S3 Mr. Webster on the Strata of Hastings^ in Sussex. 



attention to the mineralogical nature of these cliffs. Many large blocks of it, 

 sometimes 10 or 12 feet long, lie on the shore in a very picturesque manner, 

 (See PI. VI, fig. 2, a, a,) and have evidently fallen from the top of the cliff: 

 they are broken up for paving and mending the roads, for which purposes they 

 prove an excellent material ; by their colour they are easily distinguished 

 from the common yellowish sandstone in which they are imbedded, and which 

 often remains firmly attached to them even after they have fallen. 



These blocks of grey calciferous stone frequently have their upper and 

 under surfaces distinctly mamillated, or formed of portions of spherical or 

 spheroidal figures. It has been supposed by some who have noticed these 

 fallen masses, that they have been worn into these forms by the action of the 

 sea : but this is evidently not the case ; since they are of the same shape 

 while still lying in the sandstone cliff in places where the sea could not have 

 reached them, the mamillary masses existing before the blocks were detached 

 from the yellow sandstone. Fig. 1 . (Plate VI.) represents a portion of this rock 

 viewed looking towards the sea ; and at 6, b, b, 6, are seen the above-men- 

 tioned blocks in their places. 



The sea does indeed frequently wear the surfaces of the blocks (and many 

 of them are seen so worn), but in a very different manner. By the friction of 

 the pebbles put in motion by the breakers, a number of hollows or concavities 

 are worked out, intersecting each other, and separated by sharp ridges. These, 

 (see c, fig. 2, Plate VI,) somewhat resemble casts taken from the mamillated 

 surfaces; but in the rocks worn by the pebbles there are angular projecting 

 ridges ; in the others, there are angular depressions. This mamillary ap- 

 pearance is too regular and constant to be owing to accident, and can be attri- 

 buted only to one of the varieties of crystalline action. The rock, when fresh 

 broken, has a peculiar glistening lustre, which reminded me of the fracture of 

 the crystallized sandstone of Fontainbleau, (the chaux carbonatee quartzifere 

 of Haiiy). Like that substance, the mamillated rock of Hastings is a sandstone 

 having a small quantity of carbonate of hme, which however, involving the 

 sand, has been sufficient to occasion the concretionary structure. It is however 

 remarkable, that the stone is composed of thin layers of sand parallel to the 

 bases of the mamillary projections; from which it would seem, that those 

 masses had at first been sand, and that the calcareous matter which obeyed 

 the crystalline influence had been introduced, or at least diffused through itj 

 subsequently. 



From the size of the masses in the cliff, they often, at first sight, resemble 

 beds alternating with the sandstone ; and it is only by a close examination that 

 their want of continuity and the very irregular nature of their distribution ap- 



