306 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



projecting buttress, and is continued thence to the shore at Walpen 

 Chine. The prominence of the mass which forms the eastern side of 

 Black-Gang Chine may be ascribed to a similar cause, the ruin between 

 the Chine and Rocken End being analogous to that on the east of 

 Whale's Chine above-mentioned. 



VII. Walpen and Ladder Sands and ClayX. — Nos. 24 and 25. 



24. The Crioceras nodules (23) are succeeded by (24) a dark green- 

 ish mud composed of sand and clay, altogether about 27? feet thick, 

 which is first visible on the east of Whale's Chine, and goes out below 

 the summit of Atherfield High Cliff. It contains nodules including 

 large Gryphsea and Ammonites Martini. 



25. The clay No. 25 has been the chief agent in the production of 

 the undercliff which extends from Walpen Chine to the top of the 

 cliff on the west of Brown's Down ; a natural subdivision and conspi- 

 cuous feature in the series of cliffs which form this section. Its top 

 first rises at the foot of the cliff, about 90 feet east of the opening of 

 Walpen Chine ; it is continued below the fissure at Ladder Chine, and 

 is well seen within Whale's Chine above the sandy beds 24; it is about 

 28 feet thick §, the lower part a brownish plastic clay, containing very 

 good specimens oi Panopcsa {My a) mandihula, with many other fos- 

 sils, discovered here by Capt. Ibbetson. The upper part, between 

 Walpen and Ladder Chines, is much mixed with sand, and contains 

 Pimia Robinaldina (d'Orb.), with several other bivalves, and a Den- 

 talium. 



Fossils of Nos. 24 and 25. 



24. fPanopaea elongata ? Venus (Vectensis). 



mandibula ?, Sow. Vegetable impressions, not determinable. 



Gryphsea sinuata. 



25. Panopsea mandibula ?, Soiv. Isocardia Neocomiensis 



plicata, Sow. (gu. ornata ? ?), d' Orb. 



fTellina inaequalis? Corbula striatula, Sow. 



fVenus Vectensis. fLima semisulcata ? 



near to parva. Gryphaea sinuata, Sow. 



Scaphites gigas ? Pinna Robinaldina. 



Nucula ? 



VIII. Upper Crioceras Ranges. — Nos. 26 to 34. 



These nodules can be traced from the shore beneath Walpen High 

 Cliff, through the lower chasm of Ladder Chine, crossing Whale's 

 Chine, and finally going out on the east of Atherfield High Cliff, 

 where the four ranges can be seen together, with occasionally a fifth. 

 The measures detailed in the Table were taken at that place. The 

 largest specimens of Crioceras came, I was informed, from No. 33, 



t This name, referring to local position, is better than that oi Fossiliferous Clay, 

 because all the clays west of Black-Gang Chine contain fossils ; and the sands also 

 are fossiliferous in many instances. 



§ I could not obtain a direct measurement of the thickness of these beds ; and 

 that which I have assigned to the clay is less than my guide supposed it to be. 

 The cut on the preceding page represents the general aspect of this part of the shore, 

 with the passage of this group through Whale Chine. 



