284 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Feb. 18, 



ful fault which carries out of sight the marls below the " Three 

 Tiers," the " Three Tiers " themselves, and part of the micaceous 

 marls over them. 



4. Down Cliffs. — In consequence of the fault just mentioned, the 

 layer of small nodules already noticed in the Golden Cap (/, fig. 3) 

 is seen in Down Cliffs at a height of about 25 feet from the beach 

 (3, fig. 4). The overlying shell-containing mudstone (e, fig. 3), of 

 the hill to the westward, is here represented by an equal thickness 

 of hard shelly marl (2, fig. 4). The fault has therefore caused a 

 downthrow of about 200 feet, which great effect is not the result of 

 several small downthrows, but of one well-defined fracture. 



Sixty feet or so over the small nodules, a layer of massive sand- 

 stones projects from the face of the cliff. These are the Starfish- 

 stones (b, fig. 3, and t, fig. 4), so called from the beautiful specimens 

 of Ophioderma Egertoni, Broderip, collected from their under sur- 

 face. Beneath them is a layer of marl, rich in shells (c, fig. 3, and 

 Jc, fig. 4) ; and above them, and occasionally forming part of one 

 huge block, are large shaly nodules ; the entire series being identical 

 in character with their equivalents already mentioned in the Golden 

 Cap. As in that hill also, over these beds is a mass of shaly sands 

 with nodules (h, fig. 4), here attaining to a thickness of about 85 feet, 

 and capped by a band of blue, micaceous, siliceo- calcareous stone (g), 

 which yields most of the specimens of Ammonites margaritalus, 

 Montf., sp., that are collected here, and which I therefore term the 

 " Margaritatus-stone." Resting upon this layer is a bed of marl (/), 

 the grey or blue tint of which renders it a more prominent feature 

 in the section than its thickness of only 6 feet would lead one to 

 expect. This argillaceous deposit forms a remarkable break in the 

 series of sands, which recur over it (d, e) ; above, however, they are 

 less calcareous, quite as micaceous, and of a more decidedly brown 

 colour than those below. 



Over these upper sands, which are frequently indurated into 

 massive blocks of sandstone rather than into nodules (d), and which, 

 from the " Blue Band " upwards, measure about 70 feet in thick- 

 ness, is a mass of very micaceous grey marl or clay (c*), about 18 feet 

 in thickness. This is capped by a remarkable band of stone (1), the 

 lower portion of which is in great part a conglomerate, the pebbles 

 being imbedded in a more or less ferruginous matrix, with oolitic 

 granules. In places, however, this part of the bed assumes more the 

 appearance of the Marlstone of other districts ; it is separated from 

 the higher portion of the stone by a seam of iron- ore, seldom more 

 than an inch in thickness, but occasionally becoming thicker, and 

 then containing a remarkable assemblage of Mollusca amongst the 

 water-worn pebbles. This " Pleurotomaria-bed," as I have termed 

 it, and the underlying equivalent of the Marlstone appear not to be 

 persistent through the section, but the upper portion of the bed of 

 stone can be traced throughout. This higher part is composed of 

 thin bands of a hard, dense, almost chert-like limestone, separated 

 by thin laminae of yellow ochreous clay ; the whole, however, being 

 consolidated into one block. The entire thickness of the associated 



