Page:Transactions of the Geological Society, 1st series, vol. 3.djvu/376

 brownish yellow or cream colour, which is of different thicknesses, in some places extending so far into the interior of the stratum that the blue colour is nearly obliterated. I very rarely found organic remains in these beds.

§ 35. The other variety of the limestone is of a much darker colour, but is most particularly distinguished by the strong fetid smell it gives out when struck by the hammer, and when it is burning in the kilns. It is always in thicker strata than the other variety and abounds in organic remains, it is also very much penetrated by pyrites in many places. These fetid strata have much less the property of setting under water, and are best adapted for agricultural purposes, for which the other are very unfit. The quarries on the spot call the first blue lyas and building lime, the other black lyas and ground lime. They informed me that the building lime always lies above the ground lime, and in a quarry in the parish of St. Decuman's I saw a section where the upper strata were pointed out to me by the workmen as the best building lime, and they find the strata become less adapted for that purpose the lower they go. I found the middle beds slightly fetid, and the lowest more so and increasing in thickness.

§ 36. The fossils which are very numerous in the lyas series in most places, appear to be less abundant here. The cornu ammonis is the most common, and I found it several times above 18 inches in diameter. It frequently occurs in a flattened compressed state with the beautiful iridescence of the nacre preserved; a variety which Mr. Townsend considers peculiar to the lyas of this coast. The following are the few organic remains I had an opportunity of collecting:

Remains of a very finely striated Pecten or Lima.