Page:Transactions of the Geological Society, 1st series, vol. 3.djvu/379

 spar in their interior, running parallel to their shorter axis but not reaching the surface, and they are sometimes divided into septa which are coated with calcareous spar and sulphate of strontian. I was fortunate enough to break one of those masses which contained this last substance most beautifully crystallized, quite equal to many of the specimens brought from Sicily: the crystals are perfectly transparent and of a pale blue tint. It is not confined to these lenticular shaped masses, for I found it accompanying the calcareous spar of a vein in the quarries near Stringston. Thin strata of a fibrous calcareous spar are frequently found between and parallel to the strata of slate clay and limestone. They are sometimes about three inches thick, and the direction of the fibres is always perpendicular to the plane of the strata.

§ 39. About three miles and a half from the mouth of the Parret and at the termination of the low marsh land, the lyas strata first appear, rising above the sand in a highly inclined position, and nearly covering the low shore between high and low water mark. They are very much covered with sea-weed, and difficult of access from the very deep mud, but their general direction may be traced running between east and west, and dipping in some places to the north and in others to the south. After following this line of bearing a considerable way, they may be seen sweeping round in a great curve, and becoming perpendicular in their direction to the same strata not a furlong distant. They extend about a mile westward from their first rising, and then entirely disappear opposite a tract of marsh land lying between two low bills along the shore for about half a mile: at the western termination of this marsh they again appear in a highly inclined position, and a little farther west the shore begins to be bounded by cliffs, which continue without interruption to Blue