The High Plateau is a rather ill-defined region occupying the south-eastern portion of Brazil. It rises abruptly from the south-east coast but slopes off very gradually to the north and west. In consequence the rivers flowing north and west are of great length and importance in navigation. Those flowing south are useless for navigation though of great importance for water power. An interesting exceptional river is the Parahyba flowing east and parallel to the south-east coast-line curve. The geology of the whole region is essentially granite and gneiss with curiously metamorphosed quartzites and schists. The accompanying map was made by the writer during some explorations carried out over this region in 1919, and as some of the points studied and already published (1), (2) were new and surprising to geological science, the following general description is added.

During part of 1918 the writer investigated the Cannel Coal and other possible sources of oil, together with occurrences of free Petroleum in the Yorkshire, Durham, and Northumberland coalfields, and subsequently watched the Government borings for oil in Derbyshire. The main results of this work have already appeared in sundry Geological Survey Memoirs, but some general conclusions on the subject of Petroleum in England and the facts which suggested them are here put forward. The possible oil-bearing horizons are regarded as three in number: the Lower Carboniferous rocks of Derbyshire, the Coal Measures in various fields, and the Upper Jurassic or Lower Cretaceous strata of a part of the Sussex Weald. Before giving details, a few remarks on Petroleum in general are necessary.

The Permian Basal Sands in South Yorkshire and North-East Derbyshire are very inconstant in thickness and they are often absent or unexposed over wide areas. They evidently filled eroded hollows in the Carboniferous floor and it is interesting to note that they are usually best developed where the underlying Coal Measures are soft and essentially shaly in composition. In the region under discussion some sections show the Lower Permian Limestone resting directly on the basal sand with but a slightly arenaceous base. Such is the case at the well-exposed sections east of Frickley, 15 miles north-east of Sheffield and at Harthill, 10 miles south-east of Sheffield.

1. Submarine erosion off Holderness is a fact, as pointed out by Winn.

2. The rate is greatest between H. and L.W.M.'s.

3. Between L.W. and 20 feet it is much less rapid.

4. Below 20 feet it still further diminishes to the 30-ft. line; outside which it apparently dies away.

5. Groynes—taking the long view—are unfortunately only a temporary safeguard for this district of easily eroded clay.

The writer's sincere thanks are due to Mr. G. W. Lamplugh, F.R.S., for his very kind and keen interest in the work.

Last year, I published a theory of the structure of the South-West Highlands in which was included a short statement regarding the metamorphism of the district (1922, p. 92). It seems that movement and metamorphism in this particular region have been too closely contemporaneous to allow of a tectonist deriving much assistance, in the initial stages of his work, from a study of the metamorphic condition of the various rocks with which he has to deal. There is no suggestion anywhere of contrasted metamorphisms having been brought into contact as a result of thrusting. If, as I suppose, there have been great thrust-movements, these must, for the most part, have occurred before the conclusion of the metamorphic period.

The classification set forth in this paper is founded essentially on an examination of the junction-beds between the Silurian and the Devonian in the field. All the localities described have been studied personally by the writer, and in most cases the actual junction has been mapped on the 6-inch scale. The names of localities are taken from the 6-inch Ordnance Survey maps, the sheet number being quoted in each case.