A HISTORY OF SURREY 



hence it is possible that the stream may have flowed from the eastward 

 across a tract extending over what is now the southern part of the 

 North Sea. The prevalence of the freshwater conditions must have 

 been of very long duration, since the thickness of the Weald Clay 

 alone in Surrey is estimated to range between 600 and 1,000 feet, 

 and to this must be added at least 600 or 700 feet more for the 

 Hastings Beds. 



The Weald Clay is interstratified here and there with thin bands of 

 sand and silt, with layers of limestone made up almost entirely of a fresh- 

 water univalve shell of the genus Paludina, and with nodular bands of 

 clay-ironstone. These harder strata generally give rise to slight ' features ' 

 or elevations of the surface, but they are rarely sufficiently thick to have 

 much effect upon the character of the soil, which is principally a heavy 

 clay. The farming of these ' strong ' lands has been most severely affected 

 by the depression in agriculture, with the result that the acreage under 

 the plough has largely decreased. 



The ironstone of the Wealden Beds was at one time extensively dug 

 and smelted, though not so largely in Surrey as in the neighbouring 

 counties of Kent and Sussex. An Act of 23 Elizabeth (1581) to restrict 

 the use of wood in these iron-works makes exemption of the woods 

 of ' Christopher Darrell, gentleman, in the parish of Newdegate, within 

 the weald of the countie of Surrie, which woods of the said Christopher 

 have heeretofore beene, and be by him preserved and coppised for the 

 use of his iron- works in these parts.' 1 



Although the great thickness of these Wealden freshwater deposits 

 implies the duration of the same conditions of deposition over the area 

 for a very long period, this must not be taken to denote that the land 

 remained for all the time at the same level. In fact we can only imagine 

 such an accumulation taking place where there was gradual subsidence 

 that kept pace with the rate of infilling of the basin. A similar balance 

 of conditions seems to be established at the present day at the mouths of 

 many large rivers, and it is supposed that the weight of the accumulated 

 sediments causes a gradual downward movement of the tract upon which 

 the mass is spread. 



However this may be, it is clear that towards the close of the 

 Wealden episode the waters of the sea began to gain ground, so that 

 in the uppermost portion of the Weald Clay in Surrey, as exhibited 

 recently in an enlargement of the railway-cutting between Redhill 

 and Earlswood, brackish-water shells make their appearance among the 

 freshwater fossils.* A further stage in the depression submerged the 

 whole of the Wealden area beneath the sea, and henceforward for a long 

 period marine conditions alone prevailed, though at first land probably 

 still existed not far distant to the northward and north-westward. The 

 submergence below sea-level seems to have taken place rather suddenly, 



' See Geol. Survey Memoir, < Geology of the Weald,' chap. xix. pp. 329-346, for infor- 

 mation regarding this extinct industry. 



* See also ' Geology of the Weald,' pp. no, 114. 



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