Creiff, Tillycoultry, Callander, Aberfoyle, Drymen, and other almost nameless places to the westward, marks the range of this breccia, leaving on the north side all those rocks distinguished by the name of primary, with many of those which bear the name of transition, and being followed to a certain distance southward by the usual series of sandstones and other secondary strata. In the middle of this secondary tract arises the hill of Kinnoul, forming the westernmost part of a long irregular ridge which extends from the north of Dundee to Perth, where it terminates. Through part of this course it exhibits an abrupt elevation to the south, subsiding northward by a more gentle declivity into the great plain of Stormont and Strathmore. Its visible boundary to the south is the alluvial plain of Gowrie, while to the north the red sandstone and that breccia which accompanies or precedes the sandstone, form the only rock for a distance of many miles, till we arrive at the mountain schistus. I am not acquainted with the connection of this ridge at its eastern end.
The height of Kinnoul, (that part of the ridge which I purpose to describe) is 600 feet above the plain of the Tay, and it occupies a length of a mile or thereabouts, exhibiting many abrupt faces in a state of constant ruin and degradation, which have thus formed a rapid slope at the feet of the precipices.
The rock itself contains many of the most remarkable varieties belonging to the tribe. It will be sufficient to give a general description of them, as no purpose could be served by an attempt to define rigidly either the spaces which they respectively occupy, or the order which they follow, circumstances which are subject to such variations as to obey no general rules. In some places a black basalt may be observed, but it is every where amorphous and approaches here and there to the most ordinary kinds of compact
