barley and clover had a great deal of charlock everywhere in it, and in some places in the field it was the predominant crop. Mr. Hornsby selected this field for trial and sprayed several plots. The charlock was in pod and the yellow flowers were still expanding. He sprayed with a 4 per cent. solution. The result was that every charlock plant was so completely killed down to the crown of the root that no food was conveyed through the stem to the seed pods -flowers, pods, foliage, and stem were all destroyed. In a very few cases the roots still remained alive, and a new branch had been sent out from the crown after the copper sulphate had done its work on the rest of the plant. The vegetation on the plots was otherwise not in the least affected. The barley was not less vigorous. The weeds were not touched by it. Chickweed, pansy, and bindweed were unharmed. Even the tender young clover was not in the least affected by the spray. Indeed, the clover was rather more vigorous in the sprayed plot than in the surrounding field, for the killing the charlock had given air and light to the vegetation which was previously choked by that weed. I have not been able to detect anything in the structure of the charlock that should make it so readily a prey to the copper sulphate. The selection of the charlock for destruction is still more remarkable when we find that it does not in the least injure another species of the same genus, which in Cumberland is known as the 'smooth-leaved charlock.' This plant, the Brassica campestris of Linnæus, is very common in some districts. A correspondent in Cornwall writes that it is very common in his county. He has observed that, while the common charlock is easily destroyed by copper sulphate, the smooth-leaved plant is quite uninjured by it. This is probably the explanation of the difference in the testimonies as to the influence of copper sulphate on charlock. The two plants so closely resemble each other that only a careful observer can distinguish that they differ. The true charlock (Brassica sinapistrum, Boiss.) is destroyed by treatment, while the smooth-leaved charlock (Brassica campestris, Linn.) is not affected." As the general outcome of Mr. Hornsby's experiments, it would seem that for charlock when still young 40 gallons per acre of 2 per cent. solution of sulphate of copper would be found effectual, but that if the charlock be already in flower as much as 60 gallons of a 4 per cent. solution would be required. Mr. Hornsby points out that the cost of such an application would be only about 4s. per acre, while it would cost from 30s. to 35s. an acre to hand-pull the charlock, and, moreover, a quantity of clover would be pulled up along with the charlock. SUMMARY. A review of the preceding account of experiments conducted in different parts of the country will lead to the following general conclusions. 1. It can hardly be doubted that suitable spraying solutions when applied under proper conditions, are capable of destroying charlock to a very great extent when it occurs in corn and other crops, without the crop itself being injured. All the experiments recorded, with the exception of those at Wye College, bear out this general conclusion, though it is clear that much is still to be learnt as regards the influence of the conditions that prevail at the time of application of the dressing. 2. Of spraying solutions, sulphate of copper is, on the whole, the best. Sulphate of iron is more uncertain, more unpleasant to use, and, though cheaper in cost, requires to be used in so much larger quantity than sulphate of copper, that the cost comes in either case to about the same. In the Essex experiments sulphate of iron of 12 per cent. strength and sulphate of copper of 2 per cent. strength did about equally well. In the Uckfield experiments sulphate of copper was the better, and in Mr. Hornsby's experiments sulphate of iron was quite useless. In the Yorkshire experiments alone was sulphate of iron preferred, but sulphate of copper was not given nearly such an extended trial. 3. Successful spraying depends largely upon the conditions prevailing at the time of application. These are mainly: (a) the state of the weather, and (b) the age of the charlock. The weather should be dry and calm, and not wet, windy, or even frosty. If rain follows soon after application, respraying may be necessitated. All the experiments point to the conclusion that charlock ought to be sprayed in quite the early stages, and before the flowerheads appear. Its destruction, or at least check, even in the later stages, and when flowering has taken place, is, however, not hopeless if stronger solutions and larger quantities be employed. 4. As regards strength and quantity of solution to employ, considerable variety of opinion exists, but it would appear that it is not desirable to use less than 40 gallons per acre, and that, while a 2 per cent. solution of sulphate of copper will, as a rule, be successful in destroying charlock when in the quite young stage, a 3 per cent., or even 4 per cent., solution may be needed if the charlock be more advanced, or be specially thick on the ground. 5. As regards method of application, a knapsack sprayer costing 30s. will serve for quite small areas, but for larger areas a barrel, with spraying appliances, must be mounted in a cart; such a machine would cost about 8l., or, with automatic action to avoid hand-pumping, about 157. From 20 to 30 acres, according to the land, could be sprayed in a day, and the cost of materials and application would be from 38. to 4s. per acre. 6. Nothing is definitely known as to why charlock should be destroyed by salts of copper and iron, but the hitherto accepted theory that the roughness of the charlock leaves is the influencing cause, seems to be disproved. 13 Hanover Square, W. J. AUGUSTUS VOELCKER. THE GEOLOGICAL SURVEY OF ENGLAND AND WALES.' THE following extracts from the Summary of Progress of the Geological Survey for 1897, by the Director-General (Sir Archibald Geikie, LL.D., F.R.S.), are such as relate to matters of agricultural or other economic interest. OLD RED SANDSTONE. South Wales.-During the re-survey of the South Wales coalfield it has been necessary to map the underlying formations which come into the areas contained within the sheets of the coalfield map. In the course of this revision further progress was made with the tracing of the Old Red Sandstone. A small area occupied by this formation in the Ely Valley, in the county of Glamorgan, was found by Mr. Cantrill to consist of red sandstones and quartzconglomerates, which produce well-marked features west of Groesfaen and along the elevated grounds of Hensol Park. The strata exposed all belong to the higher part of the system. The escarpment formed by the Old Red Sandstone on the north side of the coalfield, which reaches a height of 2,906 feet in the Brecknock Beacons, falls partly within the area of Sheet 231, and has been examined by Mr. Cantrill. The lowest beds exposed within the area are well displayed at the heads of Glyn Tarell, Glyn Senni, and the Dringarth Valley. They consist of rapid alternations of red and green sandstones, shales, and marls, with numerous thin red and green cornstones, usually two or three feet thick, and consisting of a mass of small rounded fragments of limestone in a sandy and calcareous matrix. Pebbles of quartz and sandstone also occur in these calcareous bands, and sometimes the limestone pebbles diminish in number until the rock becomes a calcareous pebbly sandstone. In the Dringarth Valley, where these strata occur as an inlier, there are exposed also some grey and black shales with indefinite traces of plants. The colour of these cornstone-bearing rocks varies rapidly, and in Glyn Senni some of the cascades exhibit a thick green series. Micaceous flaggy green sandstones have been worked near Blaen Senni for roofing, paving, and tombstones. These strata pass upwards into a great thickness of alternating red sandstones, shales, and marls, with occasional beds of massive coarse sandstone, frequently false-bedded, and containing quartzpebbles. Regarded in a broad aspect, the series may perhaps be said to be characterised by massive coarse sandstones in the lower part, thick marls with sandstones in the middle, and hard brickred sandstones and marls in the upper parts. Traces of cornstones The work of the Geological Survey was described in this Journal, 3rd series, vol. v., 1894, pp. 140-162. occur even in the uppermost beds. The hard sandstones of the upper parts give rise to the characteristic feature of this Old Red Sandstone tract-namely, long gently inclined plateaux, bounded by precipitous crags, which lead up to the escarpment. The Brecknock Beacons consist of these red sandstones up to their summits, unlike the more prominent hills in Monmouthshire, all of which are capped by the uppermost conglomeratic subdivision of the Old Red Sandstone. TRIASSIC (AND RHETIC). North Staffordshire. In the course of the revision of the North Staffordshire coalfield it has been necessary to retrace some of the areas of Triassic rocks. In regard to this part of the field-work Mr. De Rance reports as follows:-No Lower Mottled Sandstone occurs in North Staffordshire, the Pebble Beds of the Bunter resting on the denuded edges of all members of the Carboniferous series. The beds are very loosely aggregated, and the pebbles in them are invariably "pock-marked," as in Cannock Chase. Occasionally hard bands occur, in which the pebbles are never marked, as is the case also in the hard sandstones of Lancashire and West Cheshire. A boring at a point a few miles north of Birkenhead, in a fruitless search for coals, proved the pebble beds to be there above 2,000 feet in thickness. They thin south-eastwards no less than 1,400 feet in fifty miles, or an average of 28 feet per mile. The Upper Mottled Sandstone is hardly in evidence at Creswell, and at Fullford has entirely disappeared, as in the Nottingham area. Yet on the Manchester Ship Canal it is 600 feet thick. Its attenuation in a distance of forty miles thus amounts to 15 feet per mile between South Lancashire and North Staffordshire. The Lower Keuper building-stones and basement-beds with currentbedding are not clearly cut off from the Waterstones with "wayboards" as in Cheshire. The whole series, with the Keuper marls above, reaches a united thickness at Blythe Bridge and Fullford of less than 1,000 feet, against 2,500 proved in Salt Union boring at Marston, Northwich, 30 miles distant, giving a south-easterly attenuation of 50 feet per mile. CRETACEOUS. Devonshire.-During the summer Mr. Jukes-Browne was able to examine the Upper Cretaceous strata near Honiton in Devonshire. He paid special attention to the outlier of chalk which occurs at Widworthy, between Wilmington and Suttonthorpe, as this is the most westerly inland tract of chalk in England. The old quarries, which had been observed by De la Beche and Fitton, were found to be almost wholly overgrown; but the fact was ascertained that a bed of freestone resembling the well-known Beer-stone had formerly been worked. Mr. Jukes-Browne satisfied himself that the two beds of freestone were on the same horizon. At Wilmington he VOL. X. T. S.-40 3 F found sections which showed the succession to be similar to that at Beer Head on the coast and different from that seen at Membury, only 4 miles to the north-east. At Membury the Lower Chalk is still chalk, and appears to be 50 or 60 feet thick; at Wilmington there is no such chalk, its place being taken by calcareous sand and sandstone containing many fossils and resembling the beds which have been described as Cenomanian in the coast-section. Southern Counties. The assistance referred to in the Survey Report for 1896 as being rendered to the Geological Survey by Mr. William Hill in the re-examination of the chalk for the purpose of more precisely tracing the distribution of its zones has been continued by him during the past year. He has now completed this useful work, and has collected a large body of fresh material to be used in the preparation of the memoir on the Upper Cretaceous formations and in the further revision of the maps. Mr. Hill's investigations included an examination of the chalk of Margate, the quarries in the Upper Chalk near Chatham, Rochester, and Strood, where he identified the "Chalk with Marsupites" about 1 mile north-west of the last-named town. He has continued the examination of the Upper Cretaceous series around the southern margin of the Wealden area, visiting Petersfield, Arundel, and Lewes, and taking detailed notes of all important sections. The result of these traverses shows the continuity of the various zonal divisions of the Upper Cretaceous series. In the Isle of Wight Mr. Hill studied the cliff sections, with the object of determining the true base of the chalk and of obtaining more complete details of the beds composing the Upper Greensand and the Lower, Middle, and Upper Chalk. He measured the Upper Greensand at Culver, at St. Lawrence, near Niton, and at Gore Cliff. He examined with care nearly every available section which showed the junction of the Upper Greensand with the chalk, and came to the conclusion that the true base-line of the chalk could be drawn immediately above a certain bed which, stretching with some persistence, seems to suggest a line of erosion, and marks a lithological change in the nature of the deposit. The fossils subsequently obtained from this locality by the Survey Collector threw doubt on the zonal value of this divisional line. Mr. Hill examined and measured the Lower Chalk of Culver Cliff and Compton Bay, finding its thickness at Culver to be 203 feet and at Compton Bay 150 feet. He further ascertained the Middle Chalk at Compton Bay to be 135 feet in thickness, compared with 174 feet at Culver. The Belemnite Marls and Melbourn Rock are well developed, while the summit of the Middle Chalk is marked by a considerable thickness of exceedingly hard rough nodular chalk. He further obtained detailed sections of many of the more important quarries inland, particu See Journal R.A.S.E., 3rd series, vol. ix., 1898, p. 795. |