448 



PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Juiie 5, 



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:§ I 



O > 



§.2 3 



9 ai 



appears to have been greater towards the 

 N.E., and less towards the S.W. ; for whilst 

 it is probable that at Deptford the displace- 

 ment does not exceed 90 feet, at Greenwich 

 it is about 120 feet (see Section, fig. 6), and 

 in the Greenwich Marshes 1 60 feet ; the chalk 

 being 1 24 feet from the surface at Greenwich 

 Hospital ^, and 55 feet of London clay having 

 been pierced in the Marshes. 



South of New Cross, on the contrary, the 

 dislocation (which at Deptford produced six 

 faults) is reduced to a few undulations and 

 one fault. (See Section, fig. 6.) 



About a mile and a half south-east of this 

 line of disturbance, and parallel to it, there 

 ranges another hue of fault, a section of which 

 was formerly to be seen near the lane behind 

 Morden College, and near the Tiger's Head 

 at Lee. The effect of this dislocation is that 

 the London clay occupies all the low ground 

 drained by the Lee Stream, a position not due 

 to it by the dip of the strata, which does not 

 exceed 2°. There is evidence of the exist- 

 ence of faults near Elthara, Chiselhurst, and 

 Bromley. 



In the hollow of Tranquilvale is a recon- 

 struction of the strata which crop out in the 

 sides of the valley. This was well exposed 

 in the cutting east of the Blackheath Station. 



The section (fig. 7) exhibits the contor- 

 tions of part of this reconstruction, the un- 

 disturbed bed at the base being the ash- 

 coloured sand (No. 2) with ferruginous strings 

 and concretions. The fragments of shell are 

 derived from No. 4 ; the coloured clay and 

 greensand from No. 3. 



These contortions may be owing to glacial 

 action ; and there is evidence of action of the 

 same kind in the centre of Blackheath. It 

 is not impossible that the few feet of loam, 

 &c. which there lie on the pebble-bed may be 

 a reconstruction (if not the commencement) 

 of the London clay. 



All the low ground about the Lee Stream 



* The following series of beds were penetrated by 

 the well at Greenwich Hospital : alluvium, 10 feet ; 

 gravel (drift or " pebble-bed " ?), 35 feet ; black sand, 

 blue clay, and shelly rock (equivalent to No. 4), 9 feet ; 

 red clay, white sand, and green sand and pebbles 

 (No. 3), 12 feet ; sand (No. 2), 57 feet, resting on chalk. 



