272 Notices of Memoirs — B. Mackintosh — 



occur in this layer. Subsequently the face of the cliff slowly shed 

 its frost-bitten fragments, and formed a talus of great thickness, on 

 the slope of which Neolithic men came and went. Then after some 

 500 years (as measured by the rate of formation of the talus), the 

 Eomano-British (or Brit- welsh), driven from their cities by invaders 

 (Picts or Saxon), lodged in the cave, and left their relics on the 

 sunny slope outside ; and these are covered by the fallen screes of 

 1200 years. Add these small sums of historic and pre-historic 

 years together; allow for the period of reindeer life in Yorkshire ; 

 measure out a time for the glacier's coming and going ; and add the 

 many years and ages whilst the great Pleistocene animals roamed 

 over the changing scene, and some notion will be gained of the 

 antiquity of man. To allow for the last uprise of Snowdon, for its 

 previous subsidence, and still earlier and higher elevation, some 

 200,000 years at least is required, when the glacial period came in. 

 If not before this period, certainly during some part of the time, 

 whilst England was continuous with the Continent, the mammoth 

 and man existed here together ; and the many great changes that 

 have occurred since Palseolithic man left his implements in lakes, 

 rivers, and caves, have required a large proportion of those 2000 

 centuries. 



II. — ^Kestjlts of Observations on the Eskers, Lake-basins, 

 AND Post-Glacial Eiver-courses of Cheshire, Shropshire, 

 Denbighshire, and Flintshire, with Eemarks on the 

 Sequence of Glacial Events in the N.W. of England 

 and Wales. By D. Mackintosh, F.G.S. 

 [Eead before tlie Chester Society of Natural Science, Feb. 3, 1876.] 



THE Chester Society of Natural Science, which was established 

 several years ago by the late Eev. Charles Kingsley, now 

 numbers between five and six hundred members. The above paper 

 is the second that has been printed. In it the author begins by 

 giving an account of the drifts between Chester, Gresford, and 

 Wrexham, with a particular reference to the sudden change of level 

 exhibited by the upper or brick-clay between Pulford and Gresford, 

 a change nearly 200 feet in vertical extent. The lower Boulder- 

 clay in this neighbourhood is either confined to patches or repre- 

 sented by an angular rocky rubble called '' rammel." The author 

 then goes on to describe the distribution of Eskers in Caernarvon- 

 shire, Glyn Ceiriog, upper valley of the Dee, around Gresford, 

 Gwersyllt, Cefn-y-bedd, Padeswood, Mold, Nannerch, Caerwys, 

 Flint, Oakmere (east side of Delamere Forest), Beeston Castle, 

 Combermere, Baschurch, Oswestry, and especially around Ellesmere. 

 The author then enters into a particular consideration of the causes 

 which determined the positions of eskers, laying great stress on the 

 influence of projecting rocks, etc. The curvilinear forms of esker 

 knolls, and especially of the enclosed hollows, he attributes to both 

 the depositing and denuding action of eddying tidal currents. A 

 more detailed account is then given of the high-level eskers on 

 Halkin mountain, which contain fragments of sea-shells, and one of 



