Philosophical Magazine Series 1

ISSN: 1941-5796 (Print) 1941-580X (Online) Journal homepage: http://www.tandfonline.com/loi/tphm12

XXX. A sketch of the natural history of the rock-salt district

Henry Holland Esq.

To cite this article: Henry Holland Esq. (1812) XXX. A sketch of the natural history of the Cheshire rock-salt district , Philosophical Magazine Series 1, 39:167, 210-215, DOI: 10.1080/14786441208638112

To link to this article: http://dx.doi.org/10.1080/14786441208638112

Published online: 27 Jul 2009.

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Download by: [University of Toronto Libraries] Date: 04 June 2016, At: 23:23 ~10 .,4 Sketch of the Natural HMory of being in the focus to which the other radiates, it must f~t- cititate the escape of caloric from the other, by quickly ab- sorbing all that is sent to it by radiation from that other body. In the common experiment the thermometer is the radiating body, and the ice the absorbent. A.T.

XXX. ,4 Sketch of the Natural History of the Cheshire Rock-Salt District. By HENav HOLLAI~D, Esq. Ho- norary Member of" the Geological Society *¢. THE vast beds of fossil or rock-salt, which are found in different parts of the county of , thrill undoubtedly the most important and peculiar feature in the mineralogy of this district. In offering to the notice of the Geologic-a] Society some remarks upon these mines, it may be proper to premise, that in a Survey of Cheshire, which I had the honour of drawing up for the Board of Agriculture, I en- tered at considerable length upon the subject of their na- tural history,-and upon the manufacture of white salt froru the brine springs to which they give rise. It will be my present object to consider more especially the mineralogical situation and characters of the Cheshire rock-salt; and though the repetition of some statements must necessarily occur ; this, in the case of a work only partially known, can, I conceive, be attended with little disadvantage. Character of the Country surrounding the Salt Mines. In speaking of the general situation of the Cheshire salt mines, it will be proper to state some facts with respect to the nature of the surrounding country, timt their mineralo- gical relations may more clearly be understood, and an op- portunity given to speculate upon the probable origin of these important strata. The southern parts of Lancashire, the northerfi extremity of Shropshire, and the whole of the intervening county o~" Cheshire, form in conjunction one vast tract of plain country, interrupted by few elevations,

Downloaded by [University of Toronto Libraries] at 23:23 04 June 2016 and these inconsiderable in size and extent. The area of this plain may be regarded as extending nearly fifty miles from north to south, and as having an average breadth of twenty-five or thirty miles. Its eastern boundary, as more immediately regards the county of Chester, is a high range of sandstone hills, stretching from north to south along the borders of Derbyshire and Staffordshire ; eonnected on t lrrom the Transactions of the Geo!oglcal Society, vol. i. the the Cheshire Rock-Salt District. ~11 the north with the hills in the West Riding of York, and on their eastern side passing into the limestone hills of Derbyshire. The sandstone, in a considerable part of this range, is shity in its structure, and would seem to belong to the Independent Coal-formation of Werner, some pretty extensive beds of coal being fotind and worked under it, The southern boundary of the plain., which is the one ap- proaching most nearly to the rock-salt, is irregularly formed by ridges of limestone and ealeareous sandstone, leaving open some eommunication~ with the level country in the middle of Shropshire. To the west its limits are marked by the sandstone and limestone hills in the adjoining part of Wales, and by tile sandy ~estuaries of the Mersey and Dee. The only ridge of hills, properly speaking, within the Cheshire plain ~, is one on the western side of the country, extending with a few interrnptions from to Mal- pas, and including in its progress from north to south, the hlgh. grounds of Delamere. .F°rest' the Hill. of Beeston, and the Peekforton Hills. This range, which no where attains an elevation of more than four or five hundred feel, is com. posed entirely of sandstone. A small quantity of copper ore has been found in the Peekforton Hills, which form its south.era extremity. Another ridge of land, possessing a small and irregular elevation above the adjoining plain, may be traced from the hills on the eastern border of Cheshire, in a westerly or north-westerly direction to Hahon and RuneQrn. ~xt this point, where it attains iis greatest height, it is separated from the northern extremity of the former ridge, only by the intervention of the valley of thg Weaver, whieh valley is here about ~wo miles iii width. Towards the eastern extremity of this range~ we meet with a singular sandstone hill, called , in which have been found ores of lead, copper and cobal b and masses of sulphate of barytes. This distribution of the high grounds in the Cheshire plain is traced out in the annexed map, and it will be seen,

Downloaded by [University of Toronto Libraries] at 23:23 04 June 2016 by a reference to thi% that they tbrm three distinct divisions ot" its area: one to the west of the higher sandstone range another to the east of this~ and south of the lower range ; and a third lying north of the latter, and including the southern parts ef Lancashire. With the exception of a very few instances only, the existence of the rock-salt" ap- pears to be exclusively confined to the southern or central plain. 0 ~ Yh¢ ~1~ .,4 Sketch of the _Natural History of The marl beds form the most peculiar feature in the aT- luvial strata of the Cheshire plain. These occur in great abundance in every part of the district; being found not only under the common soil, but occasionally, as on the borders of , interposed between layers of sandstone rock. The Cheshire marls are also very fre- quently met with in iarge detached masses, twenty or thirty feet in thiekness,.in the working out of which, it is not unusual to find large assemb!ages of fragments of the older rocks. Portions of granite, otten of large size, and show- ing on their surface evident marks of attrition, are among the most common appearances in these collections: no granitic rocks are found within fifty or sixty miles of this district. The divisions which I have pointed out in the Cheshire plain are still further marked by the course of the stream~ in this tract of country. The Dee is the great river of the western plain ~ the Weaver and its subordinate streams re- ceive all the waters of the southenl division; while the Mersey and its tributaries do the same in the northern por- tion. From their local relation to the great beds of rock- salt, the streams of the southern or central plain possess a peculiar importance. The Weaver rises in the Peekforton Hills, near the Shropshire border, runs for some miles towards the south- east, then making a sudden flexion to the north, continues in this direction, by and , to North- wich~ about thirty miles further. Here it takes a north- westerly course to Frodsham, where it expands into a sandy ~estuary~ connected with the channel of the Mersey. l't receives its principal accessions at , where it is joined by the united streams of the Dane and Weeloek fi'om the south-east, and by a stream called Witton Brook from the east. At Anderton, a little below Northwich, the valley~which has hitherto been comparatively wide and fiat, is suddenly contracted by the approach of two ranges of' high ground; that on the western side of the river con-

Downloaded by [University of Toronto Libraries] at 23:23 04 June 2016 necting itself by a .gradual rise with the heights of Delamere Forest j the opposite one passing by a series of irregular elevations into the range of high land, which separates the southern from the northern plain. _At Frodsham the river flows, as I before mentioned, between the termination of this high ground and that of the ridge which crosses the county from north to south, the hills thus opposed cor- responding perfectly in appearatlce amt ~tructure. We have the Cheshire Rock-Salt District. ~13 have thus two distinct contractions in'the valley of the Weaver below Northwieh ; a circumstance in some degree worthy of notice. Situation of the Brine Springs, Rock-Salt Mines, &e. I have dwelt thus minutely upon local facts from their connection with the situation of the rock-salt, which, with few exceptions, has vet been ascertained to exist only in the valleys of the Weaver and its tributary streams ; in some places manifesting its presence by springs impregnated with salt ; itr other places being known by mines actually carried down into the substance of the strata. A refereoce to the map will show the several situations where brine sprin~s occur, or where mines have been sunk, in the course of tl~se valleys. Between the source of the Weaver and Nantwieh, it will be seen that many brine springs make their appearance ; and in the latter part of this course, it would seem that brine might be obtained by sinking to some depth in any place near the banks of the Weaver. Proceeding down the stream, salt-springs occur again at Winsford, and in several situations between Winsford and Nurthwieh. .At Moulton, between these two places, a mine has been sunk into the body of rock-salt, and another also between ~Vinsford and . .At Northwieh the brine springs are very abundant, and here also many mines have been stank for the purpose of working out the fossil salt. The springs occur again in several places further down the river, but none have been met with below Sal- tersford, about two miles from Northwich. At Whitley, however, two miles north of the Weaver, and six miles from Northwich, a body of rock-salt is stated to have beert met with in boring for coal. On the course of the river Wheelock, brine springs have been found at Lawton, Roughwood, Wheelock, and aoain at Middlewich, where this stream unites itself with'the Dane. At Lawton a mine has been suuk into the rock- salt. In the valley of the Dane, no salt springs actually

Downloaded by [University of Toronto Libraries] at 23:23 04 June 2016 appear, but several circumstances indicate that briqe has at some former period been discovered there, and this as high up the stream as the neighbourhood of . No springs have been found in the valley of Witton Brook, except at the part of it immediately adjoining the Weaver at Northwieh. The evidences of the presence of rock-salt occur, as [ be- fore statedj iu very few places out of these valleys~ and even 0 3 some 214 Natural History of the Cheshire Rock- Salt Dis trlcj. some of the excepted instances appear to have a local rela., tlon to the south~!rn or central plain. This is the ease with the salt springs of Dirtwich, in the south-western angle of Cheshire~ with a spring of very weak brine lately found at kdderley, in the northern extremity of Shropshire; and robably also with other saline springs which occur in the contiguous parts of Flint and Denbighshire. At Dunham, however, in the north of Cheshire, we ill{el a weak spring, 'which cannot strictly be considered as connected with the formations of the southern plain. At Barton and Adling- ton, in the southern ~parts of Lancashire, brine springs' likewise appear ; and it is not improbable that other in. stances of the same kind may occur in the northern portion Of the great plato. It appears possible, however, that these weak springs may deri~e their saline .contents, not from distinct subjacent beds of the fossil salt, but merely from beds of clay or argillaceous stone, strongly impregnated With particles of the muriate of soda. .Manufacture of White Salt. It would be foreign to the object of this paper to etiter vcith minuteness into the natural history of the salt springs, or into the processes employed in th e manufaet/are of white salt. Those members of the Society, who may wish for i~ur~her information on these subjects, I beg leave to refer to the Survey of Cheshire before noticed. It may be suf- xqeient here to state a few of the most general and impor- iant facts. The brines met with in this district ~re very generally formed: by the t~enetration of spring or rain waters to the ~upper surface of the rock-salt, in passing over which they acquire a degree of strength, modified by several circum- stance% which it would be needless to detail. Their aver- age strength, however, appears to be much greater than that of the springs met with in Hungary, Germany~ or France. _At Wiiasford, Northwich, An~terton, Lawton~ l~oughwood,'Wheelock, and Middlewich, where all 'the

Downloaded by [University of Toronto Libraries] at 23:23 04 June 2016 principal s~/lt works are situated, the brine springs eontaizi between 25 and 26 pei" cent. oi: the pure muriate of soda ; apd in Sonic of the springs at Anderton, the proportion stands as high as 26"566 'per cent. a very near approach to ihe perfect saturation of the brine. Thd earthy salts held iO solution together with the muriate of soda are principally lmuriate of magnesia and sulphate of lime ; the quantity of these varyifig ttom ~per cent. to 2 or to 2{ percent, in dif- ferent On the Nautical Ephemeris. 215 ferent springs. The brine being pumped out of the pits, is first conveyed into large reservoirs, and afterwards drawn off as it is wanted, into evaporating pans, made of wrought iron. Here heat is aOplied in a degree determined by the nature of the salt intended to be manufactured, and various addifiojas are made to the brine, with a view either to assist the crystallization of the muriate of soda, or to promote the separation of the earthy salts. The latter exist in a very small proportion in the manufactured salt, and cannot be supposed m any degree to affect the uses to which it is ap- plied ~. The importance of the Cheshire salt manufacture will be sufficiently obvious from the statement, that besides the salt made tbr home consumption, which annually amounts to more than 16,0o0 tons, the average of the quantity sent to Liverpool ibr exportation has not been less than 140~000 tons. [To be continued.]

XXXI. On the Nautical Ephemeris, To 3Ir. 77lloch. SIR, A GREAT deal having lately been written and said about the error in the Nautical Ephemeris for 181c2~ but very little towards assisting the public in correcting this trifling mistake, I flatter myself some of your readers will not be displeased at having an easy and expeditious mode of correcting the Sun's Declination as given in the Ephe- meris; this being the part most affected by having as- sumed an erroneous apparent obliquity of the ecliptic ia the calculation of that work. The following small table of corrections I do not claim as my own ; I found it in the Connoissance des Terns for 181"2, where they also give the formula of its construction. The correction is for every third degree of declination, and for ol!e second of difference in the real and assumed obliquity of the ecliptic. All that is requisite to the ~ppli-

Downloaded by [University of Toronto Libraries] at 23:23 04 June 2016 cation of the tbllowing table is to multiply the tabular number b.y the difference between the real and assumed obliquity. The d~fferenee between the real obliquity and that as- sumed in the computation of the Ephemeris for 181~ is supposed to be about 8't too little. In referenceto the chemicalcharacter of the differentvarietie.~ of salt, an e~cettentpaper by my friend Dr. Henry will be found in the Philosophi- cal Tramattioxasfor the year 1810, part i. 0 4 TA~LR