14 GARDEN MANAGEMENT. 



shmglS; forms a desolate hillock, extending seventeen miles along the coast, 

 ■without herb, house, or tree, but with inner waters and beach. This 

 barren waste — the Chesil bank — connects the isle with the mainland. The 

 quarries, of which there are at least fifty, occupy the north side of the island. 

 The upper beds of the oolite are here of a sombre yellowish colour ; it is 

 burnt for chalk. The next bed is a whiter stone, more pleasing to the eye ; 

 it is the stone of which the portico of St. Paul's is built. In these quarries 

 we find examples of the gi-eat changes to which the globe has been subjected. 

 The stratum of building-stone contains organic debris exclusively marine. 

 Upon this stratum rests a bed of limestone, formed by lacustrine waters, and 

 again over this a bed of bluish substance, supposed to have been an ancient 

 vegetable soil, which the miners call the dirt-hed. Here are trees and tropical 

 plants silicified, the ruins of a forest resting on the ruins of an ocean. 

 The trunks of the trees are often standing erect ; they even seem to have 

 been petrified while growing. It is supposed that the region now occupied 

 by the narrow strait and the neighbouring coast, had been a sea, in the bed 

 of which the oolite deposits, which produce the stone, had accumulated ; 

 that the bed of the sea had been gradually raised, until it emerged into 

 light ; plants began to grow on the newly elevated soil, and their spoils have 

 formed the dirt-hed. This vegetable soil, with the trees which grew on its 

 free sm-face, was afterwards engulfed in the waters — not the bitter waters of 

 the ocean, but in the fresh waters of a lake at the mouth of some great 

 river. Time passes on, and an alluvial soil deposited by the river covers the 

 dirt-hed. At length, some great cou%-ulsion occurs, all the region is engulfed 

 anew, and thrown to the bottom of an abj'ss, where, after ages of successive 

 change, the isle of Portland has again risen out of the sea. 



31, VII. The Cretaceous, or Chalk formation, comprises gi'een sands, chalk, 

 marl, and flint, among its constituents. It is conspicuous in the eastern and 

 southern counties of England ; it is the base on which rests the great tertiary 

 deposits of the London basin and the Wealden clay, and spreads over wide areas 

 in France and Germany. 



32. If we traverse England in an easterly direction, from Yorkshire to the 

 extremity of Kent, a totally difi'erent outline characterizes the plains and 

 mountains, the colour of the rocks, and the character of the vegetation. 

 Long ridges, having the appearance of coasts, may be traced in the interior of 

 the country, with their rounded headlands, and capes heaped behind capes ; at 

 their foot stretch out undulating plains, richly wooded, clothed with herbage 

 or with golden crops of richest cereals. Occasionally valleys are hollowed out 

 without watercourses, the heights and downs on either hand, which seem to rise 

 and fall hke the sea after a tempest, their summits often more or less denuded, 

 their white and tempest-torn surface contrasting strangely with the red and 

 broken rocks with which they are sometimes surrounded. In Oxfordshire, the 

 Chiltem Hundred are hills presenting this aspect. These chalky hills were 

 formei'ly covered with beeches. In Hampshire, a small chalk hill may still be 

 seen at Selbome. from which flow two small courses — a fountain and a brook — 



