PART II. CHAPTER XIV. 



173 



Recent and Newer Pliocene Strata. 



coast, but in some rare instances they penetrate inland to a dis- 

 tance of sixty miles from the sea, as at Bridgnorth, in Shrop- 

 shire.* They also rise occasionally to great heights, as at 

 Preston, in Lancashire, where they are 350 feet above the sea ; 

 and, what is still more remarkable, on a mountain called Moel 

 Tryfane, in Wales, near the Menai Straits, they attain an eleva- 

 tion of about 1400 feet.f In all these places they contain shells 

 indisputably of the same species as those which now people the 

 British seas ; and although, perhaps, on more accurate examina- 

 tion some slight intermixture of extinct testacea will appear, yet 

 the geologist will always refer them to the most modern tertiary 

 era. 



There are, moreover, a great many freshwater deposits scatter- 

 ed over England, which belong to the Newer Pliocene period, as 

 at North Cliff, in the county of York, where thirteen species of 

 British land and freshwater shells were found imbedded in the 

 same strata with the remains of the bison and mammoth.:]: In 

 like manner, at Cropthorne, in Worcestershire, on the banks of 

 the Avon, a tributary of the Severn, Mr. Strickland observed flu- 

 viatile and land shells, nearly all of recent species, with the bones 

 of an extinct kind of hippopotamus. Recent freshwater shells 

 also appear in beds of loam, together with bones of the deer 

 and mammoth, in the cliffs of the estuary of the Stour, in Suffolk. 

 Some writers have confounded these and similar fluviatile and 

 lacustrine strata, with the ancient alluviums which they term 

 diluvial. 



Older Pliocene strata in England — Crag. — There are some 

 few countries in Europe, as in the district between the Gironde 

 and the Pyrenees, in the south of France, or that between the 

 Alps, north of Vicenza, and the hills near Turin, in the north of 

 Italy, where fossiliferous strata representing all the three periods, 

 the Eocene, Miocene, and Older Pliocene, are present. But the 

 tertiary deposits of England are limited to the Eocene and the 

 Older and Newer Pliocene groups, the Miocene being wanting. 



It is chiefly in the eastern part of the county of Suffolk that a 

 deposit provincially named crag is seen in its most characteristic 

 form. This crag consists chiefly of a series of thin layers of 

 quartzose sand and comminuted shell, which rest sometimes on 

 chalk, sometimes on an Eocene tertiary formation, called the 

 *' London Clay." Mr. Charlesworth, whose opinion I have lately 

 had opportunities of confirming, has correctly stated that the 

 crag, in part of Suffolk, may be divided into two distinct masses, 



* See Murchison, Proceedings of Geol. Soc, vol. ii. p. 333. 

 t Proceedings of Geol. Soc, vol. i. p. 331., and vol. ii. p. 333. 

 t See Principles of Geology, Index, " Mammoth." 



