194 Dr. Bright on the Strata 



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, j* 



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 



* George Cumberland, Esq. of Bristol, has observed the same concretions, of which he 

 has presented to the Society a drawing. According to Mr. Cumberland the sandstone 

 alternates in its lower part with layers of a blue or greenish colour, and abounds with 

 sulphate of strontian, the masses of which contain in their cavities crystals of the same 

 substance of a lanceolate form and of an opake white colour. The masses are very fragile, 

 and fall to pieces on attempting to disengage the crystals by the hammer. Sulphate of 

 barytes is also found in the sandstone, but in small quantity. 



t In the alluvial matter the horns and teeth of deer, the grinders of the boar, and nuts 

 have been discovered. Blue phosphate of iron has also been found imbedded in a brown 

 clay. The trees, according to Mr. Cumberland, had all fallen towards the south-west. 

 Water worn pebbles and rounded blue flints were found at the bottom of the Canal near 

 to the dam. 



