20 B. M. Brydone — Further Notes on the Trimmmgham Chalks 



Another point is the pseudo - stratification of the clay roughly 

 parallel to the sides of the fissure. This point is not well brought 

 out by the photograph, in which it only appears by the light-coloured 

 band. It was, however, much more apparent to the eye, being more 

 or less marked all through the mass owing to slight variations in 

 colour of the difierent bands, a reproduction of which is hardly to 

 be expected by photography. Here again we have appearance* 

 strongly suggesting that a pseudo-stratified mass of clay has been 

 forced upwards into a cavity. 



Another point which is not clearly shown by the photographs, 

 is that the face presented by Fig. 4 was an almost plane surface 

 apparently representing a clean section through the bluff, the clay 

 and a homogeneous mass of grey chalk at the back. 



A fourth point which cannot, owing to the shadow, be distiaguished 

 at all in the photographs, is that there was a slender arch of chalk 

 not more than two feet thick extending over the clay pinnacle and 

 connecting the bluff with the chalk behind. I was only just able 

 to reach the arch and ascertain that Ostrea hmata occurred in it. 

 The seaward face of the bluff was at this time too steep to climb 

 with any comfort, and the highest chalk which could be reached, 

 from the beach was normal 0. limata chalk, which apparently 

 continued up to the point where the nature of the chalk was 

 completely obscured by dirt. 



Since the Spring of 1901 there has been steady denudation at this 

 point. Unfortunately I was not able to obtain any photographic 

 record until the Autumn of 1904, but the course of denudation in 

 the meanwhile may be summarized as follows : — 



1. The Original Bluff. 



The top of the bluff remained inaccessible and obscured by sand 

 for some time. It became gradually cleaner and more accessible, 

 but during 1901 I found nothing but 0. hmata chalk exposed. By 

 1902 the downwash of mud had practically ceased and the face of 

 the bluff had been considerably stepped, and it was gradually 

 revealed that the bluff was capped by a bed of grey chalk of a fairly 

 uniform thickness of two feet and with a perfectly clean-cut boundary 

 between it and the 0. hmata chalk. (As this grey chalk will be 

 referred to again later on, I take this opportunity of saying that its 

 appearance is sometimes only to be detected by the change in colour. 

 But, as a rule, it is separated from the 0. hmata chalk which is 

 invariably found beneath it by an exceedingly thin seam of fine 

 grit, containing scattered flint pebbles of various sizes up to that of 

 a good-sized potato. In places this seam swells out into a definite 

 bed as much as two inches thick containing small rolled pieces of 

 chalk. The presence of rolled flints has not to my knowledge been 

 before recorded in the English or, indeed, any Chalk. It throws an 

 important light on the time of consolidation of the flints, which 

 must have taken place in this case almost simultaneously with the 

 deposition of the Chalk in which they were formed.) The grey 

 chalk was plainly unconformable to the 0. hmata chalk below, 



