The Cairnsmore of Fleet granite is the second in point of size of the four plutonic masses which penetrate the Lower Palaeozoic rocks of the Southern Uplands of Scotland, being exceeded in area only by that of the Criffel. Its outline is roughly oval and it measures 11 miles by 7 miles, the long axis trending N.E.—S.W., exactly parallel to the strike of the rocks of the Southern Uplands.

The region of Trelease Mill and Polkernogo, west of St. Keverne, forms one of the type outcrops of the Old Lizard Head Series north of the main Lizard gabbro. This small rather poorly exposed tract is distinguished not only because it has yielded the only recorded cordierite-bearing rocks among the Lizard schists but more particularly on account of the occurrence of the rarer rock types carrying anthophyllite together with abundant cordierite.

The deposit to be described is situated at Orleigh Court, in the parish of Buckland Brewer, some four miles west of south from Bideford, where it rests unconformably on the steeply dipping Upper Culm sandstones. Its greatest extent is from Orleigh Mill to Yeo Bridge, a distance of about three-quarters of a mile in a northwest to south-east direction, and from this line it extends to the south-west for an average distance of about one-third of a mile, only exceeding that amount to the south of the Higher Lodge. The only extensive section was seen in the Rookery, where 25 feet of material rest on a yellow clay. The highest point reached by the deposit, to the south-west of the Higher Lodge, is about 400 feet above O.D. From this point it slopes to the north-east, extending down to about the 100 ft. contour on the left bank of the River Yeo. It is possible that the north-eastern boundary does not reach such low levels as those indicated on the map, Text-fig. 1, for it is difficult to distinguish the original gravel from relatively recent hill wash; and, without a good deal of trenching or augering, it would not be possible to determine the boundary more closely than has been done in the present work.

During the years 1918–1931, there were 270 earthquakes with unusually deep foci, 167 in the Northern Hemisphere, 101 in the Southern, and two with epicentres on the equator. The normal depth of focus is assumed to be about 50 km. or ·008 of the earth's radius. The focal depths of the above earthquakes range from ·005 to ·090 of the earth's radius below the normal depth, or from 50 to 380 miles beneath the surface. Throughout this paper, the depth, when given in terms of the earth's radius, is referred to the normal depth; when given in miles, to the surface of the earth.

The peculiar tectonic structure called “boudinage” by Lohest (5, pp. 471–2), has recently been found in Unst, Shetland Islands, by Professor H. H. Read (8, pp. 134–8), who has also noted its occurrence in tie Durn Hill quartzites of Banffshire (9, p. 471).What would now be termed boudinage-structure was seen by Ramsay in North Wales, and was described in 1866 in these words (6, and. fig. 18): “In the great quarry west of the Ffestiniog and Trawsfynydd fault the cleavage dips from 45° to 50° north-west, the inclination of the beds being about 35° in the same direction, and a greenstone dyke runs through them between the cleavage-planes…, bulging and thinning off in a rapid succession of oval-shaped masses of 3 or 4 feet in length. Associated with it are quartz veins ccurring principally at the points between the separate bulgings of the greenstone.”