1852.] DE LA CONDAMINE REVERSED FAULT AT LEWISHAM. 193 



other parts of England, I have thought their occurrence in this 

 district worthy of remark, and as heing likely to elicit the attention 

 of other observers of our tertiary beds. 



In conclusion, I have to draw attention to the discovery of two 

 extinct molluscs (Helix ruderata and H. incarnata ?, see fig. 4) in 

 the Copford marls, — a fact of considerable importance in estimating 

 the relative age of this deposit ; and I would observe, that not the least 

 interesting phsenomenon of the Copford freshwater beds is the super- 

 position of an upper member of the local boulder-formation (bed 

 No. 1) on the shell-marl, which latter, with its subjacent clays, rests 

 on an earlier member of this formation, — conditions clearly pointing 

 out the age of the intercalated deposit. This seems to accord also 

 with an analogous geological phsenomenon in the cliffs of Eastern 

 Norfolk and in other localities, as noticed in Sir C. Lyell's * Manual 

 of Elementary Geology,' p. 127. 



2. On a Reversed Fault at Lewisham. 

 By the Rev. H. M. De la Condamine, A.M., F.G.S. 



A RECENT section on the northern slope of Loam-pit Hill exhibits 

 distinctly a small "reversed" fault in the lower tertiary strata; and 

 the comparative rarity of this phsenomenon appears to render it de- 

 sirable that its existence in this locality should be noticed*. 



Fig. 1 . — Section at Loam Pit Hill, showing the Reversed Fault. 

 Scale, 6 feet=l inch. 



N.N.w. 



S.S.E. 



1, London Clay. 2. Pebble Bed. 3. Striped Sand. 



The accompanying section (fig. 1) will show its precise character. 

 The average angle of fracture is 30° : the displacement 6 inches. Its 



* See an instance recorded by Messrs. Prestwich and Morris, Quart. Journ. 

 Geol. Soc. vol. ii. p. 402. 



