17t» GEOLOGY OV THE ISLE OF WIGHT. 



Medina Cement Works, and Newport will be found in the 

 Appendix. Unfortunately the samples preserved are not suffi- 

 cient to prove the exact position of the base of the Hamstead 

 Beds, or to show the palseontological character of the different 

 ))arts of the Bembridge Marls. However, they show that the 

 Marls are about 120 feet thick, and that they consist of variously 

 coloured clays, as in other parts of the Island. 



The cliffs between Cowes and Gurnard are now much over- 

 grown and obscured by landslips, but the marine beds ovei-lying 

 the limestone seem to have been better exposed when Forbes 

 visited this part. He observes that : " At Gurnard Bay, whitish 

 marls, separated by a carbonaceous band, immediately surmount 

 the limestone, and then succeeds about a foot thick of blue clay 

 and shelly stone full of Cj/mice. This is surmounted by nearly 

 three feet of dark shaly clays containing oysters, Cijrcna 

 pulchra and ohovata, and Cerithium mutabile, a shell here much 

 more plentiful than I have observed it elsewhere. A well- 

 marked band of pale blue septarian stone succeeds ; then come 

 some 10 feet of shales and clays, with Cyrena ohtusa and 

 ohovata, Melania inuricata, and the Cerithium, which fossils re- 

 occur in clays and shales occasionally forming compact bands 

 to the summit of the cliff. At the point where this section was 

 noted the uj)per beds of the Bembridge limestone only are above 

 the shore." 



A short distance north of Gurnard Ledge, the upper part of the 

 Marls can be examined, for a small outlier of the Hamstead Beds 

 caps the hill. Here the shelly seam full of Hydrohia Chasteli, 

 Melania viaricata, and Melanopsis carinata is found 8 feet below 

 the Black Band. Further south, near Sticelett, the same seam is 

 again met with in the upper part of the cliff. 



The lower portion of the Bembridue Marls in Gurnard and 

 Thorncss Bays is of great interest, for it contains a thin seam of 

 insect-limct^tone, which adds very largely to our knowledge of 

 the land fauna of this period. Tins limestone was discovered 

 by Mr. E. J. A'Court Smith nearly thirty years ago, but no 

 account of it appears to have been published till Dr. Henry 

 , Woodward, recognising the great interest of the fauna, read notes 

 on it before the liritish Association and Geological Society in 

 1877.* Unfortunately a misvmderstanding of the relation of the 

 beds led to the " insect limestone '' being referred at first to the 

 Osborne Series and subsequently to the Bembridge Limestone. 

 Its true position, however, is in the lower part of the Bembridge 

 Marls, above the oyster bed. 



This part of the series was re-examined in May 1888 (by 

 Clement Reid) in company with Mr. Smith, who pointed out the 

 exact position of the insect limestone and showed a number of the 



* Rep. Brit. Assoc, for 1877, Trans, of Sections, p. 78, and Quart. Joitru. Geo/. 

 Soc, vol. XXXV. {>. 342, and pi. xiv. 



