478 



NATURE 



[August 14, 19 19 



returns made to the Ministry of Munitions in 

 December, 1917, it appears tliat the average output in 

 the Midlands per man employed was 5 tons per shift, 

 and that it ranged from 3-8 tons where hand-labour 

 was alone employed to more than 15 tons where 

 mechanical excavators were in use under favourable 

 •conditions. The actual saving of manual labour which 

 resulted from the installation of mechanical plant in 

 the ironstone quarries during the war is estimated to 

 have been equivalent to more than 3000 men. 



The Jurassic ironstones have a wide distribution 

 both in this country and on the Continent. In 1913 

 Germany mined in Lorraine and Luxemburg 

 28,000,000 tons of minette ores of Jurassic age out 

 of a total production of 36,000,000 tons of iron-ore, 

 while she imported in addition 3,800,000 tons of the 

 same ore from Briey. Without 'the Lorraine iron-ore 

 basin, which she stole from France in 1871, Grermany 

 would have been unable to go to war, and she took 

 care to secure the remaining portion of the) field (i.e. 

 the Longwy and Briey basins) soon after the com- 

 mencement of hostilities. One of the best guarantees 

 for future peace is the provision in the Peace Treaty 

 that no portion of this iron-ore field remains in 

 ■German hands. 



In England the Jurassic formation stretches as a 

 broad band from the coast of Yorkshire to that of 

 Dorset. The ironstones occur on four different 

 horizons, as shown in the following table, which also 

 gives the proportion in which they were worked (in 

 relation to the total production of the United Kingdom) 

 in 1917, and their average iron-content. 



Table showing Relative Production and Iron-content 

 of the Jurassic Ironstones. 



Ironstone ^«"° '«> '°'^' 



production. 



Per cent. 



Inferior Oolite (Northampton- 

 shire and Rutland) ... 21 



Middle Lias (Cleveland) 



Middle Lias (South Lincoln- 

 shire, Leicestershire, and 

 Oxfordshire) 



Middle Lias (Raasay) 



Lower Lias (North Lincoln- 

 shire) 



32 



9 

 0-5 



Average iron 



content 

 (as mined). 

 Per cent. 



I» 23 



8o-s 27-6 



The Jurassic ironstones accounted in 1917 for more 

 than 80 per cent, of the total output of iron-ore in 

 the United Kingdom, the remaining 20 per cent, being 

 made up of hgematite mined in Cumberland and Lan- 

 cashire (io| per cent.), blackband and clay-ironstone 

 mined in the English and Scottish coalfields (8 per 

 rent.), and sundry ores mined in Wales, Forest of 

 Dean, Devonshire, Weardale, and Ireland (ih per 

 ■cent.). 



The Jurassic ironstones, although poor in iron, are 

 valuable because of their considerable thickness and 

 widespread occurrence at only a slight depth below 

 the surface. With the exception of the Cleveland 

 district of Yorkshire, where the ironstone is now 

 mined underground, the workings are almost every- 

 where at the surface, the ironstone being quarried 

 after stripping off an overburden of soil, sand, or clay, 

 as the case may be. Since the angle of the dip is 

 iisually small — or, in other words, the beds are prac- 

 tically horizontal — considerable areas can be worked 

 before the overburden becomes, too great for removal 

 at a reasonable cost. .^s much as 60 ft. of soft 

 material (sand or clay) can be removed, and, under 

 favourable conditions, probably 100 ft. will be re- 

 moved. 



The different beds of ironstone vary considerably 



NO. 2598, VOL. 103] 



in thickness. The thickest is the Frodingham bed 

 m North Lincolnshire. This ironstone is 25 ft. to 

 30 ft. in thickness, and consequently can be worked 

 very cheaply by mechanical excavation. Before the 

 war the cost of the stone in wagons at the quarries 

 (exclusive of royalty) was not more than is. per ton. 

 Probably it is double that now. 



As compared with 19 16 figures, the production of 

 the Jurassic ironstones as a whole was increased by 

 45,000 tons per week, equivalent to 2I million tons 

 per annum. The Increase reached this maximum in 

 the first half of the year 19 18. But it was not 

 possible to maintain production at that figure on 

 .account of the calls of the Army on labour. The 

 increase was made mainly In Northam,ptonshire, Rut- 

 landshire, and Leicestershire, the quarries in these 

 counties accountin<:« for 59 per cent, of the total 

 Increase ; but Cleveland accounted for 26 per cent, and 

 Oxfordshire for 9 per cent. 



With regard to the non-Jurassic iron-ores of this 

 country, the most important are the haematite deposits 

 of Cumberland and Lancashire. These ores are 

 remarkable for their richness in iron and their freedom 

 from both phosphorus and sulphur, and therefore fur- 

 nish a pig-iron very suitable for the acid Bessemer 

 process, and yield an exceptionally pure steel. They 

 are, consequently, in great' demand, 'and this demancl 

 was emphasised during the war bv the difficultv at 

 one time experienced in securing sufficient supplies of 

 haematite ore from Spain. Every effort was therefore 

 made to push production to the utmost, and many 

 abandoned mines were reopened in order to extract 

 the pillars. 



The deposits occur in masses of irregular shape in 

 the Carboniferous Limestone, a formation which in 

 this district rests unconformably on the old Skiddaw 

 Slates, and is itself concealed In places by overlving 

 Coal Measures and Red Sandstones or by Boulder 

 Clay. The existing mines are situated between 

 Lamplugh, in Cumberland, and Ulverston, in Lanca- 

 shire, a dis^tance from north to south of thirtv-five 

 miles. 



No doubt, besides the known deposits, many un- 

 discovered ore-bodies exist in the Carboniferous Lime- 

 stone that can be found onlv bv svstematic prospect- 

 ing by boring. Already before the war borings through 

 the Red Sandstones had disclosed, south of Egre- 

 mont, some of the largest ore-bodies that have been 

 found in either county, with the possible exception of 

 that worked by the Hodbarrow mine. The Beckermet, 

 Ullcoats, and Ullbank Companies are now engaged in 

 developing and working these deposits. 



Since the Carboniferous Limestone Is of widespread 

 occurrence in the United Kingdom, it might have been 

 expected that valuable haematite deposits would have 

 been discovered In other parts of the country. With 

 the exception, however, of deposits of limited extent 

 in South Wales and in the Foresit of Dean, this has 

 not proved to be the case. 



In the industrial recuperation of this country, now 

 that the war is over, the working of the low-grade 

 Jurassic deposits, which it is fortunate In possessing, is 

 destined to play a great part. This has been rendered 

 possible by the great extensions to iron and steel 

 works that have been initiated with Government 

 assistance during the war. These works have been 

 planned on the most modern lines, and possess on 

 the same site by-product coke-ovens, blast-furnaces, 

 steelworks, and rolling mills. They are designed for 

 the basic process of steel-making, and will be fed 

 with home ores. In choosing the sites for these 

 works regard has been paid to the situation of the 

 raw materials — ore, fuel, and flux — required to supply 

 them. On the completion of these extensions there 



