Notices respecting Neio Books. 407 



We may here enumerate the strata downwards, from the surface, 

 with their greatest thickness in this area, as : — 



I. The Alluvium, or Recent River-deposits, about 15 feet 

 thick. 



II. Post-pliocene Tertiaries. 1. Old River-drift, Post-glacial : 



a. Brickearth or Loam, 30 feet; b. Gravel and sand, 20 feet; c. 

 Plateau Gravel of doubtful age, about 20 feet. 2. Surface-deposits 

 on the Chalk-tract : a. Brickearth and pebbly loam, about 30 feet ; 



b. Clay with flints, of doubtful age ; thin. 3. Glacial Drift : a. 

 Boulder-clay (" Upper Glacial "), about 40 feet ; b. Gravel, sand, 

 and clay, mterbedded (" Middle Glacial"), about 40 feet. 4. Pre- 

 glacial (?) Pebble- gravel, about 20 Feet. 



III. Eocene Tertiaries. 1. Bagshot Beds : a. Upper Bagshot 

 Sand, about 20 feet ; b. Bracklesham or Middle Bagshot Beds, about 

 10 feet ; c. Pebble-beds, about 30 feet, and Sand and loam, about 

 150 feet, together representing the Lower Bagshot Beds. 2. 

 Lower London Tertiaries: a. The London Clay, 450 feet; b. Old- 

 haven or Blackheath Beds, 50 feet; c. Woolwich and Reading 

 Beds, 90 feet ; d. Thanet Sand, 50 feet. 



IV. Cretaceous. 1. Chalk, 800 feet ; 2. Upper Greensand, about 

 30 feet ; 3. Gault, about 1G0 feet. 



The most noteworthy exposed sections of the different beds and 

 formations are carefully tabulated for each group, showing the 

 nature of the beds seen there, and their relative place in the series 

 to which they belong. 



Of the lowermost strata found by the deep boriug (1302 feet) at 

 Kentish Town, in 1853, the lowest 188 feet consisted of clays, 

 sands, sandstones, and conglomerates, mostly reddish, which have 

 puzzled geologists, but at all events indicate a deep-seated rauge of 

 older rocks covered by the Lower Cretaceous deposits iu a different 

 condition and of different structure from that of the Lower Green- 

 saud on the north and south of the London area. At Harwich a 

 boring, 1070 feet deep, also penetrated the Cretaceous rocks, and 

 pierced 44| feet into Lower Carboniferous (Posidonomya) rock. 

 In relation to these facts, Mr. Whitaker truly observes at p. 16 : — 



" One of the most striking pieces of theoretical geology, or of 

 philosophical inference from observed facts, is Mr. God win- Austen's 

 argument that the two exposures of the older rocks in the Ardennes 

 (Belgium) and in our own Mendip Hills (Somerset) are parts of 

 one great axis or line of elevation, and that they are most likely 

 connected underground by a hidden range of those older rock's 

 nearly aloug the valley of the Thames and the Wealden eleva- 

 tion — an important conclusion that was to a great extent verified 

 by the sinking of the Harwich well, and also by the doubtful nature 

 of the bottom beds in the Kentish-Town well. Although the fur- 

 ther argument, that veritable Coal-measures may occur along the 

 liues indicated has not yet passed out of the domain of inference, 

 and though, should beds occur, we cannot be certain they would 

 contain workable coal, yet geologists are fully justified in pointing 

 to the whole chain of reasoning as one that shows how pure science 



