The basalt of Mullion Island, with the intercalated radiolarian chert, is well known from the descriptions of Teall and Howard Fox.1 It is a fine-grained minutely vesicular basalt, consisting mainly of radiating felspar laths and interstitial pale purplish-brown augite, and occurring in peculiar pillowy or bale-like masses. Owing to this curious structure and its intercalation with the chert the basalt is considered to be a submarine lava.

It is remarkable that in this district so accessible to geologists and visited by so many observers, the presence of these beds has not hitherto been noted. When it is understood that the point where the main area occurs is only between 8 and 9 kilometres from Cairo, and lies immediately to the north of the Petrified Forest—a place visited by nearly all the travellers who come to Cairo—one is apt to doubt whether geologists have ever seriously examined this district.

On the top of the cliff between Headon Hill and Widdick Chine, in Totland Bay, there is a Recent tufaceous deposit containing land and fresh-water shells. It extends along the cliff for nearly 350 yards in a north-easterly direction from the base of Headon Hill, and is about 60 feet above the sea-level.

It was first described by Mr. Joshua Trimmer, and subsequently by Professor Edward Forbes and Mr. H. W. Bristow. In the more recent memoir on the Isle of Wight the earlier descriptions are quoted, but the section is described as being then almost entirely overgrown.

Over twenty years ago, in 1882, I ventured to controvert a doctrine which was at the time maintained with remarkable unanimity by all geologists, and which was taught in all the current textbooks. It was that the ordinary ripple-mark of the seashore was formed by continuous water-currents of some kind; the current of water taking the place and performing the office of the current of wind which ripples the surface of sand-dunes.

After many months’ work at the Polyzoa in the British Museum, the author has been driven to the conclusion that the relationships of the Jurassic forms of the ‘genera’ Stomatopora and Proboscina have been misunderstood, and that consequently their present arrangement, as put forward in the British Museum Catalogue, is unsatisfactory.

On the rail to Biarritz the roots of the Pyrenees first appear at Dax, and are accompanied by those ophites and thermal springs which are special features of the entire chain. Vast deposits of salt, to whose first development I contributed, have added an important industry to the resources of this ancient capital of Aquœ Tarbelliœ, where the exact harness depicted on Roman medals is still characteristic of every cart. Beneath the existing ditch of the Roman fortifications rock-salt was accidentally discovered by a boring for mineral water, and the salt is now worked at three miles to the south-east, and is indicated by springs for a distance of seven miles. The deposit is known to be about 100 feet in thickness, but is of unknown depth beneath the existing borings.

Along the entire outskirts of both sides of the Pyrenees similar salt deposits abound, and they are often similarly accompanied by igneous rocks.

The salt formation of Dax is distinctly limited by the valley of the Adour, which here ceases to wander among the sands of the plain, and is suddenly and sharply diverted along a tectonic depression, running towards the Pyrenees in a south-west direction. Precisely parallel to this course, in the Cretaceous and Tertiary rocks of the Pyrenees, there runs, at a dozen miles to the north-west, the most remarkable example known of a tectonic valley sunk beneath the ocean. The Gouf de Capbreton, sinking with steep sides to over 3,000 feet beneath the even bottom of the Atlantic skirt, and affording evidence of igneous rocks in its surroundings and in the irregularities of its floor, is a perfect analogue of the neighbouring tectonic portion of the Adour.

The experimental work of this investigation was done by Grace D. Bradshaw in the chemical laboratory of Cornell College. The purpose was to determine whether the silica exists in a free condition or is in the form of a silicate; also to ascertain whether the iron is in the ferrous condition as carbonate or is in the form of ferric oxide. The rocks abound in many parts of Iowa, and belong to the Niagara formation. The stratified character even in a small section is apparent, and the layers differ somewhat in composition, as shown by the varying amounts of iron visible in different portions. The rocks are used as building stone to manufacture quicklime and in MacAdam paving.

The river Don has a remarkable semicircular course. Rising in the Middle Grits, west of Dunford Bridge, at 1,500 feet above O.D., it flows eastwards to Penistone (700′), where it makes a bend to the south-east, quickly deepens its valley to 500′, and at Wortley breaks through the great watershed (1000′) of the Grenoside and Wharncliffe grits. It then receives the Little Don, the Ewden, and the Loxley, on its right bank, and falls into the valley of the Sheaf at Sheffield (150'). The Don then makes a rectangular bend to the north-east, following the old valley of the Sheaf to Conisborough, receiving the Rother on its right bank at Rotherham (87′) and the Dearne on its left bank at Denaby (45′). It then traverses the Magnesian Limestone escarpment in a fine gorge, and continues past Donoaster in a north-easterly direction to Thorne, where it bends northward towards the Aire. It has, however, been artificially diverted by the Dutch River to the Ouse at Goole.

In studying the geological history of the rivers of the Don system, my attention was specially directed to the evidences of glacial action in the area, with the object of ascertaining whether glaciation had anything to do with the interesting diversions of the Don, Dearne, and Dove. Certain valleys in the area, also, attracted my attention as possessing abnormal features with respect to the present drainage of the district, and I began to inquire what their relations might be to an altered system of drainage during the Glacial Period. The present paper is an attempt to piece together the scattered glacial evidence, and to ascertain the effect that the advance of a glacier from the north and north-east would have on the drainage of this district, and how far the present valleys would help to explain the water-flow under such conditions.