mi: GEOLOGIST, 



compiled For the Holmesdale Natural Eistory Club, al Reflate, by Mr, 

 Brewer, The work is in small octavo, and contains nearly 370 pages, and 

 two Large excellent folded maps one of the geology, the other botanical 

 provinces; and it will be useful to add, thai tin' geologioal map can be 

 purobased separately in sheet, case, or on pollers, En aooordanoe with 

 Mr. Salmon's plan, the county has been divided into nine districts or 

 divisions, for tin* purpose of more readily ascertaining the particular Loca- 

 lities of the plants. The geological map has been prepared and coloured 

 from one drawn by Mtr. Prestwieh, and we need nol say will consequently 

 be acceptable to all who are interested in the geology of the county. 

 The three principal groups of geologioal si rata are the Weaiden, the 

 Cretaceous, and the London Clay ; Reading ami Woolwich beds, Thanel 

 sands, and other Tertiary beds surmounting tin* Chalk. Here and there, 

 especially along tin* river-valleys, are aoouraulations of gravel and drift 

 deposits, The whole of the north-eastern division of the count} belongs 

 to the London Clay formation, and is comparatively Lowj and consequently 

 the various elevations on the north side, such as Denmark, Heme, and 

 Richmond hills, although of no great elevation, still command extensive 

 prospects. It also forms the hills running southward along tin* Kentish 

 border by New Cross. Forest Hill. Sydenham, and Norwood. It is 

 estimated thai in some situations the London Clay is nearly a thousand 

 feet thirk, but that that portion which extends into Surrey does nol exceed 

 5(H) or bOO feet. The principal feature of the northern district is again 

 tin* London Claw covered in places by tin* Bagshol sand. as in the vicinity 

 of Esher. The whole of the north-western division consists of London 

 Claw for the most part covered with the Bagshol sand, .and presenting a 

 poor, hungry, unimprovable soil, as at Bagshol heath itself, which lies within 

 this region. Large masses of the siliceous sandstone known as "grey 

 wethers" are found there. The entire eastern division is ocoupied by the 

 Cretaceous rocks, with the exception of a small portion of the Reading 



and Woolwich beds, and tin* Thanel sands, which occur to the east of 



Croydon. Tin* Chalk occupies a considerable* area, and forms a portion of 

 the North Downs. Tin* Upper (rreensand, or freestone, forms tin* loot of 

 tin* escarpment of tin* Downs, and extends from (lodstone by Merstham 

 and Reigate through tin* county into Hampshire. The central division is 

 principally occupied by tin* Chalk, bid its north-west angle shows London 

 Clay, winch at Ockham Heath and Send is covered with Bagshol sand; 

 and a narrow slip of tin* Woolwich and Reading beds runs along the 

 northern margin of the Chalk. The western division is principally occu- 

 pied by London Clay, but a narrow ridge of chalk, known as tin* " Hog's 

 back." runs almost the w hole length of tin* southern boundary, and at the 

 toot of w liieh the Cault and Upper Green sand crop out, The south-eastern 

 division is, with tin* exception of a narrow strip of Lower Crcensand on 

 tin* north, occupied by the Weald Clay — the Hastings sand appearing at the 



south-eastern corner. The southern division is equally divided between 

 the Crcensand and Weald Clay. Tin* principal stratum in tin* south- 

 western division is the Lower Crcensand. 



The following is a brief analysis of the distribution of the plants: — 

 The total number of species occurring is 117; the number confined to the 

 valley alluvium, 7; to tin* superficial gravels, L9j to the Bagshol sands, 9j 

 to the London clay, 14; to tin* Reading and Woolwich beds, 2; tathe 

 Chalk, 55: to the Upper Greensand and Cault, 5 ; and to the Lower Green- 

 sand, 88, 



