Page:Transactions of the Geological Society, 1st series, vol. 1.djvu/228

 argillaceous slate of a fine grain, disposed in this layers with a few speck; of silvery mica interspersed through the mass. Black stains, or impressions of vegetables, are seen on the natural joints of this rock. Above this, lies a stratum of several fathoms in thickness, of a bluish calcareous marl, with specks of mica, which has an earthy and friable texture, and contains imbedded nodules or kidneys of sulphuret of iron. Many of these nodules have undergone a partial decomposition, to which, no doubt, the existence of the principal ingredients of the spring is to be ascribed. The upper strata of the cliff are composed of a calcareous free stone, alternating with a coarse shelly limestone, accompanied by nodules or layers of chert or flint.”

“ As the same arrangement of rocks here observed prevails in several other parts of the Isle of Wight, and even along the coast of Hampshire, it is not improbable that other springs of a similar nature might be discovered. May not Alum Bay, which lied to the north of the Needles, have derived its name from a circumstance of this kind?”

“ On the road from Shorwell to Chale, the soil consists of a ferruginous sandstone, and chalybeate iridescent waters are to be seen in several places; To the east of Fresh-water Bay, not far from the place where the cliffs of chalk begin to make their appearance, there is a rivulet, the taste of which strongly indicates the presence of iron. At Blackgang Chine, a little to the N.W. of the aluminous chalybeate, is another ferruginous. stream running