454 R. M. Brydone- — Zone of Offaster pilula 



specimens of 0. pilula having been observed in a thickness of 7 feet 

 of almost vertical chalk of most unpromising character. Above this 

 point there is only about 22 feet of chalk in situ, and it is very 

 unlikely that any representative of the upper belt of 0. pilula will 

 be identified on this side of the bay. A specimen of Boiirgueticrinus 

 Form 5 vras found a few feet below the belt with 0. pilula, a normal 

 position for it. 



2. West side. — The west side of Arish Mell, strictly speaking, runs 

 from the stream to the corner A, at which the vertical chalk comes to 

 an end; but each of the three small sloping promontories immediately 

 succeeding this corner contributes a little more to the thickness of 

 chalk passed over, and they are therefore included. 



It will be seen that from the corner A northwards the outline 

 divides itself naturally into three bays. The first runs up to a little 

 above the lowest beach level at corner B ; the second runs up to 

 approximately high-water mark at corner C, and its sides are more 

 or less wave-beaten the whole way ; and the third runs in a practically 

 straight line to an angle which marks, broadly speaking, the end of 

 the west side of Arish Mell, and thence again in a practically straight 

 line to the stream. About 10 feet east of this angle in the third bay 

 there is a low cascade (D) leading up to a deep hole some 4 feet above 

 the beach level. In winter a stream breaks out either from this 

 hole, running down the cascade, or at the foot of the cascade. The 

 cascade forms an excellent landmark, and starting from a flint 

 seam which crosses the cascade just below its top, and is the highest 

 that can be definitely identified, I measured the following section 

 seaward : — ,^ . 



ft. m. 

 Chalk 11 6 



Flint seam lining a south face extending west from 

 the cascade. 

 Chalk with A. quadratus at top ...... 4 



String of large flints. 

 Chalk 28 



Last flint seam north of angle C. 

 Chalk without flints embracing angle C .... 8 6 



Flint seam. 

 Chalk 74 



Stringy marl seam. 

 Chalk 16 6 



Thick marl seam. 

 Chalk forming ridge at angle B . . . . . . 2 6 



Thick marl seam. 

 Chalk ..26 



Strong parting. 

 Chalk 8 



Marl seam. , 

 Chalk 14 6 



Flint seam crossing recess. 

 Chalk with giant ossicle of Metopaster Parkinsoni . . 6 6 



Flint seam at end of clean chalk. 

 Chalk 17 9 



Strong marl seam. 

 Chalk 16 



Marl seam. 



Carried forivard . . 195 9 



I 



