﻿1861.] 



DREW HASTINGS SAND. 



285 



VII. Conclusion. Liihological Characters of the Hastings Sand. 



To conclude : I should like to give a short summary of the gene- 

 ral character of the formation, and to call attention to those points 

 by a study of which we may get a fuller knowledge than we now 

 have of the sources of the material of which it is composed, and the 

 conditions of its deposit. 



Plainly divided (as the Wealden formation is, in spite of the ad- 

 mixture of the two substances to some extent through all its parts) 

 into clayey beds and sandy beds, we shall find in each of these certain 

 details that are worthy of notice. The clay is generally shaly, 

 not hard, but in soft fine laminae ; these are sometimes, though not 

 generally, separated by an accumulation of the cases of Cyprides : 

 the thinness of the flakes made Prof. E. Forbes give the substance 

 the very expressive name of " paper-shales." At some parts, how- 

 ever, there is a mere mass of clay without any stratification seen. 

 I believe it is always so when the clay is of that crimson-red colour, 

 ranging from that to purple, which occurs at some definite horizons ; 

 the origin of which, whether existing so in the rocks from which the 

 clay was derived, or acquired more lately, I should much like to hear 

 accounted for. The clay strata, as before said, are varied with oc- 

 casional bands of calcareous matter, either pure, as shelly limestone, 

 or mixed with a large proportion of sand, and making a calcareous 

 sandstone. Lastly, it contains irony matter, sometimes in the form 

 of concentrically flaking nodules of brown iron-ore, but more often 

 as layers of nodules of clay-ironstone. 



Of the sandy beds there is more to be said. The sand itself is 

 nearly always extremely fine, almost an impalpable sand. On this 

 account it bears itself somewhat in the same way that clay does as 

 regards the presence of water : instead of absorbing it like an ordinary 

 sand, it becomes a pasty mass that can be moulded like a very light 

 clay, and this though it contains no alumina. In appearance, as 

 well as to the touch, it a good deal resembles the "Loess" of the 

 Rhine. The roads that are made with the soft sandstone are in dry 

 weather thick in dust, but after a good deal of rain in a complete 

 slush of mud. A small proportion of clay mixed with this, as it is 

 in many of the loams that are met with in this formation, makes one 

 think the compound to be much more clayey than it really is. 

 Sometimes a coarser sand occurs, and this is found more useful for 

 building-purposes, from its having the quality of sharpness ; and less 

 frequently there are layers of pebbles in the sand, usually about the 

 size of a pea, but now and then as large as a walnut. I have found 

 this coarse deposit and the less than usually fine sand generally in 

 one of the beds of rock-sand. And here I would remark (but I do 

 not know if the fact is of any import) that these rock-beds in almost 

 every case of their occurrence underlie one of the beds of clay. 

 Hydrous peroxide of iron occurs in small quantities in the sand- 

 stone, generally in thin wavy flakes, sometimes more diffused, so as 



