Page:Transactions of the Geological Society, 1st series, vol. 4.djvu/206

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of stratified yellow sandstone, forming what has been called an upfilling. In the fissures of this rock crystals of carbonate of lime are found, and crystals of sulphate of strontian, which often assume a radiated form. This sandstone, having sometimes the appearance of a breccia extends to Redland. It is probably spread over the surface of the siliceous iron-stone already described; and in such a position it seems to have been found on Kingsdown in digging the vaults of Portland Chapel. The sandstone was there less firmly agglutinated, and the sulphate of strontian occurred about 4 feet below the surface in large irregular balls weighing many pounds.[1] At Redland this sandstone and the strata upon which it rests are rather abruptly terminated, being covered by a limestone stratified horizontally in thin layers, containing ammonites, gryphites, and anomiæ in abundance, and agreeing in all its characters with the well known limestone called lyas. The lyas extends to Gotham, where some of the strata are remarkable for taking a beautiful polish, being known at Bristol by the name of the Cotham stone. This lyas burns to a brown lime which sets hard under water.

But to return to the limestone. I do not intend to describe in detail all the beds of it; but the following are what I thought best deserving of notice, from their commencement immediately below the coal down to the lowest in the series. The first part of the series is best observed on the northern bank of the river.

  1. A beautifully crystallized specimen from these excavations was presented to the Society by Mr. Cumberland. It was found together with many other masses of the same substance imbedded in yellow marl. On digging the excavation for some houses at Clifton, according to Mr. Cumberland, the following minerals were found, but it is not known in what bed the vein occurred to which they belonged. Crystals of galena with foliated sulphate of strontian upon a matrix of sulphate of barytes. Quartz crystals enveloping needles of sulphate of strontian. These excavations are now closed, and the ground being built upon the minerals can no longer be procured.