1850.] DE LA CONDAMINE — DISLOCATIONS AT BLACKHEATH. 445 



Loam-pit Hill, ferruginous and concentric towards Charlton. In the 

 former locality there are traces of wood and leaves in the lower part 

 of the bed ; but its principal organic contents occur occasionally in 

 the upper part. At New Cross this consists of the alternation of 

 yellowish sand, dark clay, and shells, with concretions* containing 

 freshwater shells, described by Mr. Warburton in 1845. In the 

 brickfield S. E. of the Naval School, the same beds appear, con- 

 taining — 



*Cyrena cuneiformis, Fer. *Buccinum. 



*Ostrea edulina, Sow. *Melanopsis ancillaroides ?, Desk. 



* Bellovacina, Lamh. Calyptrsea trochiformis, Lamk. 



elegans, Desk. *Rissoa. 



*Modiola elegans, Sow. Fragments of fish-bone. 



Unio Solandri, Soiv. *Wood. 



Paludina Desnoyersi, Desh. Traces of seeds. 

 *Ceritliium crenatulatum, Desh. 



At Lee, where the bed is twenty-five feet thick, the upper part 

 contains patches of shells, mostly crushed, but sometimes beautifully 

 preserved, and retaining even the colour when first exposed. Of the 

 fossils which I have found here, eight are identical with those in the 

 preceding listf ; the rest are — 



Potamides variabilis, Desh. Fusus. 



Melania inquinata, Defr. Teredo. 



Neritina pisiformis, Fer, Teeth of Lamna contortidens, Agass. 



Natica. 



This bed has suffered much irregular denudation before the de- 

 position of No. 6. At one spot (near the turnpike at Charlton) it 

 has been entirely swept away. (See fig. 2.) On Blackheath an insu- 



g Fig. 2. — Section at New Charlton. ^ 



3 ;: _ , - -^ 4 



1, 1. Pebble bed (No. 6). 4, 4, Mottled clay, greensand and 



2. Striped sand and loam (No. 5). pebbles (No. 3). 



3, 3. Shell bed (No. 4). 5, 5. Ash-coloured sand (No. 2). 



lated portion of it retains its original thickness, while at the distance 

 of half a mile, only three feet have been spared. (See Map, fig. 1.) 

 It has suffered to the same extent at Bostall Hill. (See Table I. 

 p. 442.) 



No. 6 is an irregular bed of rolled flint pebbles and sand, with a 

 few pebbles of quartz ; sometimes it is entirely wanting |. At Loam- 

 pit Hill it is represented only by an occasional line of pebbles. At 

 New Cross it is from two to four feet thick. On Blackheath it swells 

 out to forty or fifty feet, frequently filling spaces once occupied by 

 No. 5. 



* Since the above was written, I have found this bed of concretions at New Peck- 

 ham, where a mass of Paludince and Cyrence is exposed in a brickfield, 

 t Viz. those marked with an asterisk. 



X Mr. Prestwich has called this " the Basement-bed of the London clay." 



2 I 2 



