Repots and Proceedings

Geological Society of London. 281 Those who like their science and religion mixed will be grateful for a book in which a little Theology is given, but the mixture is very incomplete, hardly penetrating beyond the opening and the end chapters; and so little is said of the Divine beneficence and wisdom, that no help—new or old—is given to those who endeavour to see it in the fratricidal struggle for existence. To attempt this task and the like, and yet to shrink from grappling with the logical difficulties in the path, will not soothe the troubles which may afflict the mind when matters of belief are mixed indifferently with matters of argument. And although by the terms of the bequest of which this book is a fruit, the task may be attempted only every seven years, we trust that the wisdom and goodness of the Almighty may another time be the pervading theme, or else that science may hold a place that will make it clear that the scientific and theological methods are not one and the same. H. G. S.

EEPOBTS

GEOLOGICAL SOCIETY OF LONDON.—March 25th, 1874.—John Evans, Esq., F.E.S., President, in the Chair. The following communications were read :—• 1. " On the Upper Coal-Formation of Eastern Nova Scotia and Prince Edward Island, in its relation to the Permian." By Principal Dawson, LL.D., F.E.S., F.G.S. The author described the Carboniferous district of Pictou county as showing the whole thickness of the Carboniferous system arranged in three synclinals, the easternmost consisting of the Lower series up to the Middle Coal-formation, and including all the known work- able Coal-measures in the district,—the second towards the west of the middle and the lower part of the Upper Coal-formation,—and the third showing in its centre the newest beds of the latter. On the north the bounding anticlinal of the first depression brings up the New-Glasgow Conglomerate, which contains boulders 3 feet in diameter, often belonging to Lower Carboniferous rocks, and repre- sents the upper part of the Millstone-grit or the lower part of the Middle Coal-formation. The author regards this as representing an immense bar or beach, which protected the swamps in which the Pictou main coal was formed. The succession of the deposits above the Conglomerate was described in some detail as seen in natural sections. The Upper Coal-formation, as shown in the section west of Carribou Harbour, consists of, 1. Ked and grey shales, and grey, red, and brown sandstones ; and 2. Shales, generally of a deep red colour, alternating with grey, red, and brown sandstones, the red beds becoming more prevalent in the upper part of the section. In Prince Edward Island beds apparently corresponding to these are found, and also gradually become more red in ascending. These are .overlain, apparently con- formably, by the Trias.

Downloaded from https://www.cambridge.org/core. INSEAD, on 21 Sep 2018 at 22:34:10, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0016756800168098 282 Reports and Proceedings— The author gave a tabular list of 47 species of plants found in the Upper Coal-formation of Nova Scotia and Prince Edward Island, and stated that all but about ten of these occur also in the Middle Coal-formation. The number of species decreases rapidly towards the upper part of the formation; and this is especially the case in Prince Edward Island, some of the beds in which are considered by the author to be newer than any of those in Nova Scotia. The plants contained in the upper deposits were compared with those of the European Permian, and a correlation was shown to exist between them, so that it becomes a question whether this series was not synchronous with the lower part of the Permian of Europe, although in this district there is no stratigraphical break to establish a boundary between Carboniferous and Permian. The author therefore proposes to name these beds Permo-Carboniferous, and regards them as to some extent bridging over the gap which in. Eastern America separates the Carboniferous from the Trias. DISCUSSION.—Prof. Ramsay agreed with the author in thinking that these Upper Carboniferous rocks represented the Permian, and that there is a gradual passage from the Carboniferous to the Permian. In North Staffordshire there is some evidence of this passage, but not in other parts of England. Mr. Binney had argued that the Permian is the uppermost part of the Carboniferous series ; but this is not true in the English area, although it is true if we consider the globe in general. The Coal-measures are grey, black, and blue; but in the upper portion they change to a red tint. During the Coal period we have evidence of estuarine conditions, but subsequently the access of the sea was cut off, and the Permian rocks were formed in vast inland lakes. Prof. Hughes remarked that the group referred to by Principal Dawson under the head of Permo-Carboniferous could not be considered as in any way proving a passage from Carboniferous to Permian, seeing that the Permian was altogether wanting in Eastern America, unless the fossils approached those of undoubted Permian in Europe. But he pointed out that many large portions of the so-called Permian of Europe had been already proved to be only stained Carboniferous. The fossil lists were founded on a wrong classification of the rocks, which had not yet been set right. Believing, therefore, that the Permian system must be broken up and part given back to the Lower New Red and Magnesian Limestone series, previously so well established, and part to the Upper Carboniferous, he was inclined to refer the Permo- Carboniferous of Principal Dawson to the latter, the difference in the plants being only such as might reasonably be expected between the newer and older portions of a series representing immense lapse of time and changing conditions. Principal Dawson had shown that the beds in question were similar in almost all but colour, and conformable to the underlying undoubted Carboniferous. If, therefore, they were higher than any Carboniferous beds of England, they must be synchronous with the lower part of the unrepresented time between the Carboniferous and so-called Permian ; but being more closely connected with the lower rocks, he saw no necessity in the present state of our knowledge for such a term as Permo-Carboniferous. Prof. Ramsay could not agree with Prof. Hughes in his opinion as to the value of the term Permian. The staining of rocks occurs in two ways, namely, by infiltration from above through overlying beds, and by direct deposition. Silurian rocks are often stained in the former manner. The President remarked that this paper had given rise to an interesting discussion. The fact of two deposits being conformable in one place and unconformable in another, does not necessarily convert them into one system. He thought there were symptoms that the Permian would eventually be reckoned Upper Carboniferous. He believed that there was a third mode in which rocks were stained, namely, by the oxidation of iron already existing in the beds. 2. " Note on the Carboniferous Conglomerates of the Eastern Part

Downloaded from https://www.cambridge.org/core. INSEAD, on 21 Sep 2018 at 22:34:10, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0016756800168098 Geological Society of London. 283 of the Basin of the Eden." By J. G. Goodchild, Esq. Communi- cated, by permission of the Director-General of the Geological Survey of the United Kingdom, by H. W. Bristow, Esq., F.R.S., F.G.S. The author commenced by describing in detail the series of beda between the true Basement series of the Carboniferous and the Mountain Limestone as shown in sections at Ash Fell. The general sequence in descending order is as follows :— a. Carboniferous Limestone, with a few thin beds of stained sandstone and shale ; thickness not less than 1000 feet; h. Obliquely laminated soft, red sandstones, with coal-measure plants, frequently conglomeratic, alternating with fossiliferous shales and beds of limestone; thickness about 500 feet; c. Limestone, 500 or 600 feet thick, passing down into d. Shales with thin impure limestones, passing down through calcareous conglomeratic beds into a series of apple-green quartz conglomerates and chocolate and grey shales, succeeded without any clear line of separation by the drift-like red conglomerates, sandstones and shales forming the lower part of the Carboni- ferous Basement beds, which has been regarded as,the equiva- lent of the Upper Old Eed elsewhere. The author described the mode of occurrence of these deposits in various parts of the district under consideration, and the disturbances which have affected their surface distribution. Along the Cross Fell escarpment a group of sandstones and conglomerates occupies an exceedingly prominent position, especially at and near Roman Fell, whence the author proposes to call these deposits the Eoman Fell beds. These beds represent the series b, and also the lower part of a, at Ash Fell. Following their outcrop towards Cumberland, the conglomeratic beds from the middle downwards increase much in thickness and become much coarser. The author regards the Eoman Fell beds as approximately on the horizon of the Calciferous Sand- stone series of the south of Scotland, and he remarks that they are locally undistinguishable from much of the Basement series, and have been described by authors as undoubted Old Eed Sandstone. DISCUSSION.—Prof. Hughes confirmed the observations of Mr. Goodchild, and Bhowed their importance as bearing upon inquiries into the changes of the land which furnished, and of the currents which arranged the materials of the beds described. Prof. Ramsay remarked that the author was entitled to much praise for the manner in which he had worked out the minor details of the Carboniferous system. The Cross Pell had been called Old Eed Sandstone ; it is now placed in the Lower Car- boniferous, but no distinct line of demarcation can be determined. Prof. Uamsay remarked on the distribution of deposits of the Carboniferous series in Britain, and referred especially to the Carboniferous limestone. In the south of Pembroke and Glamorganshire this formation is 2500 or 3000 feet thick; in the Devonshire area 100 feet, and in the north of Glamorganshire 500-600 feet represent the whole of the Mountain Limestone ; in Coalbrook Dale, again, its thickness is only about 100 feet, in North Wales 800 feet, in Anglesea 500 feet. In advancing towards Palaeo- zoic districts, where old land existed, the limestone becomes thin, whilst it becomes thick in the deep water areas,—in Derbyshire 3000-4000 feet, falling off to less than 1000 feet in Cumberland, where it is split up by sandstones; and this is still more strikingly the case in Scotland, where 100 feet of limestone is a rarity. He thought the existence of Coral Beefs in the Mountain Limestone doubtful.

Mr. Tiddeman remarked that the Mountain Limestone was 3000 or 4000 feet thick in the Lake-district, and in the Pennine Chain, at a distance of 15 miles, only 600 ft. 3. " An Account of a Well-section in the Chalk at the North End of Driffield, East Yorkshire," By E. Mortimer, Esq. Communicated by W. Whitaker, Esq., P.GS. In this paper, which was in continuation of a former communica- tion to the Society (Q. J. G. S. vol. xxix. p. 417), the author stated that the well-section referred to passed through 7 feet of clay and 47 feet of chalk, the upper 3 or 4 feet of the latter very rubbly and broken. The chalk was bedded in lamina? of from TV in- to 16 in. thick. From a depth of 20 feet downwards the well exposed many nearly vertical partings running in all directions through the Chalk, and the surfaces of the blocks thus marked out showed numerous strias, such as were described in the author's former paper. These stria? were in most cases horizontal, but some surfaces snowed them at an angle of 45° to the horizon. The laminae of which the chalk was composed were separated by layers of a softer substance like Fuller's earth, containing 1-67 per cent, of organic matter, 7-05 per cent, of oxide of iron, 10-23 per cent, of alumina, and 3480 per cent, of silica. The author regards this soft substance as formed by the disintegration of chalk, shells, etc., caused probably by the periodical prevalence of great waves or other disturbances in the Cretaceous sea. The effect of its formation he considers would be to check the upward growth of the mass of chalk, which he now, as formerly, ascribes to the direct secreting action of numerous zoophytes. In support of this view he states that the surfaces of the chalk laminae are more or Jess irregular, and not even as if produced by quiet sedimentary deposition. The paper contained detailed analyses of the chalk and of the soft partings. DISCUSSION.—Prof. Hughes thought that the origin of the particular structure referred to by Mr. Mortimer was a question for mineralogists and chemists, though somewhat similar forms might be produced mechanically. He pointed out that its occasional occurrence along fissures not in the line of bedding was quite conclusive against its being in any way referable to the period of original deposition. As to the more clayey bands, he considered the Chalk, though often composed in a great measure of comminuted organisms, to be all sedimentary, and had therefore no diffi- culty in explaining how more clayey matter might accumulate over various areas at different times. Mr. Wiltshire mentioned that argillaceous bands extending over wide areas are to be observed in the Chalk. Mr. Whitaker stated that clay bands occur near Beachy Head. He considered that the argillaceous bands are not seen in hard chalk. The analyses given by the author were of much value. Mr. Charlesworth remarked that the Yorkshire Chalk presents exceptional charac- ters. The sponges found fossilized in it are silicified throughout, but the silica is confined to the sponges, and does not invest them. Mr. Koch stated that near Nice the Dolomitic Limestone sometimes exhibits a structure similar to that described in the paper, and that when this structure occurs, minute crystals can be detected in the mass. 4. " On Slickensides or Eock-striations, particularly those of the Chalk." By Dr. Ogier Ward. Communicated by Prof. Morris, F.G.S. The author referred to previous communications on this subject,

Downloaded from https://www.cambridge.org/core. INSEAD, on 21 Sep 2018 at 22:34:10, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0016756800168098 Correspondence—Rev. 0. Fisher. 285 and maintained that the striae observed in chalk are to be regarded as slickensides caused by disturbance and movement of the rock. He described the appearances in detail, and mentioned the occurrence of similar striations in various rocks. DISCUSSION.—Mr. Whitaker said that some of the specimens on the table sent by Dr. Ward showed eliekensides, but that in certaiu cases the fibrous structure runs through the whole substanee. Mr. W. T. Blanford stated that he had seen a similar structure in an undisturbed white clay resembling pipeclay, so that he thought the appearance could not be produced by motion. The President remarked that the structures brought forward appeared to be of two kinds : first, slickensides pure and simple ; and secondly, fibrous structure, the latter probably due to chemical action, either by an incipient formation of aragonite, or by the formation of that mineral and its subsequent partial decomposition.

ON THE CHESIL BANK. SIR,—I am glad of the opportunity, given by Mr. Kinahan's question, to explain what I mean by a " drowned valley." I apply this term to an inlet of the sea, which occupies a valley originally subaerial, and excavated by subaerial causes, but into which the sea has subsequently run, owing either to a subsidence of the land, or, if such a thing be admitted as possible, by a raising of the level of the ocean at the locality. There are many causes which, to my mind, seem to point to the latter as having really happened. In many parts of the English coast old cliffs may often be traced where high ground meets alluvial tracts of salt marsh. I believe them to have been formed during the period of the formation of the Scrobicularia Clays which overlie the submerged forests. These cliffs do not indicate the mode of formation of the bays, which have since become alluvial tracts, but are merely traces of their slight enlarge- ment after the sea had gained access to their areas. The order of events has been:—1. Excavation of the valleys by Bubaerial causes. 2. Growth of forests now submerged. 3. Depres- sion ; and formation of Scrobicularia Clays and low cliffs—probably the period of the 30 feet raised beaches. 4. Slight re-elevation, and silting up of some of the estuaries (not of all), bringing them into their present condition. The reason why I affirm that there were never marginal cliffs to the Fleet is, because I have seen no vestiges of them. The gently undulating surface of the ground declines gradually to the water's edge; and I have collected fossils from the outcrop of the beds at the edge of the Meet, where, if there had been formerly cliffs, we ought now to find tumbled talus. Mrs. Bristow's characteristic sketch, in Vol. VI. of the MAGAZINE, gives an exceedingly good idea, of the ground, it being premised that all shown is upland. There is no alluvial ground shown in it. The only alluvial tract is a small part at the extreme head of the estuary, which in the sketch is hidden by a projecting mound. Beferring to the questions opened by Colonel