30 IRON SAND FORMATION. 



" 8. Clouts. 



" 9. Pity. 



" Advancing on these is a valley, where the mineral bed seems entirely 

 broken, and the sandstone sets on. At the distance of something more 

 than a mile, the ironstone is again seen. Another intervention of sand, 

 and then at low water when the tide goes out, the beds of ironstone 

 appear regularly on the shore. In taking the range northwardly, from the 

 bottom of Ashburnham Park, for twelve miles at least, the strata are 

 nearly the same, there being no material inequaUty of surface that does 

 not partake of sandstone, marl, ironstone, and sand again at the top. The 

 limestone and ironstone generally rise very near the surface, frequently 

 within three feet. The ironstone, at forty feet below the surface, is not 

 so good as nearer to it, being coarser, and working heavier in the furnace. 

 The very best of the veins are frequently intersected with stripes, the 

 tliickness of a quill, filled with a soft marly matter ; and the marl beds 

 which the iron lies in, wear a bluer appearance than where it is good. 

 The iron ore, of a dark colour and good quahty, is very strongly attracted 

 by the magnet *." 



2. Limestone and shale, in blue clay. 



The Hmestone of the iron sand perfectly resembles, both in appearance 

 and composition, the Sussex marble of the Weald, and like that deposit is 

 imbedded in a thick stratum of blue clay ; in fact, so striking is the re^- 

 semblance, that but for the remarkable difference observable in their 

 organic remains, the respective strata, in different parts of their course, 

 could scarcely be distinguished from each other. The limestone under 

 examination is of a light bluish grey, dark blue, yellowish, or reddish 

 brown colour. The upper layers are sphntery, and fall to pieces by ex- 

 posure to the air and moisture ; but the lower beds are extremely hard, 

 and form slabs, whose superficial measure frequently equals six or seven 

 feet. It is composed almost entirely of bivalve shells, imbedded in a cal- 

 careous cement, and is commonly of a sub-crystaUine structure. The shells 

 chiefly belong to a species of tellina; but they are in too mutilated a state 



* Youngs Agricultural Survey, 8vo. 1808. 



