Page:Transactions of the Geological Society, 1st series, vol. 2.djvu/55

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45
Dr. Berger on the Isle of Man

†† Amygdaloid.

Kaal-Farane and Cromwell' walk, two places that separate Scarlet point from the entrance of Pool-vash bay, present an unstratified bed of amygdaloid that overlies the limestone itself.

The basis of the amygdaloid is a wacke of an earthy texture, dull and of a greenish-grey colour, emitting a strong argillaceous smell when breathed upon. There are in the powder a few particles that effervesce with acids; the rock however fuses readily into a dark olive bead that is attracted by the magnet. There are in the basis nodules of lamellar calcareous spar, lined on their periphery with iron pyrites: the cavities they are imbedded in are smooth. When by the action of external agents the more tender nodules have been washed away, the rock partakes of the appearance of a slag, inasmuch as the basis is itself of a dirty red brown colour. The mean specific gravity from three specimens is 2.592.

††† Sandstone.

It occurs both under the form of fine granular and of conglomerate, of a red and grey-white colour, a little to the north of Peel town on the shore, and also on Langness isthmus. In the first place the strata run south-west and north-east, dipping north-west at 39°. At Langness, as we approach towards the south point of the isthmus, the conglomerate strata get higher and more thick-slaty. The materials entering into its composition are of a large size and much loosened. Along the Castle-town River, the sandstone overlies the limestone.