OF THE BAGSHOT BEDS OF THE LONDON BASIN. 165 



or in part) the beds of the Middle Group. These sections will be 

 found to lie almost in a straight line (nearly parallel to the general 

 strike) with the outcrop of these beds three-quarters of a mile 

 north of Wellington College (section E). Their outcrop on the 

 northern flank of Caesar's Camp is half a mile north of this line, and 

 will be noticed in its proper place. 



Section X *. South side of BuII-BrooJv, near Red Lodge, 



a. Pebble-bed in situ, seen in the ditch near 



the corner of South Hill Park (300' O.D.) No. 3. 



b. Loam and stiff clay, passing down into 



green earthy sand Nos. 4 and 5. 



c. Pebble-bed No. 6. 



d. Green earthy sands and loams Nos. 7 and 8. 



e. Clay and loamy ferruginous sand (250' O.D.) Nos. 9 and 10. 

 /. Fine quartz sand No. 11. 



Bed d apparently thins out entirely in the hill, on the north flank 

 of which (N.E. of South Hill Park) only the clays appear to crop 

 out. The altitudes give us a total thickness of about 50 feet for the 

 group of beds which, on comparative lithological grounds, we can 

 assign with a pretty high degree of certainty to the Middle Group, 

 though the section is not sufficiently open to give us the several 

 thicknesses of the individual beds. 



The hill near the Deer Park, with a plentiful scattering of flint 

 pebbles on its summit, owes its fine timber-bearing capacity to the 

 clays of horizons N'os. 4 and 5, which are powerfully developed here 

 and in the section last and next to be described. There is a good 

 exposure of the Lower Sands, with thin seams of pipe-clay, in a 

 sand-pit at the northern foot of the Deer Park hill ; and on the 

 south side of this pit the base of the Middle Group is seen, overlain 

 by from 1 to 2 feet of the drift of the hill-slope (mixture of pebbles 

 and reconstructed clay). 



Section L. Mr. T. Lawrence^s Brick-field^ Sivinley, 



a. Upper Sands of Tower Hill (about 60') 



with a good fresh exposure of 20' in 



a new sand-pit (base 300' O.D.). 

 h. Loamy clay (a much-prized brick- 1 



material), passing down into a strong I Nos. 4 and 5. 



laminated clay (12' to 14') J 



c. Dark-green earthy sand full of flint i 



pebbles at the top ; proved beneath h\-^ fi f 8 

 in trial-holes, and cropping out at j " *^ * 

 the north end of the brickfield J 



d. Mixed clay and sand bed, exposed in a 1 



pit close to the tramway (base about I Nos. 9 and 10. 

 260'O.D.) J 



e. Fine quartz sand in the valley Nos. 11 and 12. 



* It is convenient to make the sections of this paper form a continuous 

 series with those of my last paper (Quart Journ. Geol. Soc. vol. xliii. August 

 1887). All the numerical references to the sectional order of the beds are 

 (as in the last paper) to the section on p. 494 of vol. xli. of the Quart. Journ. 

 Geol. Soc. 



