149 



summit of Highgate to the Hertfordshire chalk downs, and from the 

 top of Shooter's Hill to those of Kent ; on the surface of which the 

 rivers once flowed. 2ndly, That these rivers have subsequently washed 

 away all that immense mass of materials which would be requisite 

 thus to reconstruct the surface ; and 3rdly, That having worn down 

 that surface into nearly its present form, the rivers perpetually shifted 

 their channels so as to distribute the gravel equally over the whole 

 plain of London, yet remained long enough in each channel to 

 lodge there deposits of this gravel 20 or 30 feet thick. 



A paper was also read entitled, "A few facts and observations as to 

 the power which running water exerts in removing heavy bodies," by 

 Matthew Culley, Esq., F.G.S., &c, in a letter to Roderick Impey 

 Murchison, Esq., Sec. G.S., F.R.S., &c. 



The heavy rains which fell during three days of August, 1827, 

 swelled to an unusual height the small rivulet called the College, 

 which flows at a moderate declivity from the eastern watershed of 

 the Cheviot hills, and caused that stream not only to transport 

 enormous accumulations of several thousand tons weight of gravel 

 and sand to the plain of the Till, but also to carry away a bridge then 

 in progress of building, some of the arch-stones of which, weighing 

 from | to f of a ton each, were propelled two miles down the rivulet. 



On the same occasion, the current tore away from the abutment oi 

 a mill-dam, a large block of greenstone-porphyry, weighing nearly 

 two tons, and transported the same to the distance of a quarter of a 

 mile. Instances are related as occurring repeatedly, in which from one 

 to three thousand tons of gravel are in like manner removed to 

 great distances in one day ; and the author asserts, that, whenever 

 400 or 500 cart-loads of this gravel are taken away for the repair of 

 roads, one moderate flood replaces the amount of loss with the same 

 quantity of rounded debris. 



Parallel cases of the power of water are stated to occur in the 

 Tweed, near Coldstream. 



June 19.— A. B.De Capel Brooke, Esq., of Lower Brooke Street ; 

 James Morrison, Esq., of Portland Place ; and Daniel Sharpe, Esq., 

 of New Ormond Street, — were elected Fellows of this Society. 



A paper "On the occurrence of agates in the dolomitic strata of 

 the new-red-sandstone formation in the Mendip Hills," by the Rev. 

 W. Buckland, D.D., V.P.G.S., F.R S., &c, Sec, was read. These 

 agates are ploughed out of the surface of the fields at Sandford, near 

 Banwell, and are nearly allied to the potatoe-stones, which abound in 

 the new-red-sandstone formation that surrounds the Mendip Hills. 

 Their prevailing colours are various shades of gray ; their internal 

 structure resembles that of the bird's-eye agate, presenting alternate 

 bands of chalcedony, jasper, and hornstone, disposed in irregular and 

 concentric curves : some specimens from Worle and Clevedon are of 

 the nature of fine jasper agates, and of a bright red colour. 



A shallow pit, from which the agates are extracted at Sandford, 

 piesents the following section. 



I. Yellow clay, mixed with magnesia and carbonate of 1 ^ ■ . 

 lime i / 



