GEOLOGY 



Essex possesses one mineral water which attained a temporary 

 reputation. This was at Hockley Spa, where a permanent spring issues 

 from the base of the Bagshot Sand. Here about sixty years ago an 

 endeavour was made ' to establish a Spa with pump-rooms, and a woman 

 was employed to dispense them, whose strong healthy appearance visitors 

 were led to believe was the result of the medicinal effects of the water,' 

 but ' the speculation proved a failure.' 1 Dr. A. B. Granville, writing in 

 1841, gives an account of the discovery of the mineral water, and states 

 that it contained sulphates of magnesia and lime, carbonate of lime, and 

 chloride of sodium. 1 



With the growth of population the supplies of water from shallow 

 sources have in many cases become not only inadequate, but also con- 

 taminated ; and even when the supply remains sufficient for a small 

 country village the danger from pollution is great, especially if any 

 serious illness arises. 



The whole aspect of Essex appears geologically to be one of some- 

 what sluggish repose despite the constant waste of the ground by rain 

 and rivers and sea. The force of the breakers is however broken by the 

 shallow ground which borders a great part of Essex. 



Nevertheless geological action occasionally makes itself manifest in 

 a more startling manner. In 1884 a remarkable earthquake was felt 

 especially in the country between Colchester and the mouth of the 

 Blackwater ; and according to the detailed investigations made by 

 Prof. R. Meldola and Mr. W. White it was ' the most serious that 

 has happened in the British Islands for about four centuries.' They 

 state that the number of buildings damaged by the shock was between 

 1,200 and 1,300, including 20 churches and 11 chapels, and that the 

 main axis of damage had a general direction from north-east to south- 

 west, extending from Wivenhoe to Peldon. The effects produced may, in 

 their opinion, have resulted from the rupture of deep-seated rocks under 

 strain or pressure, such as the sudden production or extension of a line 

 of faulting ; and the localization of the damage was probably due to the 

 disturbance having originated under a clay area. 3 



i H. W. Bristow in Whitaker's Geo/egy of London, vol. i. p. 26 1. 



* The Sfai of England, vol. iii. p. 606. 



'Report on the East-Anglian Earthquake of April zznd, 1884,' Essex Field Club Special Memoirs, 

 vol. i. (London, 1885). 



