IF. IT. HiuUeston — Crcechharrow in Purheck. 251 



the shell, represented by the brown calcite, is developed so obliquely, 

 that it is quite thick on one side and quite thin on the other side. 

 A section of this gives a shape like a horse-shoe, which evidently 

 belongs to the group of pisolites. 



4a. Very fine specimen of pisolitic limestone, quite suitable for 

 collections. Cuts well and takes a good polish. 



Without special illustration the above may be accepted as a brief 

 lithological description of the Creechbarrow limestone. Recently 

 some better specimens of univalves have been found, and tliese are 

 free from matrix ; but on the other hand they have suffered from 

 an incrusting process which has greatly afi"ected their original form. 

 The Paliidina appears to be a short variety of Paluclina media, and 

 the other univalve may possibly be a member of the Melaniadce. 



This limestone forms the summit of Creechbarrow, and it is 

 terminated towards the south by what may be deemed an escarpment 

 (see Fig. 4). We can follow it on the dip towards the north, though 

 its lateral extension east and west of the immediate summit is 

 certainly restricted, but the elongated shape of the summit ridge 

 is undoubtedly determined by this very hard rock. About 120 feet 

 N.N.E. of the summit, in the direction of the dip slope, we sank 

 another pit (No. 6) and came upon a very interesting section. The 

 hard nodular limestone is here found to form a very rough and 

 irregular surface, beneath a peculiar deposit which has a depth 

 of from 3 to 5 feet according to the inequalities of the limestone. 

 About 100 feet from this in a N.N.W. direction, and just within 

 the 600 feet contour, we found this same peculiar deposit, quite 

 6 feet thick, resting on the irregular surface of the tufaceous 

 limestone, hei'e apparently undergoing a softening process. 



The deposit on the Creechbarrow Limestone. — Of the many enigmas 

 which this curious hill presents to the puzzled geologist there are 

 none more difficult to solve than the true nature and origin of the 

 deposit which, from a geological point of view, is the highest in 

 the sequence, although sf> irregularly distributed that it has not 

 been indicated on the dip slope section (Fig. 3). The upper 

 portion of the deposit, in places, consists of a mass of rounded and 

 subangular flints in a muddy matrix, passing downwards into 

 a stiff yellow clay with much black oxide of manganese, and a variable 

 assortment of large and small flints, flint pebbles, and other stones, 

 disposed after the manner of Drift, At present I must be content 

 to state the facts about tliis deposit as I find them, without attempting 

 any explanation. It seems probable that in spite of its superficial 

 position this remarkable drift is really part of the Creechbarrow 

 series, and does not in any way represent the Plateau-gravel. 



We must now endeavour to trace the limestone (a) on the dip 

 slope to the point where it disappears. Omitting any indication 

 of the peculiar deposit mentioned above. Fig. 3 is a rough superficial 

 section from the summit of Creechbarrow (637 feet) to the sand-pit 

 about the 350 feet contour. 



The horizontal distance may be 1,150 feet. The northern spur 

 which we follow is in alignment with the lon2:er axis of the hill, 



