262 SANDSTONES OF SCOTLAND. flagstones of Caithness, Cromarty., and Nairn ; and the upper, the yellow sandstones of Dura Den, re markable for the abundance of fish remains. In reference to the use of these sandstones for building purposes, Mr. Burnell observes as follows : The Dundee and Arbroath stones are sometimes employed in London, the former as an ordinary building stone, the latter principally as a flag-pave ment. The colour of the Dundee stone hitherto brought to London is rather disagreeable, for it is of a dark brown colour, or of a deep oxide of iron tint; but the stone is hard, and resists weather very satis factorily; in consequence of the colour, however, this material is never used in ornamental buildings. The Arbroath stone is of a denser character than that obtained from Dundee, but it is more decidedly ‘ flakey,’ to use a workman’s phrase, and it is there fore almost exclusively used for the purpose above mentioned. Occasionally, however, blocks of the largest dimensions, and of a very uniform character, are obtained from the Arbroath quarries. They are hard; they resist weather satisfactorily ; the stone is easily worked, and its colour (a light greenish grey) is far from being disagreeable. 1 were discovered by the late Mr. Hugh Miller, and referred to their true origin by Prof. Agassiz. The crustacean is known as Ptery- gotus Anglicus, Ag. ‘ Poissons fossiles,’ &e. 1 Ibid, supra cit. p. 260.
