9. Limestone in thin strata, impregnated with ochre so as to be unfit for burning. |
10. Ferruginous marl, containing a great many madrepores and shells quite detached from the rock. |
11. The first quarry of limestone. |
12. The second quarry of limestone. In the limestone of these two quarries the strata although separated by no intervening substance are very perceptible, preserving an uniform direction. |
13. Several thin beds of limestone which are not worked. |
14. At the distance of three or four hundred yards from No. 12, the assemblage of strata begins, which forms what is called the Black rock, so called from the dark colour of the stone. A third quarry is worked here. This rock is less tinged with ochreous infiltrations than the test usually are: it contains a great many shells and entrochi, and in its cavities are found dog's-tooth spar, cubes of purple fluor, acicular crystals of sulphate of strontian, and of oxide of iron. Similar cavities occur in the rock of the preceding quarry. |
15. Many thin beds of limestone divided by clay, some being very full of shells and entrochi, and others having scarcely any traces of organic matter. Some of these strata from the number of shells they contain may be recognised again on the rising ground at the foot of Leigh Down near the village of Leigh, on the southern side of the Avon. |
Page:Transactions of the Geological Society, 1st series, vol. 4.djvu/209
