160 



the natural drainage of the district, some other circumstances that 

 were noted previous to the occurrence may be mentioned. The 

 depth of the shingle on the shore, in making a sea-protecting wall 

 opposite the Parade walk, was ascertained to be 23 feet deep ; this 

 shingle rested on a bed of dark clay. Strong gales in previous 

 years had so scoured the shore as to disturb the base upon which 

 the sea-wall, flauking the main road at this end of the town, rested, 

 causing fractures in several places that required to be underset. 

 At low tide streams could be seen flowing from under the wall, and 

 large quantities of light-coloured sand covered the clay beds 

 extending along the shore. Further out to sea, at the lowest tides, 

 rocks of the Hythe bed, which succeed to the Sandgate bed, are 

 exposed to view. 



It was on these rocks, and during the gales alluded to, that 

 the ships Calypso and lieuveuue, in different years, foundered, and 

 their wrecks were broken up by explosives, and removed as a safe- 

 guard to the coasting navigatioi] under orders of the Admiralty.* 

 The scouring action of the gales may have been one element in the 

 mischief by weakening the so-called "Toe" of the land that 

 supported the weight above. After the experience with regard to 

 the soa-wall, groynes were added to hold and increase the deposit 

 of shingle. 



The N.iTTJKAL Dkain.vgk of the District. 



The Shorncliffe plateau uuder which Sandgate is placed, is 

 flanked by two valleys taking a uorthern course from the shore, 

 Horn Street Vale on the West, Encombe Vale on the East, crossing 

 obliquely the line of dip of the beds they cut through, and 

 carrying the water issuing from the T-yminge Vale and from the 

 surface above the Folkestone bed, as well as the springs issuing, on 

 the dip of the bed, from under it, onwards to the sea. The 

 Folkestone bed, composed of thick layers of the Greensand rock, 

 intercalated with softer sandy soil, is largely an absorbent bed, in 

 which from the intervening rock -layers, water may be irregularly 

 transmitted ; on the other hand the Sandgate bed, from its layers 

 of clay which appear to accumulate towards its base, has more a 

 retaining character, by which water, moistening the impervious 

 clay beds, converts them into argillaceous way-boards, upon which, 

 when sloping, superincumbent matter may slide. In the neigh- 

 bourhood of Canterbury, at St. Thomas' and Tyler Hills, where the 

 London clay-bed crops out with a variable gravel deposit of about 

 12 feet above, and the sandy Woolwic-li below it, the moisture 

 percolating through the upper deposit produces an irregular sloping 



* Some of the inhabitants of Sandgate attributed the landslip to the 

 remote influence of the vibration of 'hese explosions disturbing the soil of the 

 undercliff. 



