130 PKOP. J. PRESTWICH 0]^ THE EELITION" OE THE 



the Glacial and "Westleton Series are in some parts of Essex, 

 and how difficult, without the intervention of the Boulder-clay, 

 it sometimes is to distinguish between them. 



There is no group of sections in Essex more interesting than 

 those adjacent to Sudbury. The Chalk, the Lower Tertiary Beds, 

 together with Pre-Glacial, Glacial, and Post-Glacial Drifts, are there 

 exhibited in the same or in neighbouring pits. Since I visited 

 them they have been fully described by Mr. Whitaker, to whose 

 sections I would refer the reader *. The Pre-Glacial beds are ex- 

 posed at some of the pits on Balingdon Hill, where the Boulder-clay 

 reposes upon so irregular a surface that in some places it rests on 

 Pre-Glacial Sands, in others on some of the Tertiary strata, and in 

 others on the Chalk. 



On my first visit to these pits in 1845, I was inclined to believe 

 that the thick bed of sand and gravel under the Boulder-clay 

 belonged to the Crag ; but later, 1 was led to conclude, on the score 

 of position and composition, that it should be grouped with the 

 Westleton Beds. I found no fossils ; but Mr. Whitaker has since 

 then found traces of shells (broken) with unbroken specimens of 

 Purpura lapillus (var, crispatci) ; and in another pit he discovered a 

 bed of sandy ironstone, with casts of shells, of which 11 species 

 {op. cit.j). 31) were determined, though with doubt, by Mr. Etheridge. 

 With them were a few coprolites. On these grounds Mr. Whitaker 

 classes this bed with the Eed Crag, with a query. 



The Red Crag has not, however, been met with within a con- 

 siderable distance, and the fossils found are of a negative character. 

 The Purpura lapillus occurs in the Westleton Beds of Norfolk and 

 Sufiblk — as also species of Natica^ Cardium, Mytilus. Or the fossils 

 and the coprolites may have been derived from the Eed Crag ; for 

 the beds under the Westleton shingle are, as will be shown further 

 on, often greatly eroded. Or we may have here a remnant of Bed 

 Crag at the base of sands and gravel belonging to the Westleton Series. 



I express this opinion, however, with all reserve, though I 

 think it is confirmed, not only by the section at Burstall, but also 

 by one nine miles to the west of Sudbury, at a place called Burnt 

 House, near Stoke (fig. 6). In the pit there a very similar, but much 

 thicker bed of gravelly sands is seen resting on the Chalk, while 

 the Boulder-clay is worked in another pit just above. 



I found no fossils at this place ; but they have been since recorded 

 by the officers of the Survey, who give the following description of 

 the pit t : — 



feet. 



" Glacial Drift. White, grey, and yellow false-bedded sand, partly 

 coarse, partly fine, irregularly bedded, A mass of shells {Pur- 

 'pura lapillus) said to have been found at the bottom at one 

 spot (?Crag) 30 



? Drift or Red Crag. Bed of flints &c. (a piece of phosphatized 



bone) 1 to 2 



Chalk, bedded, with flints 30" 



* Mem. Geol. Survey. Geology of the N.W. part of Essex &c. pp. 14, 16, 



SI, 57 (1878) ; and ojj. cit. p. 132 (1885). 



t Mem. Geol. Survey. Geology of the N.W. part of Essex &c. p. 49 (1878). 



