320 Geological Society : — 



and Cheshire an important series of Post-Glacial deposits which he 

 has studied for many years. The whole country to which his notes 

 refer was formerly covered with a mantle of low-level marine 

 Boulder-clay and sands, and the valleys of the Dee, Mersey, and 

 Eibble were at one time filled with these glacial deposits. 



These glacial beds have been much denuded, especially in the 

 valleys, where the rivers have cleared them out, in some cases, to the 

 bed rock. Most of this denudation occurred during a period of ele- 

 vation succeeding the deposition of the Low-level Boulder-clay. On 

 this eroded surface and in the eroded channels lie a series of Post- 

 glacial beds of a most interesting and extensive nature. They 

 consist of estuarine silt and Scrobicularia-d&y covered by extensive 

 peat-deposits, containing the stools of trees rooted into them. Upon 

 these lie, in some places, recent tidal silts, and on the coast margin 

 blown sand and sand dunes. The series of events represented by the 

 denudation of the Low-level Boulder-clay and the laying down of 

 these deposits is as follows : — 1st, elevation succeeding the glacial 

 period, during which time the Boulder-clay was deeply denuded in 

 the valleys. 2nd, subsidence to about the 25-feet contour, when 

 the estuarine silts and clays were laid down. 3rd, re- elevation, 

 representing most probably a continental connexion with the 

 British Isles, during which time the climate was milder than at 

 present, and big trees flourished where now they will not grow. 

 4th, subsidence to the present level, the submersion of the peat and 

 forest-beds, the laying down of tidal silt upon them, and the accumu- 

 lation of blown sand along the sea-margin extending to a con- 

 siderable distance in an inland direction. 



It was estimated, from a variety of considerations, that these 

 events, all posterior to the Glacial period, represent a lapse of time 

 of not less than 57,500 years allotted as follows : — 40,000 years for 

 the elevation succeeding the Glacial period measured by the denu- 

 dation of the Boulder-clay in the valleys, 15,000 years for the 

 accumulation of the estuarine silts, clays, peat, and forest beds, and 

 2,500 years for the blown sand. 



2. " Note on the Movement of Scree-Material." By Charles 

 Davison, Esq., M.A. 



The author noticed the frequent high angle of slope of screes, 

 and called attention to Canon Moseley's observations on the down- 

 ward creep of lead on the roof of Bristol Cathedral, and his 

 subsequent experiment, and stated his belief that stones free to 

 move on the surface of a scree must be affected in the same 

 manner. This he proved by experiments, the result of which he 

 described. 



These experiments showed that stones do move downwards, owing 

 to alternate contraction and expansion, the movements accompany- 

 ing or occurring a short time after tho change of temperature, that 



