The March number of The Geologist contains, I observe, a notice of the “Upper Ludlow Tilestones,” and the author invites descriptions of their equivalent beds in other districts. Now, so close are the resemblances, lithologically and palæontologically, between these deposits and those of Forfarshire, that they may be regarded as part of one and the same series. I have been induced, therefore, to throw together the following observations upon our northern Scottish system.

The rocks to which I refer occupy a narrow but extended trough-line along the central district of Forfarshire, commencing on the east near Montrose, and terminating at Babruddery and Rossie Den on the west. They trend in a south-westerly direction, across the river Tay, into Fifeshire at Parkhill, Newburgh, and along the northern slope of the Ochils towards Dunning and Tereagles in Perthshire. These tilestones, and the grey and red sandstones with which they are systematically associated, occupy the whole superficies of that well-known and beautiful tract of country which is bounded by the old crystalline rocks of the Grampians on the north, and by the later felspathio Ochil range on the south; and it includes the celebrated geological localities of Cavonylie, Glammis, Forfar, Kinnordie, Clashbennie, Babruddery, and Parkhill.