. The following is a list of the species obtained, but no doubt 

 it could be considerably increased : — 



Cyclas Bristovii. Melania muricata. 



Cyrena semistriata. Melanopsis carinata. 



Modiola Prestwichii. subcarinata, 



subulata. 



Bythinia conica. Neritina tristis. 



Cerithium elegans. Nematura pupa. 



sp. (like C. plicatum). Paludina lenta. 



Hydrobia Chasteli. Planorbis (small sp.). 

 Melania Forbesii. 



About 36 feet above the Nematura pupa bed and Q5 feet above 

 the Black Band occurs the White Band. This consists of oreen 

 clay in which are seams of white shell-marl. Though so con- 

 spicuous at the base of Hamstead and Bouldnor Cliffs, it is not 

 persistent, being only traceable as far as Parkhurst Forest. In 

 the East Medina it is apparently represented by a seam of fine 

 sand which, commencing near Newport, expands eastward till it 



