The trachytic flows from Nightingale probably extended at one time about a mile farther to the north than the present northern shore of Nightingale. This is evidenced by the trachytic agglomerate and trachyte seen on Middle. Following this there was an effusion of a hard, compact lava from a neck which exists on the latter island. The border of the neck is marked by a breccia. The dykes emanating from this lava are not seen on Nightingale, but some of the rocks which infest the channel between the islands are probably their eroded remains. The action of the sea on the mass of altered trachyte between Middle and Nightingale Islands has in the course of time cut a channel through. STOLTENHOFF It is not possible to land on this island, as it rises sheer from the sea to about 200 feet. It is flat-topped, and in area about 500 yards by 150 yards. The rock of which it is composed appears to be of a trachytic nature, and may be the northern limit of the flow’s from Nightingale, which have already been mentioned; it may, however, be a centre of activity, such as is described as existing on Middle Island. INACCESSIBLE ISLAND _Topography_ Eleven miles to the N.N.W. from Stoltenhoff is this island, which is the most northerly one of the group. In plan it is pear-shaped, being about 3 miles by 2½. In its general features it is a basin, being a great caldera, the south-east side of which has been blown out. A cone rises to about 1,500 feet towards the north-east of the depressed central area. The interior is broken country clothed in verdure, and on account of the high rim, which affords protection from the winds, would be suitable for human habitation. A stream winds through the interior, finally falling in a beautiful cascade to the beach at the north-east shore, where a landing is easily made if the wind is not from the north. [Illustration: Inaccessible Island] _Geology_ The central cone is a mass of scoriæ, and the section from here to the sea near the waterfall shows that there have been successive flows of basalt and trachyte. The high cliffs to the west of the landing are cut by a series of parallel dykes, which are an outstanding feature. ISLANDS OF THE MID-ATLANTIC OCEAN THE ST. PAUL’S ROCKS These lie just north of the equator, almost midway between Africa and Brazil. These rocks are almost unique in occurrence, for, as Charles Darwin remarks in his journal, “Its mineralogical constitution is not simple.... It is a remarkable fact that all the many small islands, lying far from any continent, with the exception of the Seychelles and this little point of rock, are composed either of coral or erupted matter.” The St. Paul’s Rocks are a group of eight or nine small rocky islands, the largest of which is only about 350 feet long by 150 feet wide. This island and the most northerly were the only ones where a landing was effected. [Illustration: Sketch Map of St Paul’s Rocks]