Notices respecting New Books. 433 



sents itself to the geologist, whilst investigating the coast of York- 

 shire, relates to the occurrence of any of the tertiary beds above the 

 chalk ; and Mr. Smith has stated, on his geological map of Yorkshire, 

 that crag shells occur in the neighbourhood of Pattrington. These I 

 have previously described, and cannot doubt that they belong to the 

 diluvial epoch. Professor Sedgwick, who examined the spot in 1821, 

 describes appearances on the north side of the harbour at Bridling- 

 ton, which he supposed to indicate the presence of some one of the 

 strata above the chalk. I have repeatedly searched, without success, 

 for these beds ; but in July, 1828, I found, sixty yards north of the 

 harbour, below the level of half tide, an enormous mass of dark shaly 

 clay, whose laminae seemed dipping to the south. It was several yards 

 in length and breadth, was surrounded by brown pebbly clay, and 

 contained a few fossils, amongst which were a peculiar ammonite j 

 the columnar joints of Pentac. Briareus, and what I believe to be a 

 form of Avicula insequivalvis. I was at first much disposed to think 

 this a portion of a tertiary stratum, and still am altogether at a loss 

 to explain the appearance of so enormous a mass of perishable clay, 

 having the appearance of lias, at such a distance from the nearest cliffs 

 of that stratum. I recommend this point for further observation. 

 The specimens of Pholas crispata washed ashore full of coherent sand, 

 prove nothing whatever on this subject : such dead shells are parti- 

 cularly liable to be filled with the matter on the bed of the sea ; and 

 the only remarkable circumstance in these specimens is, that the mat- 

 ter which they contain is unusually solidified. Excepting those im- 

 perfect indications, I have never heard of a single fact which would 

 authorise a belief that tertiary strata exist in Yorkshire." 



The description of the Flamborough Cliffs gives occasion to reflec- 

 tions on the origin of caves and the wasting effects of the sea. 



" The origin of many inland caverns in limestone is exceedingly 

 obscure. Though water flows through many of them, and by inces- 

 sant attrition smooths their surfaces, and modifies their forms, yet, 

 perhaps, we ought rather to believe that the cave, originally existing, 

 directed the course of the stream, than that water excavated the cave. 

 By the sea side it is otherwise ; the destructive action of the sea is 

 not doubtful ; the cliffs crumble before its salt vapours, and waste 

 away under its furious waves. One loosened stone beats down an- 

 other, and thus the soft parts are hollowed out, whilst the harder por- 

 tions jut into promontories, or stand naked in the water. If the soft 

 parts, exposed to the waves, be enclosed in firmer matter, caves and 

 arches are formed, which are afterwards liable only to slow altera- 

 tion : but if these yielding materials extend far in a horizontal direc- 

 tion, the cliff undergoes rapid diminution. These observations are of 

 general application. Projecting capes and headlands are usually 

 composed of firmly-compacted strata, whilst bays and estuaries com- 

 monly present less resisting materials. Between the north landing- 

 place and a more remarkable bay to the west, the prominent clifts are 

 one hundred and seventeen feet high, and mostly composed of chalk ; 

 but at both these bays that stratum sinks low, and is covered by a vast 

 accumulation of diluvium. These unsolid materials fall and waste 

 N. S. Vol. 9. No. 54. June 1831. 3 K away 



