Page:Transactions of the Geological Society, 1st series, vol. 4.djvu/204

 singularly divided into regular cubical or rhomboidal concretions, the planes of which cut the planes of stratification at angles of about 45°. Some parts of this rock make a fine building stone, as may be seen in the docks, where the stonework is constructed of it. There is a number of small cavities in the sandstone filled with crystals of sulphate of strontian of a red or dull white colour, both colours appearing sometimes in the same crystal.

in the low ground, on which great part of Bristol is built, hollows occur in the surface of the sandstone, which are filled with alluvial matter, such as clay, peat, &c. The clay is of a blue colour, and from 10 to 20 feet thick. On digging the channel of the New River 12 or 14 feet below the surface, a bed of peat was found more than 2 feet thick. At the top of the peat were a number of oak trees, tolerably sound, all lying towards the north.

On rising from the vale of the Avon to the higher part of Bristol a siliceous iron-stone appears. Great part of Clifton is built upon this rock, which is also found in the country south of the Avon, forming that part of the hill above Ashton on which Sir H. Smith's house stands, and passing a little to the south-east of Belmont. It is in the cavities and veins of this rock that the beautiful quartz crystals, called Bristol stone, are found. They form 6-sided