Correspondence — Mr. Alfred Tylor, 891 



coieieESiPOiTnDEisrczB- 



DISCOVERY OF A PLEISTOCENE FRESH-WATER DEPOSIT, WITH 

 SHELLS, AT HIGHBURY NEW PARK, NEAR STOKE NEWINGTON. 



Sir, — Some of your readers may be interested in the discovery 

 made to-day by me of fossil shells, of the ordinary Thames Valley 

 species, in the more eastern of the two brick-pits in Highbury New 

 Park. 



The older and more western of these pits has been open for 20 

 years ; but although it possessed well-marked and stratified beds of 

 deep purple clays containing much wood, almost in a recent condition, 

 yet no fossil shells have been discovered. The surface of the ground 

 at the western brick-pit is 120 feet above the Ordnance datum-line. 

 At a depth of 40 feet in this pit the yellow sands are well seen at 

 the present time, false-bedded, 10 feet in thickness, and in many 

 respects like the Cyrena-sands at Crayford, but, unfortunately, up to 

 the present time no fossils have been found there. The surface of 

 the ground at the newer and more eastern of the two pits in High- 

 bury New Park, containing the newly discovered shell-bed, is 102 

 feet above the Ordnance datum-line. The clay-bed, 2 feet thick, and 

 full of land and freshwater shells, accompanied by much wood, is 

 22 feet below the surface, and consequently 80 feet above the 

 Ordnance datum-line. There are also some shells in the reddish loam 

 or brick-earth, immediately above the clay, so that the Thames 

 Valley fossiliferous beds reach at this point to 85 feet above the 

 Datum. The London Clay surface is supposed to be 10 feet below 

 the shell-bed. 



At 750 yards to the north of this brick-pit the Hackney Brook 

 formerly flowed, at a height of 75 feet, on a bare surface of London 

 Clay. 



At 530 yards due west of this pit the ground in Highbury Park 

 is 142 feet high, and the London Clay reaches to within 5 feet of the 

 surface, and is covered with coarse gravel, without any brick-earth. 



The thick brick-earth series intercalated with gravel, sand, and 

 clay beds on the Highbury New Park, therefore, probably owes its 

 formation and preservation to the protecting influence of this high 

 escarpment of London Clay. I have shown the importance of these 

 escarpments, and their relation to the Thames Valley deposits, in 

 papers read before the Geological Society. 



Mr. R. Tate has kindly examined the fossils collected in the 

 Highbury New Park pit, and gives the following list and remarks : 

 *' Land Shells. — Helix rufescens, var. depressa, Succinea putris, 



Zua lubrica, Carychium minimum. 



Clausilia biplicata, 

 "Fresh-water Shells. — Limncea palustrts, Valvata piscinalis 



Flanorbis marginatuSy Fisidium ohtmale, 



,, spirorbis, „ pusillum. 



Valvata cristata^ Cyclas cornea, var. 



" The above assemblage of species suggests a shallow pool or a 

 slow running stream of slight depth, on the margins of which 



