Page:Transactions of the Geological Society, 1st series, vol. 1.djvu/284

 at the following places in the counties of Dublin and Wicklow. On the western side of the granite, in a streamlet joining the Dodder, west of the glen above Ballinascorney; at Golden-hill, near the granite quarries; and at Kilranlegah; on the eastern side, at Killiney, at the southern extremity of the Scalp; at Tonelagee, near Aghavanagh to the eastward; and at the south-western side of Craghan Kinsbela. On the shore of Dublin bay, between Booterstown and Blackrock, a mass of compact limestone is visible within a few fathoms of the granite, but in the interval the rock is concealed.

Near Ballinascorney, on the western verge of the granitic mountains nearest to Dublin, rocks of the trap family occur; and from thence to the south-westward, along the borders of the counties of Wicklow and Kildare, various intermediate rocks between the granitic tract above mentioned, and the limestone of the flat country to the westward will be found. At Arklow-rock, on the south-eastern extremity of the county of Wicklow, columnar rocks of the trap family have been observed by Dr. Wollaston and the Rev. Dr. Brinkley.

The quarries in the more immediate neighbourhood of the city, afford many varieties of calcareous productions. The Calp of Mr. Kirwan, a variety of limestone, of which an excellent description and analysis have been published by Mr. Knox, is the prevailing rock. Brown-spar (Jameson) is found in veins at the quarries near Dolphinsbarn; and beds of magnesian limestone were observed by Mr. Stephens in the bed of the river Dodder, at Miltown, and at Classonsbridge, above that place. The petrifaction's, which abound in many parts of this limestone country, the Calp, and the beds of magnesia