'262 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Jan. 23, 



hilly district, stretching from Croydon to beyond Gravesend, occu- 

 pied solely by this sandy and pebbly series reposing on a base of 

 chalk, and only in a very few cases showing a capping of the London 

 clay. The difficulty is, whether we are to consider any of the pecu- 

 liar fossiliferous, sandy or conglomerate beds of Woolwich, Bromley, 

 and adjacent districts as a fuller development of the basement stratum 

 of the London clay, or whether they all belong to a distinct and 

 underlying series. I am rather inclined, on structural evidence, to 

 the latter opinion ; nevertheless, on palseontological grounds it might 

 be presumed that a passage here exists between the two series. We 

 however yet feel the want of a few good sections to settle clearly this 

 point, to which I shall have occasion to revert more fully in another 

 part of this paper. 



At various points beneath the outlier of London clay at Shooter's 

 Hill are indications of the basement pebbly bed of the London clay ; 

 and some years since there seems to have been at Plumstead a deeper 

 and better section than any now existing ; for in some of the early 

 numbers of the ' Mineral Conchology,' Mr. Sowerby described a group 

 of shells from this locahty which bore a strong general resemblance 

 to those of the bed we are describing. The following is a hst of the 

 shells he enumerates : — 



Cardium Plumsteadiense, Sow. Fusns labiatus, Sow. sp. 



Calyptraea trochiformis, Lamk. Melania inquinata, Defr. 



Cerithium variabile, Desk. Neritina uuiplicata, Sow. 



Fusus latus, Sow. sp. Panopaea intermedia, Sow. 



costatus, Sow. Pectunculus Plumsteadiensis, Sow. 



■ gradatus, Soiv. sp. Planorbis (?) hemistoma, Sow. 



Mr. Morris informs me that he has here found casts apparently of 

 the Cyprina Moi'risii. 



From Mr. Sowerby' s description, I cannot learn whether the fos- 

 sils were all found in the same bed ; I should be uiclined to beheve 

 that they were not. The Flanorhis hemistoma, Neritina uniplicata, 

 and some species of Fusus, I have never found associated with the 

 PanopcBa intermedia and Cardium Plumsteadiense, so characteristic 

 of the basement bed of the London clay. Still, if this bed was here 

 accumulated under more flmdatile conditions, there would be no valid 

 objection to such an association of organic remains in this part of the 

 series. 



About six miles to the north-west of this spot, a cutting on the 

 Eastern Counties Railway, at Maryland Point, near Stratford-le-Bow, 

 exposed a very illustrative section. (See fig. 9.) 



Fig. 9. — Section near Stratford. 



w. E. 



'.',''■'■''.■:'.'' i','.'''.'..'/^--,":'-\'^i' Ochreous flint gravel. 



b. Brown clay (lower part of London clay?). 



Clayey green sand. 2. Yellow and ochreous sand. 3. Yel- 

 low and ochreous sand, with round flint pebbles and nu- 

 merous fossils. It occasionally forms calcareous concreted 



1 I L masses. 



3 rf, 1 to 3. Brown, dark grey and yellow clays. 4. Yellow sand 

 ^ I (5 feet), reposing upon a considerable thickness of mottled 

 J clays not exposed. 



u. urowu 



