I. Introduction. The area to which attention is directed in the following pages lies in the north-eastern corner of Forfarshire, and forms part of the singularly flat table-land of the South-eastern Highlands. It is essentially a moorland district, much covered with peat and heather, and is drained by two rivers, the North Esk and the South Esk. The rocks of which the area is composed consist principally of gneisses and schists; these are clearly seen in the craggy sides of the valleys through which the two Esks and their tributaries flow. Boulders of these rocks may be noticed in the rough walls by the roadside as one drives up the glens, and their intensely crystalline aspect is a most striking feature. A brief visit to the crags and the flat-topped moorland speedily convinces the observer that this crystalline aspect is one of the chief characteristics of the district. It is proposed to show in the present communication that this area contains several masses of intrusive rock which are probably connected underground, and that the highly crystalline character of the surrounding schists is mainly the result of thermometamorphism. II. Distribution And Mode Of Occurrence Of The Igneous Rocks . The normal condition of the intrusive rock is that of a slightly foliated granite, with two micas; but there are considerable variations from this type, both as regards structure and composition, as will be seen from the detailed descriptions that follow. It is met with in masses which vary greatly in size, and