been originally sands like those of Hampstead Heath by the presence in them of narrow bands rich in zircon, rutile, and the other heavy minerals which are so constantly present in the finer-grained arenaceous deposits of all ages. Such pleasant surprises as the recognition of a character like this increase our confidence in the theory which endeavours to explain the past by reference to the present, and refuses to admit the necessity of believing in the existence of rocks formed under physical conditions different from those which now prevail simply because there are some whose origin is still involved in mystery. A crystalline schist has been aptly compared to a palimpsest. Historical records of priceless value have often been obscured by the superposition of later writings; so it is with the records of the rocks. In the case of the schists the original characters have been so modified by folding, faulting, deformation, crystallisation,, and segregation that they have often become unrecognisable. But when the associated rocks have the composition of sediments we need have no hesitation in attributing the banded structure in some way to stratification, provided we clearly recognise that the order of succession and the relative thicknesses of the original beds cannot be ascertained by applying the principles which are valid in comparatively undisturbed regions. In studying the crystalline schists nothing, perhaps, strikes one more forcibly than the evidence of crystal-building in solid rocks. Chiastolite, staurolite, andalusite, garnet, albite, cordierite, micas of various kinds, and many other minerals have clearly been developed without anything like fusion having taken place. Traces of previous movements may not unfrequently be found in the arrangement of the inclusions, while the minerals themselves show no signs of deformation. Facts of this kind, when they occur, clearly indicate that the crystallisation was subsequent to the mechanical action. Nevertheless, it is probable that both phenomena were closely related, though not in all cases as cause and effect. The intrusion of large masses of plutonic rock often marks the close of a period of folding. This is well illustrated by the relation of granite to the surrounding rocks in the Lake District, the Southern Uplands of Scotland, and the west of England. Those of the two first-mentioned localities are post-Silurian and preCarboniferous, those of the last-mentioned locality are post-Carboniferous and prePermian; one set followed the Caledonian1 folding, the other set followed the Hercynian folding. That the intrusion of these granites was subsequent to the main movements which produced the folding and cleavage is proved by the fact that the mechanical structures may often be recognised in the crystalline contactrocks, although the individual minerals have not been strained or broken. In many other respects the rocks produced by so-called contact-metamorphism resemble those found in certain areas of crystalline schist. Many of the most characteristic minerals are common to the two sets of rocks, and so also are many structures. The cipolins and associated rocks of schistose regions have many points of resemblance to the crystalline limestones and 'kalksilicathornfels' produced by contact-metamorphism.2 These facts make it highly probable that, by studying the metamorphic action surrounding plutonic masses, we may gain an insight into the causes which have produced the crystalline schists of sedimentary origin; just as, by studying the intrusive masses themselves and noting the tendency to petrographical differentiation, especially at the margins, we may gain an insight into the causes which have produced the gneisses of igneous origin. In the districts to which reference has been made the igneous material came from below into a region where the rocks had been rendered tolerably rigid. Differential movement was not taking place in these rocks when the intrusion occurred. Consider what must happen if the folding stresses operate on the zone separating the sedimentary rocks from the 1 This term is employed in the sense in which it is used by Suess and Bertrand. 2 H. Rosenbusch, Zur Auffassung des Grundgebirges,' Neues Jahr. f. Miner., Bd. II. 1889, p. 8. 3 G. Barrow, On an Intrusion of Muscovite-biotite-gneiss in the South-eastern Highlands of Scotland, &c.,' Quart. Journ. Geol. Soc., vol, xlix. (1893), p. 330. underlying source of igneous material. Intrusion must then take place during interstitial movement, fluxion structures will be produced in the more or less differentiated igneous magmas, the sediments will be injected and impregnated with igneous material, and thermo-metamorphism will be produced on a regional scale. The origin of gneisses and schists, in my opinion, is to be sought for in a combination of the thermal and dynamic agencies which may be reasonably supposed to operate in the deeper zones of the earth's crust. If this view be correct, it is not improbable that we may have crystalline schists and gneisses of post-Silurian age in the north-west of Europe formed during the Caledonian folding, others in Central Europe of post-Devonian age due to the Hercynian folding, and yet others in Southern Europe of post-Cretaceous age produced in connection with the Alpine folding. But if the existence of such schists should ultimately be established it will still probably remain true that rocks of this character are in most cases of pre-Cambrian age. May not this be due to the fact, suggested by a consideration of the biological evidence, that the time covered by our fossiliferous records is but a small fraction of that during which the present physical conditions have remained practically constant? 6 The good old British ship Uniformity,' built by Hutton and refitted by Lyell, has won so many glorious victories in the past, and appears still to be in such excellent fighting trim, that I see no reason why she should haul down her colours either to Catastrophe' or 'Evolution.' Instead, therefore, of acceding to the request to hurry up' we make a demand for more time. The early stages of the planet's history may form a legitimate subject for the speculations of mathematical physicists, but there seems good reason to believe that they lie beyond the ken of those geologists who concern themselves only with the records of the rocks. In this address I have ventured to express my views on certain disputed theoretical questions, and I must not conclude without a word of caution. The fact is, I attach very little importance to my own opinions, at least on doubtful questions connected with the origin of the crystalline schists; but, as you have done me the honour to accept me as your President, I thought you might like to know my present attitude of mind towards some of the unsolved problems of geology. There is still room for legitimate difference of opinion on many of the subjects to which I have referred. Meanwhile, we cannot do better than remember the words with which one of our great living masters recently concluded an article on a controversial subject: 'Let us continue our work and remain friends.' 1 Some geologists maintain that this is the case, others deny it. See H. Reusch, 'Die fossilienführenden krystallinischen Schiefer von Bergen in Norwegen,' Leipzig, 1883; J. Lehmann, 'Ueber die Entstehung der altkrystallinischen Schiefergesteine, mit besonderer Bezugnahme auf des sächsische Granulitgebirge, Erzgebirge, Fichtelgebirge, und bairisch-böhmische Grenzgebirge,' Bonn, 1884; T. G. Bonney, several papers on the Alps, and especially On the Crystalline Schists and their Relation to the Mesozoic Rocks of the Lepontine Alps,' Quart. Journ. Geol. Soc., vol. xlvi. (1890), p. 188; A. Heim, contribution to the discussion on the last paper; C. W. Gümbel,Geognostische Beschreibung des K. Bayern' and 'Grundzüge der Geologie,' Kassel, 1888-1892. Although it is convenient to speak of the three types of folding which have so largely influenced the structure of the European continent as if each belonged to a definite period, it is important to remember that this is not strictly true. The movements were prolonged; they probably crept slowly over the surface of the lithosphere, as did the zones of sedimentation, so that those of the same type are not in all places strictly contemporaneous. The following Papers and Reports were read:: 1. Notes on the Water-bearing Capacity of the New Red Sandstone of Nottingham. By Professor EDWARD HULL, LL.D., F.R.S., F.G.S. About half a century ago, before the problems of sanitation were generally understood, the town of Nottingham was placed in a most unfavourable position as regards drainage and water-supply. As regards the former the drainage of the houses for the most part was run off into cesspools sunk in the sandstone rock on which the town is built; and as regards the latter the water-supply was drawn from wells sunk through the same formation down to the water-level, so that often the cesspools and wells were in proximity to each other. The result of such a state of affairs may easily be surmised. However excellent as a filter may be the sandstone rock, it must assuredly become clogged with fecal matter when filtration of water is carried on for an indefinite period, subject to such contamination as is here referred to, and in course of time the water from the wells becomes unfit for drinking and household purposes. Now all this is changed: the cesspools have been closed or filled up, and the water-supply is drawn from large and deep wells far removed from possibility of contamination. Few towns in central England are more favourably situated for purposes of water-supply than Nottingham. Built on a foundation of New Red Sandstone and conglomerate, which rises at the Castle in a precipitous cliff above the valley of the Trent, the formation on which the city stands in its prolongation northwards is a source of water supply of the highest excellence, and yields several millions of gallons per day of pure water from three or four wells situated within a few miles of the city. The conditions which render this formation so well adapted for water-supply may be briefly explained. The succession and character of the strata all combine towards this end. In descending order the succession is as follows: TRIAS PERMIAN Keuper Maris Waterstones and Lower Red and variegated marl, shaly and (Red Calcareous Marls. These are the strata separating the Upper and Lower limestones of Lower Magnesian Lime- Sandy magnesian limestones. stone From the above succession it will be seen that the permeable beds of the Bunter Sandstone, about 200 feet in thickness, are underlain by impervious marls of the Permian series, which thus form a water-tight floor, effectually preventing the water which percolates downwards from the surface to escape into the magnesian limestone; and, as the beds dip eastwards at a small angle from the western margin of the formation, an underground reservoir is thus formed with a naturally permanent level corresponding to that of the springs which break out at the junction of the sandstone with the marl along the western outcrop. The proportion of the rainfall, taken at an average of 30 inches, which sinks down into the Bunter Sandstone north of Nottingham must be very large owing to the absence of drift deposits and the sandy character of the ground. As there is no surface drainage the percolation cannot be less than about 20 inches per annum, giving a supply of about 1,000,000 gallons to every 3 square miles. Taking the area of the formation between Nottingham and Worksop at 120 square miles, the amount of water which annually percolates into the rock and becomes a reservoir of supply may be estimated at about 40,000,000 gallons per day. This large quantity of water tends to flow eastwards, following the dip of the beds; and that it has permanently saturated the Bunter Sandstone under an extensive area occupied by the overlying formations is proved by the result of the boring at Scarle, near Lincoln, which, commencing in the Lower Lias, passed down through the Keuper marls into the Bunter, when the water came up with force and flowed over the surface. This boring is at a minimum distance of 20 miles from the Two feeders of water were struck-one at a depth of 917 feet in the Lower Keuper Sandstone, and the other at 1,250 feet in the Bunter Sandstone. margin of the Bunter Sandstone. From these considerations it may be inferred that Nottingham is most favourably situated as regards its water-supply for a long period to come; a circumstance of great importance at a time when so many large manufacturing towns are looking forwards with anxiety to the future as regards this prime necessary of progress and prosperity. Since the above was written I have been favoured by Mr. L. T. Godfrey Evans, the Borough Engineer, with information, of which the following is a summary :There are four pumping stations, of which one, the Park, Zion Hill, is not now in use. The others are: 1. Basford or Bagthorpe, yielding 12,800,000 gallons per week. 3. Papplewick, yielding 12,190,000 In all 36,790,000 gallons per week, or 5,257,143 gallons per day. The supply at Bestwood is decreasing, owing probably to mining operations in the neighbourhood. The yield at the Park Station is about 5 millions of gallons per week. The water is excellent. 2. On a Nottingham Sandstone containing Barium Sulphate as a Cementing Material. By Professor FRANK CLOWES, D.Sc. (See p. 732.) 3. On the Discovery of a Concealed Ridge of pre-Carboniferous Rocks under the Trias of Netherseal, Leicestershire. By Professor EDWARD HULL, LL.D., F.R.S., F.G.S. It is now generally recognised that the Leicestershire and Warwickshire Coalmeasures were deposited along the borders of a land surface of older Palæozoic rocks, of which the visible representatives occur at Charnwood Forest and Atherstone. The attenuated condition of the Lower Carboniferous beds at Calke Abbey on the north of the Leicestershire Coalfield and their entire absence below the Coal-measures of Warwickshire show that these older rocks remained unsubmerged till the commencement of the Upper Carboniferous period, when they were gradually overspread, as the land became depressed, by successive deposits of the Coal period. The general north-westerly trend of these old foundation rocks, both at Charnwood Forest and Atherstone, appears to indicate that this old land was composed of a succession of ridges and furrows running in N.W. and S.E. directions; but as the country is for the most part covered by Triassic strata the position of such ridges and hollows can only be determined by experiment. One of these ridges appears to have been in this manner determined at Netherseal Colliery in a boring put down for the purpose of determining the extension of 'the main coal.' Having been invited by Mr. G. J. Binns, F.G.S., the manager of the colliery, to give my opinion regarding the age of the beds passed through in the lower part of the boring, I visited the colliery and inspected the cores which were brought up and were arranged in their order of relative depth at the works. The following is an abstract of the strata passed through:— TRIAS COAL-MEASURES PRE-CARBONIFEROUS J Bunter Sandstone; light reddish-brown, pebbly sandstone; 262 feet. Grey and black shales and sandstones, with coal and ironstone; plants abundant; 514 feet. Reddish, purple and grey grit, sandstone and 1 micaceous quartzite; 19 feet. The interest attaches to the beds called 'pre-Carboniferous.' They consist of sandstones, grits, and quartzites, of purple and yellowish tints, occasionally shaly. They contrast strongly with the Coal-measures, not only in the absence of beds of coal, grey and black shale and ironstone, but also in the complete absence of plant remains with which the overlying Coal-measures are crowded; not one solitary instance of any plant-form having been found amongst all the cores after careful examination. It became clear that the beds were not of Carboniferous age, yet it was very difficult to determine with certainty to what period they were to be referred. Such sandstones, grits, and quartzites might be found in several preCarboniferous formations, either the Old Red Sandstone, the Upper Silurian, Lower Silurian (Ordovician), or Cambrian. A reference to the Old Red Sandstone was considered out of the question, as this formation is not found anywhere in this part of England; nor did it seem probable that they were referable to the Upper or Lower Silurian period, though this is possible. On the other hand, we cannot forget that at no great distance to the south of the boring the Lower Cambrian beds form the floor of the Coal-measures, and, although the cores at Netherseal boring do not show a very strong resemblance to those of the Hartshill ridge, there is no good reason why they may not be referable to the same general period, and consist of beds not visible in that locality. For these reasons I am disposed with some hesitation to regard them as of Lower Cambrian age; a view in which I am supported by Professor Lapworth, who was kind enough to examine the specimens of the cores which I brought away with me from Netherseal Colliery. I will only add that no conclusion could be gathered regarding the question of unconformity of these beds with the overlying Coal-measures, as the dip of both series appeared to be very slight. A strong discordance could have been immediately detected. Since the above was written No. 2 boring has entered these old rocks, and the specimens brought up confirm the conclusion arrived at from the results of boring No. 1. The rock entered at a depth of about 760 feet consists of reddish vitreous quartzite, slightly micaceous, and very similar to the Hartshill stone of Warwickshire. 4. On the Geology of the Coastland of Caria. By JOHN L. MYREs. The interior of Caria, so far as it has been explored, presents only thick bedded blue and grey limestones of Cretaceous age, lying almost horizontally, and forming great plateaus with steep sea-slopes, the natural drainage falling partly into deep gorges, partly into the frequent swallow-holes. In the peninsula, however, which projects westward beyond Budrum (the ancient Halikarnassos) the occurrence of a volcanic series, both below and above the thick limestones, causes a complete change in the character of the country. The 'fundamental' beds of this area are light-coloured crystalline quartzose and felspathic rocks, which are interbanded with one another, and present occasionally traces of foliation. The dips are almost universally to the east, and rise in some places to the vertical, but are not wholly pre-Cretaceous. The age of these beds is quite undetermined, but they may probably be correlated with the very similar beds in Patmos, and with those which underlie the thick limestones in the eastern half of the peninsula of Kavo Krio further south, and the white marble series which represents them in Naxos, Attica, and elsewhere. These beds are traversed, as in Patmos and Naxos, by numerous necks and dykes of very various composition. Two or three types, however, may be distinguished, and appear to represent successive periods of volcanic action. In particular, a purple porphyritic rock which is especially common in the neighbourhood of Gumashli (ancient Myndos), on the west coast, occurs as the main constituent in an altered tuff, underlying the basal schists of the limestone series, in which several other common types are not represented. The pre-Cretaceous volcanic outbreak was not yet over when the great subsidence began at the opening of the Limestone period; for the last deposits of débris on the flanks of the old land-mass have a distinctly subaqueous character, and are immediately succeeded by fine clays and schists at the base of the great limestones. The lower part of this series is in this region unusually full of thin sandy beds, and it contains also a number of bands of black chert in the parts east of Budrum. The higher beds, however, are cleaner, and conform to the more normal type represented in the neighbouring areas of Kavo Krio, Kos, and Kalymnos. Öne small outlier in the middle of the volcanic area has been wholly metamorpho sed |