120 H. B. Woodward — A " Greywether" at Baymater. 



tionary block of sandstone. The rock itself was purely siliceous, 

 and presented the familiar saccharoid aspect of a Wiltshire Grey- 

 wetlier. Clean sand was found here and there in hollows on the 

 surface of the stone, tending to prove that it had never been dis- 

 turbed by human agency. It had evidently found a natural resting- 

 place in the basement-portion of the Thames valley-gravel, close 

 upon its junction with the London Clay ; the lowest bed reached in 

 the cellar being " stiif loam." These facts I was enabled to observe 

 under the guidance of Mr. B. J. Capell (architect and surveyor). 



In like situations near the base of the river-gravel, Grey wethers 

 have been found in many parts of the Thames Valley. Prof. Morris 

 has noted their occurrence near Kew Bridge, and they have been 

 observed at Ealing, in the Brent Valley, in the excavations for the 

 Courts of Justice, and again at Ilford and Grays ; but as Mr. 

 Whitaker remarks the blocks occur somewhat rarely.^ Nowhere 

 else, so far as 1 am aware, has there been found in the Thames 

 Valley deposits, a block so large as the specimen now discovered at 

 Bayswater. 



The transport of the larger blocks met with in the Thames Valley 

 deposits has been attributed by Prof. Prestwich to river-ice, and to 

 floods that imparted a torrential character to the river.^ 



Referring to the Greywethers found at Grays, Prof. Morris 

 thought they "may have been originally derived from the Boulder- 

 clay " ; ^ and although Mr. Whitaker questions this explanation, 

 there is evidence to show that such blocks were dispersed during 

 the Glacial period over the country north of the Thames. 



It is well known that over the Chalk tracts of Buckinghamshire, 

 in the area between Princes Eisborough and Beaconsfield, there is a 

 considerable extent of brickearth with unworn flints, Greywethers, 

 and occasionally pudding-stone. The brickearth in some places near 

 Hampden and Bradenham is opened up for the sake of obtaining the 

 stone, which is broken up and shaped into small paving-blocks, 

 largely used at Aylesbury and other places. 



This brickearth is very closely associated with the Clay-with- 

 flints, and may be considered to be largely made up of the wreck of 

 Eocene strata commingled with accumulations of Clay-with-flints. 

 Somewhat similar beds occur on the Chalk tracts of the North 

 Downs, to which attention has recently been directed by Professor 

 Prestwich. 



In Soiith Buckinghamshire the brickearth in many places is 

 associated with gravel, and this is largely made up of subangular 

 flints (derived chiefly perhaps from subaerial accumulations), together 

 with pebbles of flint from the Eocene beds, and quartzites. These 

 deposits stretch into Hertfordshire, where we find patches of 

 Boulder-clay. In my notes (made when mapping portions of the 

 area in 1869) * I stated in reference to the Brickearth and Boulder- 



1 "Whitaker, Geology of London, vol. 1. pp. 330, 397, etc. 



2 Phil. Trans, vol. cliv. pt. 2, pp. 289, etc. ^ Qj-ol. Mag. 1867, p. 64. 



* See Whitaker, op. cit. pp. 288, 289 ; and Prestwich, Quart. Journ. Geol. Sec. 

 vol. X. pp. 123, etc. 



