South-Western Part of Somersetshire. 371 



careous 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 con- 

 tained 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 cal- 

 careous spar of a vein in the quarries near Stringston. Thin strata 

 of a fibrous calcareous spar are frequently found between and pa-i- 

 rallel to the strata of slate clay and limestone. They are some-i 

 times abotit three inches ihick, and the direction of the fibres is 

 jalways 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 po- 

 sition, 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 di- 

 rection may be traced running between east and west, and dipping 

 in some places to the north and in others to the south. After fol- 

 lowing 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 be-i 

 tween two low hills 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 Biufe 



2 A 2 



