466 PHOCEEDIXGS OF THE GEOLOGICAL SOCIETY. [JunC 3, 



tien period be established, the reference of the pebble-beds in ques- 

 tion to that period would perhaps be the most probable hypothesis 

 that we could adopt. Nevertheless the great extent of country 

 which the range of Bagshot outliers show these beds, uncovered by 

 any other deposit, once to have occupied is more consonant with 

 what we should suppose would result from the desertion of an area 

 by a preexisting sea than from the occupation of it by a new one, 

 because such beach-rolled pebbles as these imply very shallow con- 

 ditions diuing their accumulation, and an advancing sea would form 

 other deposits as it progressed over the pebbles which had first accu- 

 mulated along its margin, and of these we find no trace ; whereas a 

 receding sea (such, for example, as that which had abeady deposited 

 the Lower Bagshot Sand) would accumulate successive fringes of peb- 

 bles along its margin as it receded, which would, as the sea abandoned 

 them, be left uncovered by any other deposit. Looking at the features 

 which obtain over the area dividing these pebble-beds from the E-ed 

 and Coralline Crag area of Suffolk, nothing is presented which would 

 connect itself with them in that direction. Should their accumulation, 

 therefore, have been due to an older Pliocene sea, that sea must, I sub- 

 mit, have been one occupying the south of England, and connecting 

 itself with the older Pliocene of jSTormandy mentioned by Sir Charles 

 Lyell *, or with the newer Miocene of Touraine, and not with any in 

 the direction of Suffolk. 



The pebble-beds in question occur in Essex on the Bagshot at 

 Brentwood, Shenfield, and "Warley (where they are in their greatest 

 thickness, approaching 20 feet), and at PQghbeach and Jack's Hill, 

 to the south-west of Epping. At IS'orton Heath, near Ongar, they 

 are present on a small exposure of Bagshot Sand which rises as a 

 boss through the Glacial Clay. They are also present on the Bagshot 

 at Frieming Church, and in the woods two miles north of it, in 

 Writtle Park Wood (two miles further east), at Stock, at Bille- 

 ricay, at Kelvedon Common, and near Bentley Mill — also between 

 Pilgrim's Hatch and South Weald, at Havering, and on Langdon 

 Hill. I also found slight traces of them on the Bagshot at Lambourn 

 End, near ChigweU, and at the opposite extremity of the county, on 

 the Bagshot at Kayleigh. A very similar bed of pebbles occurs on 

 Galleywood Common, near Chelmsford (where slight traces of the 

 base of the Bagshot Sand occur), the Glacial Clay lying close up 

 against them, but never underlying them. Their occurrence in 

 Middlesex is confined, so far as I knowf, to Hampstead Heath, 

 where traces of them are visible distributed over the surface of the 

 extreme summit of the Lower Bagshot outher there, their present 

 position there being apparently due to redeposit by the Postglacial 

 denudation ; but they are in decided contrast to the small patch of 

 fine Postglacial angular gravel hard by, on which the fir trees near 

 " the Spaniards" grow. I have not visited the Lower Bagshot outlier 

 on Sheppey ; but, according to a paper by !Mr. Weston, in the 10th 



* ' Manual,' 3rd ed. p. 166. 



t Mr. Pi'estwich informs me, however, that a bod of rolled flint pebbles caps 

 the Bagshot outlier of Harrow. 



