510 Clement Reid — Isle of Wight Tertiaries. 



undoubted members of this family hitherto discovered, are the 

 species made known by Volta^ and Baron de Zigno^ from the fish- 

 beds of Monte Bolca, near Verona. 



VII. — The Extent of the Hempstead Beds in the Isle of Wight. 

 By Clement Eeid, F.G.S. 

 (Communicated by permission of the Director- General of the Geological Survey.) 



OWING to the impossibility of making an accurate Survey of 

 many of the flatter and Drift-covered portions of England, in 

 the absence of sections, the light boring tools so extensively used 

 by the Geological Survey of Belgium have been experimentally 

 tried during the last few months in the Isle of Wight. The results 

 arrived at are of so much interest that the Director has requested me 

 to draw up this preliminary notice.^ 



The Hempstead Beds, which were thought to be confined to the 

 outlier at Hempstead Cliff and another of unknown extent in Parkhurst 

 Forest, prove to be much more important, indeed they occupy about 

 half the Tertiary area of the Isle of Wight. 



To find their limits series of borings were made, radiating in different 

 directions from the highest points in Parkhurst Forest. These proved 

 that the whole of the deposits there represented belong to the 

 lacustrine Middle and Lower Hempstead Beds, for there was no trace 

 anywhere of the Corhula or Ceritkium plicatum zones. The " White 

 Band " was met with in several places in the lower part of the 

 Forest, but the outcrop of the " Black Band " (the base of the 

 Hempstead Series) is a long distance away. It was found — with 

 abundance of its characteristic fossils — less than half a mile from 

 the Chalk, at Gunville, one mile west of Newport, and was traced 

 eastward through Newport to Brading, always parallel with the 

 Chalk, and dipping at high angles away from it. The northern limits 

 pass near Eyde, Wootton, Osborne, and across the Medina to Gurnard, 

 Newtown, and Hempstead. 



Though no Hempstead Beds seem previously to have been noticed 

 in the East Medina, they are very well represented there, and must 

 be nearly 200 feet thick. At Wootton there is a small outlier, over 

 20 feet thick, of the higher estuarine beds full of Cerithmm plicatum, 

 C. elegans, and Melania hiflata ; but I have not yet succeeded in 

 finding any relic of the Corhula Beds. Below this are mottled clays 

 with JJnio, etc., for about 60 feet, resting on thick sands, which in 

 the East Medina seem to represent the base of the Middle Hempstead 

 Beds. Beneath the sands is another series of mottled clays with 

 Paludina lenta and Cyrena semistriata. These are about 80 feet thick, 

 and have at their base the "Black Band." The Black Band and 

 shales immediately above are very fossiliferous at Newport and 



1 Volta, " Ittiolitologia Veronese," 1796, p. 251, pi. 61. 



^ A. de Zigno, " Annotazioni Paleontologiche," Mem. R. Istit. Veneto, vol. xx. 

 (1877), p. 452, pi. xvii. 



3 Full details will be given in the new editions of Mr. Bristow's " Geology of the 

 Isle of Wight," and of the Geological Map — which, however, cannot appear for 

 some months. 



