152 TROF. J. PKESTWICH ON THE KELATION OF THE 



Fig, 1, Section from Oxfordshire to the coast of Suffolk. The length of tliis 

 section is about 140 miles. The dotted lines prolong the levels of 

 the Westleton Bed and Boulder-clay, and serve to indicate the 

 extent of denudation which has taken place since each of these epoclis 

 respectively. 



2. Section, about 50 miles long, passing from Hindhead through the Bag- 



shot district and across the Valley of the Thames, near Windsor, to 

 the borders of Hertfordshire. 



3. Section from the edge of the Weald across the Norwood Hills, the 



Thames at London, and the Tertiary hills north of London, to the 

 Valley of the Lea near Hatfield : distance about 40 miles. 



4. Section from the Valley of the Med way, near Tunbridge, by Cobham, 

 " near Eochester, across South Essex to the Brentwood group of hills : 



distance about 36 miles. 



Bailway- Cuttings. 



Fig. 5. Section of the Great Eastern Eailway, through Brentwood Common. 



This cutting was of greater depth ; only the upper 40 feet are represented 

 in the figure. The surface is 360 feet above O.D. 



A. Boulder-clay of a dark grey colour, containing fragments and small 

 blocks of chalk, sandstone, Jurassic rocks, angular flints, and flint- 

 pebbles, with a few specimens of Gryphoia incurva and a species of 

 large Oyster. Eastward, it passes into a sandy bluish -green clay with 

 flint-pebbles, and then into a brownish clay, roughly laminated and 

 without pebbles. It has a maximum thickness of 30 feet. 

 A'. Sand and gravel, consisting chiefly of flint-pebbles. The sand contains 

 thin subordinate layers of grey and brown clay. 



feet. 



(\. Fine white sand passing into bed No. 2 10 



", Ochreous and ferruginous, sandy, with some iron- 

 sandstone 4 



, The vipper part of this bed consists of a tough brown 

 laminated clay, with grains of green sand and a few 

 patches of white micaceous sand, passing down into 

 a massive argillaceous dark green sand, with some 

 I lighter seams. This bed contains numerous small 

 ' L'mgxdce, with casts of various bivalves in iron- 

 pyrites, teeth, and vertebrse of Shark and Carcha- 

 rodon, and fragments of wood pierced by Teredo ... 16 to 20 

 4. Fine light-yellowish sand, interstratified with thin 

 irregular seams of laminated dark-grey clay. 

 Traces of carbonaceous matter. No fossils. This 

 bed varies in thickness, resting on an uneven surface 

 V of the London Clay 4 to 12 



E. London Clay : dark grey with grains of green sand and concretions 

 of iron-pyrites. Only traces of fossils. 



Fig. 6. Section of the Black Notley Cutting on the branch line from Witliam 

 to Braintree. This fine and typical section was about half a mile in 

 length, and about 25 feet" deep in the centre. 



A. Boulder-clay containing numerous large angular flints and chalk-pebbles ; 

 it passes from dark brown to a whitish colour. 



A'. Boulder-clay gravel, very coarse and much contorted. It consists 

 chiefly of subangular flints, pebbles of flint and white quartz, of dark 

 quartzite and sandstones. The upper part is of a dull brownish-white 

 colour, whilst the lower part is dashed with ochreous, ferruginous, 

 and black seams and streaks, passing in places into a dark ferruginous 

 conglomerate 5 to 10 feet. 



