larly those in the Upper Chalk. In the well-known quarry at Down End he was able to identify for the first time in the island the "Chalk with Marsupites." Except in unimportant particulars, the zonal divisions of the Cretaceous series of the mainland are continued throughout the Isle of Wight. The upper part of the Middle and the lower part of the Upper Chalk of North-West Norfolk were likewise studied by the same observer. The divisional line of the Middle and Upper Chalk is well shown in the cutting of the railway between Narboro' and Swaffham, near Broom Heath. A bed of hard crystalline rock seen here resembles chalk-rock in character and minute structure. It does not contain glauconite, but the commoner fossils of the chalk-rock occur in it. It marks the summit of the zone of Holaster planus in this locality, and is the most northerly point where a representative of true chalk-rock has been found. With regard to the continuation of the zone of Holaster planus northwards, Mr. Hill was able to confirm the observations of M. Barrois, tracing the zone through Great Bircham towards the coast. The results of his Norfolk work have been embodied in the Survey Memoir of Sheet 69. Maiden Bradley, near Warminster, and Shaftesbury were likewise visited. At the first-named place Mr. Hill inspected a quarry exposing the junction-beds of the chalk and Upper Greensand which differs from the well-known section at Rye Hill. The fossils from this locality have been carefully collected by a local observer under the direction of Mr. Jukes-Browne. In the neighbourhood of Shaftesbury Mr. Hill was fortunate enough to obtain sections in the upper part of the Upper Greensand which filled up a gap in our knowledge of the sequence in this locality. He also examined large quarries in the Upper Chalk near Croydon, and part of the cuttings of the new railway from Croydon to Epsom, taking detailed sections where necessary. He states his opinion that there yet remains a most interesting and important question for Cretaceous geologists, viz. the correlation of the Middle Chalk of Norfolk with that of Lincolnshire and Yorkshire. In the present state of our knowledge neither Mr. Jukes-Browne nor Mr. Hill himself can say whether the zones of Terebratulina gracilis or Holaster planus exist in Lincolnshire, or what horizon divides the Middle from the Upper Chalk. Mr. Lamplugh's examination of the coast-section of the Hastings Beds, while serving to show the general accuracy of the published geological map so far as the lithological boundaries are concerned, has thrown some doubt upon the identification of the clayey strata in certain instances. Thus it seems possible that the clay shown on the map as Wadhurst Clay, to the westward of Bexhill, may represent the same deposit as that which is shown as Fairlight Clay to the eastward of that place, a point of considerable importance if the question of water supply should arise in this At the present stage of the inquiry, however, any positive statement on the subject would be premature. area. PLEISTOCENE AND GLACIAL. South Wales.-The ground surveyed in South Wales last year, including as it did a large tract of the high plateau and a number of the valleys that traverse these uplands, has yielded results of no little interest in regard to the glaciation of that region. In reports of the Geological Survey for previous years the occurrence of ice-striæ has been recorded from parts of Monmouthshire and Glamorganshire. These markings have shown a remarkable persistence of trend from N.N.W. to S.S.E. Last year's work has greatly extended our acquaintance with the source and movements of the mass of ice by which the striation was produced. The composition of the Drift strikingly confirms the conclusions founded upon the striation. The dip-slopes of Old Red Sandstone, and especially the valleys traversing them, are more or less overspread with semi-angular débris of that rock. Though it is extremely difficult to find an exact limit to such material, Mr. Cantrill has obtained ample evidence that it is in the main of glacial origin, for it contains scratched stones, occupies positions where it could be neither talus nor river-gravel, and rises into characteristic mounds in the Tåf and other valleys. The total absence of any rock other than that which forms the southern slopes of the escarpment furnishes the proof that the ice had its source on that feature and not to the north of it. Not even by the low pass (1,400 feet) at the head of the Tâf did any ice cross, for, though Drift mounds occur in the pass, they appear to contain none of the cornstones and green sandstones which crop out in Glyn Tarell on its northern side. A sheet of boulder-clay extends from Hirwain to Glyn Neath. Although now much cut up by denudation, it has probably been almost continuous, and was certainly of great thickness. At Hirwain it has been piled at the foot of the Coal Measure escarpment, at a point where the ice hesitated, so to speak, whether to turn southwards down the Cynon or south-westwards down the Neath; and, as usual in such a situation, the mounds and ridges have no definite direction. Nearer to the Vale of Neath, on the other hand, they invariably trend to the south-west down the Vale, and thus follow the striæ. Though containing abundance of pebbly grit (Millstone Grit), limestone, and Old Red Sandstone, the matrix is a dense blue clay, derived from the Coal Measure shales. This deposit runs up to the foot of the escarpment, but is there, in at least one pre-glacial ravine, replaced by a boulderclay of purely local origin. It would seem, therefore, that the escarpment was large enough not only to deflect the Brecknock ice-flow, but to nourish an ice-sheet of its own-an inference which is confirmed by the fact that the Rhondda Valleys, which rise on the southern slope of the scarp, are totally devoid of limestone and Old Red Sandstone boulders, although they contain well-developed lacial deposits. It is no less certain that a short distance farther west the escarp ment was overidden by the Brecknock ice-sheet, for the Fforch-dwm Valley contains abundant detritus of Old Red Sandstone and Millstone Grit, with some limestone, although it lies wholly on the south side of the ridge. On the opposite side of the same part of the Vale of Neath striæ have already been noted at a high elevation on Graig Llwyd. It is clear, therefore, that the Vale was here filled to overflowing-a result not to be wondered at when the great gathering-ground above and the sudden contraction of the Vale at this point are taken into consideration. No less characteristic is the disposition of the Drift in the track of the glaciation leading by way of Coebren to the Dulais and Tawe valleys. Around and north of Ystrad-fellte it consists almost exclusively of Old Red Sandstone, but westwards and southwards it gathers limestone and pebbly grit in abundance, and the matrix, as it passes over the shales of the Millstone Grit, becomes a purplish and finally dark blue clay of the densest description. It is packed with scratched stones, and arranged in characteristic mounds and ridges, all trending south-westwards, and imposing that direction on the various streams which descend the southern slopes of the Millstone Grit. The deposit is frequently exposed to a depth of over fifty feet, and is everywhere devoid of stratification and gravel. The valley of the Perddyn was ignored by the ice-sheet. Throughout the region described the Drift is of the kind known as "till." For though in the Old Red Sandstone area it is gravelly, it is so only from the scarcity of clay in the underlying rock, and the water-worn and more or less stratified pebble-gravels of the country farther south are conspicuous by their absence. At the same time it may be noted that no striæ have been discovered in the southern part of the coalfield, nor in the secondary area south of it, while the Drift itself does not now, and apparently never did, reach the coast near Barry and Penarth. These facts seem to limit the greatest extent of the ice-sheet in this part of South Wales to a breadth of about thirty miles, measured from its birthplace in the direction of its flow, and to indicate that "till" was the material formed by the ice-sheet near its source, while mounds of pebble-gravel accumulated towards its margin. In glaciated districts an inland cliff of a certain height and steepness seems invariably to present a moraine-like arrangement of ridges and mounds at its foot. Numerous examples of this relation were met with. The material composing these ridges is purely local and angular, and but for its position might be attributed to talus. The material, however, now falling tends to fill up the hollows enclosed by the ridges, and thus to obliterate them. The ridges are frequently compound, and generally crescent-shaped in Cwms, but more or less rectilinear under straight precipices. This form indicates that they are the moraines of diminutive glaciers, but whether they came into existence after or during the existence of the ice-sheet there is nothing to show. In a particularly wellmarked example near Abergavenny, they seem to merge into mounds of Drift of the usual character. It is worth mentioning that the development of the ridges shows no connection with the aspect of the crag. As many face the sun as are sheltered from it. In the course of his work on the southern side of the coalfield Mr. Cantrill has noted pebble-gravel overspreading much of the ground west of the Ely Valley. Near Pendoylan it is disposed in irregular mounds, enclosing hollows, with either small lakes or deposits of peat. The gravel consists chiefly of Pennant, but contains also fragments of chalk-flints, the origin of which remains for future investigation. RECENT. The large sand-barrows at Merthyr Mawr, Newton, Sker, and Kenfig (coast of Glamorgan) are noted by Mr. Tiddeman as a feature of the district surveyed by him. In some places these dunes seem to have made no progress since the date of the last Ordnance Survey; in others they are still occasionally advancing. Thirteen years ago one house at the southern end of Kenfig was nearly buried in twenty-four hours, and the inhabitants had to be dug out. The old borough of Kenfig, of which a few foundations are still to be seen, had to be abandoned in the fifteenth century. It is the general opinion that the sand made great advances in the sixteenth century. Beneath the sand, where it has been blown off the original surface, Mr. Tiddeman has found many chips of flint, together with arrows, lanceheads, scrapers, awls, and disused flakes, and occasionally ancient pottery. A considerable number of flintchips and weapons has also been picked up elsewhere by Mr. Cantrill on the Old Red Sandstone moorlands. PRACTICAL APPLICATIONS OF GEOLOGY. The applications for assistance made personally and by letter at the office of the Geological Survey, 28 Jermyn Street, London, S.W., during 1897 have included the following subjects :-Water-supply and contamination, mineral waters, sites for houses, foundations, landslips, coalfields, lime and cement, building-stones, road-metal, materials for artificial pavements, bauxite, ironstone, fuller's earth, oil-shale, asbestos, slate, salt, gypsum, polishing materials, silicification. The field work of the Survey has been the means of making known the existence and distribution of various useful minerals. The diatomaceous clays of the Bann, for instance, which were first indicated in this way, have now become the source of a new Irish industry. As one of its duties in connection with the collection of information regarding water-supply the Geological Survey carefully collects and registers all available data regarding the sinking of wells, and now possesses a large mass of information on this subject, obtained from all parts of the country. During last year numerous records of well-sinkings and borings, as well as analyses of waters and rocks, have been added to this collection. Fifty-six such records have been presented by Mr. Whitaker. It is hoped to publish a series of memoirs, giving records of all known borings for each county in England and Wales. |