Notices and Extracts from the Minutes of the Geological Society. 135 



g. — Section of a Well sunk at Streatham Common, in the County of Surrey. 

 By Mr. Thomas Yeats : in a Letter addressed to Brown Esq., Secre- 

 tary to the Westminster Fire-Office ; and by him communicated to the 

 Geological Society. [Read April 2d, 1824.] 



Sir, Streatham, December 19, 1823, 



Having had the superintendence of sinking a well on Streatham Common 

 to the depth of 100 feet, and of boring- from the bottom of the well to the 

 further depth of 1 85 feet, I herewith send you specimens of the various strata 

 found in the progress of the work. The total depth of 285 feet is the greatest 

 which has hitherto been pierced in this part of the country. 



The London clay is here of considerable thickness, commencing almost 

 immediately beneath the vegetable mould, and continuing to the depth of 

 180 feet, when it becomes strongly mixed with sand. The specimen of clay 

 from the depth of 200 feet contains many fragments of shell, which have been 

 broken exceedingly small by the auger. Of this clay I immersed considerable 

 quantities in water, in the hope of finding a perfect shell ; but without success. 

 From what I have observed in the present sinking, as well as in other parts 

 adjoining, this appears to me to be a stratum, nearly 30 feet thick, consisting 

 principally of oyster-shells. 



At the depth of 235 feet we pierced the spring, which has hitherto supplied 

 this place with hard water. Up to this point we experienced no difficulties, 

 but such as arose occasionally from hard substances, which we passed through 

 by using the punch instead of the auger. The stratum of variegated clay, at 

 the depth of 256 feet, was very troublesome ; since after drawing the rods for 

 the purpose of emptying the auger, it swelled again into the hole before they 

 could be lowered. The hard rock, at the depth of 265 feet, caused great delay, 

 the punch having been used three days before it could be perforated. 



In the course of this work very few shells were found : in fact, the small 

 quantity of earth brought up by the auger gave me no room to hope for 

 many. 



I am. Sir, 



Yours respectfully, 



Thomas Yeats. 



