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254 TRANSACTIONS OF THE GEOL. SOC. OF . effects were, perhaps, less powerfully felt in the neighbourhood of the Ben Leister Glen; the existing lines of fracture were easily acted upon by the subsequent convulsions; the solid claystones in the former fissures were rent asunder from the incompatible sandstones against which they rested, and the rapid flowing basaltic lava poured into every fissure and crevice that appeared. But, at that period, the now lovely Ben Leister Glen had no existence. A vast level pall of black lava was spread over the whole desolate surface of the land, and the last scene in the history of the Ben Leister claystones was the substitution of the gentle action of water for the desolating force of volcanic fires. The great sheet of lava was cut through: a deep glen was hollowed out in the sandstones that had been entombed below, and the phenomena we witness to-day in the depths of the glen, are probably only a fair sample of what exists throughout the whole of the foundations of the neighbouring hills.

XVI. On the CARBONIFEROUS SECTIONS of the LEVERN VALLEY, . By Mr. HUGH M'PHAIL.

(Read February 4, 1869.) Physicalfeatwes of the district—The Levern valley, in the south­ west of Renfrewshire, is bounded on the south by the trappean dis­ trict, which extends over the parish of Mearns and part of Neilston; on the north-west by the Fereneze range, and to the north it flattens out towards the undulating and knolly district south of Paisley. From its western extremity at Crofthead,it gradually opens out towards the Clyde, until it attains a width of more than 2 J miles from Waulkmill glen on the south, to Crookston Mains, where the carboniferous strata are interrupted by an igneous dyke which forms their northern boundary. A line between these two places across the districts of , , and Hurlet may be considered its eastern extremity. A ridge in the centre of the valley, extending from Ward- hill at its eastern extremity, to the west of , divides it into two portions, each having its own water-course; the Aurs water united with the Brock, in the southern; the Levern, in the northern. The ridge is formed of thick-bedded sand­ stones which crop out to the north, and are prominently exposed Downloaded from http://trngl.lyellcollection.org/ at Yale University on June 28, 2015

M'PHAIL—LEVERN VALLEY. 255 at intervals' throughout the valley. Kirkton burn flowing from Colinbar glen, crosses the valley diagonally at the western outcrop of the thick-bedded sandstones, and joins the between Cross-Arthurlie Works and Levern mill. These streams flowing from the high moorland districts in the south, over the trap formations above the valley, together with the various rivulets by which they are augmented, have exposed the various phenomena presented by the igneous and sedimentary rocks of the district. Throughout the valley and along the base of the traps, the physical aspect is indicative of the action of water similar to that observed in other districts in the valley of the Clyde. At the lower end of the valley, the Boulder clay is found in some places only a few inches in thickness, while in others it is raised into mounds, or deposited against northern escarpments, and where it has been deposited between disrupted strata, it has been found upwards of ninety feet in thickness. At Mtshill excellent oppor­ tunities are afforded of examining the Till as it is exposed in many of the quarries. Two-thirds of the boulders in it are of local origin, being composed of varieties of trap, ironstone, limestone, and sandstone, with smaller fragments of coal and clay-shale. The other third belongs to the older formations; they are much rounded, and a few of them slightly striated. In the neighbourhood of Barrhead there are numerous accumu­ lations, evidently fluviatile, or rewash from the Till, which must have been formed while the lower part of the valley was covered. The greater part of Grahamston, which is about 170 feet above sea-level, is built upon such deposits; but, as there have not been any recent excavations, I have neither had an opportunity of examining their nature, nor of determining if they contain any fossiliferous evidences. Carboniferous Strata.—The carboniferous strata come to the surface on both sides of the valley, from the trough in its southern portion. The trough is in a line with a point near the junction of the Aurs water with the Brock, and with Upper Arthurlie Works at the lower end of Colinbar glen, where it has been proved in the coal-workings. It seems at some places to be thrown a little out of the above line by transverse dislocations, one of which crosses it from South Arthurlie to Cross Arthurlie, and evidently causes a slight change of the basin, but in a general view this line may be considered as marking its position. The strata lying Downloaded from http://trngl.lyellcollection.org/ at Yale University on June 28, 2015

256 TRANSACTIONS OF THE GEOL. SOC OF GLASGOW. contiguous to the trap along the south of the valley, and dipping to the trough, are found along the ridge which divides the valley, as they crop out to the north; and in conse­ quence, the beds on the north side of the ridge, are lower in the carboniferous series than those exposed on the south. The strata on the north side gradually thin.out, until the Hurlet main coal crops out at "West Hurlet, and also between and Blackbyres. Near Townhead a small coal was reached about eleven fathoms below the Hurlet main coal. This coal is about eighteen inches in thickness, and is the lowest stratum which has been reached in the valley. It was also found in the workings of the Nitshill and Lesmahagow Coal Company at Nitshill. The cross section of the valley (given in the accompanying woodcut, page 257), represents the manner in which the strata are found from Waulkmill glen to the igneous interruption at Crook- ston Mains, and embraces more than three hundred fathoms, from the Hurlet and Campsie series upwards to a brown sand­ stone1 in the southern portion of the valley, the position of which I consider to be about twenty fathoms above the Garnkirk lime­ stone. Taking the principal beds in descending order from this sandstone, they are found as follows :—

Journal of Strata exposed during the working of the Nitshill Quarries.

Feet. In. Feet. In. Sandstone, at its outcrop. Clay shale, with ironstone Coal, - 0 10 nodules, -- 3 0 Sandstone, highly siliceous, 7 0 Oil shale, - -- 0 8 Do. flaggy, - 3 0 Coal, -- 0 10 Clay shale, 2 0 Clay shale, with ironstone Sandstone flags separated by nodules, -- 3 0 shale, - 13 0 Coal, -- 1 6 Sandstone,2 26 0 Clay shale, -- 1 8 Coal, - 1 2 Sandstone, - - 15 0 Sandy shale, 3 4 Shale, - - 0 10 Coal, 10 1 Along the trough from Little Auchinback to near Darnley House lies the above sandstone, terminating abruptly at both ends of the bed, particularly that next Darnley House, where it is seen lying

11 would be inclined to consider this sandstone the equivalent of the mill­ stone grit, if its existence be admitted in .

2 m There is a part of this bed, averaging about six feet in thickness, highly siliceous, which causes much trouble and expense in the working of the quarries. Downloaded from http://trngl.lyellcollection.org/ at Yale University on June 28, 2015

CROSS SECTION OP LEVERN VALLEY FROM WAULKMILL GLEN TO CROOKSTON MAINS.

a, Outcrop of the thick-bedded sandstone on the south of the valley; /, Outcrop of the thick-bedded sandstone to the north, and where it forms the ridge in the centre of the valley; b, Fault seen in Waulkmill Glen ; c, Junction of the Aurs with the Brock ; d, North Brae, or Arden limestone cropping to the north; e, The great fault in the centre of the valley; g, Fault running from towards Boghall; h, Horizon of Nitshill sandstone beds; i, Fault between Nitshill and Hurlet sections; j, bed of the Xevern; Is, Outcrop of Hurlet main coal series, with intrusion of igneous rocks. Downloaded from http://trngl.lyellcollection.org/ at Yale University on June 28, 2015

258 TRANSACTIONS OF THE GEOL. SOC. OF. GLASGOW. upon a thick bed of clayey and calcareous shales, which separates it from the limestone locally known as the "North Brae" limestone. Entering Waulkmill glen from the junction of the Aurs water with the Brock, the above shales are well seen, the stream having worn considerably into the rising ground forming its west bank. The upper thirty feet of these shales is a com­ plete mass of nodules; towards the centre they are more clayey, but gradually become calcareous and fossiliferous as they approach the limestone. Further up in the bed of the stream the lime­ stone, whieh has been much wrought in the vicinity of the glen, crops out from under the shales. At a depth, which varies from three to five fathoms from the limestone, there is a " splint" coal of inferior quality, known in the district as the "North Brae" or Auchinback coal, it having been extensively wrought on the grounds so named. The workings were all near the outcrop, the coal varying from three to three-and-a-half feet'in thickness. About a hundred yards from the junction of the Aurs with the Brock, this coal was reached at about eighteen fathoms, being considerably in the dip of the other shafts, and from three to five feet in thick­ ness, gradually becoming thicker towards the trough. It agrees in every respect with that found at Shirva and Kirkintilloch. Continuing up the glen, the outcrop of the coal is traceable along the edge of the stream as it winds round a knoll, and nearly in a straight line for about one hundred yards, when, by a fault, the limestone and the coal are thrown off. This fault is caused by an upthrow to the south, but from surface investi­ gations, it is impossible to determine accurately its extent; but as the coal has been wrought west from the glen on the upper side of the fault, and from the angle at which the strata lie towards the glen, it is probable that it cannot be more than from twelve to fifteen fathoms. The connection of the strata lying above the fault, as seen in the Darnley old reservoir, with those of the upper part of the glen, which is a deep ravine, is cut off from view, by the surface soil having slid over at its lower entrance. The strata in the ravine are cut through to the depth of seventy feet as they are tilted up against the trap lying above the glen, expos­ ing a vertical section of nearly forty fathoms. Near the centre there are two beds of limestone, ten and twenty-two inches thick respectively, separated by about three inches of shale, with about three inches of coal under the lower bed. This limestone is Downloaded from http://trngl.lyellcollection.org/ at Yale University on June 28, 2015

M'PHAIL—LEVERN VALLEY. 259 known as the " Lyoncross" limestone, it having been wrought at a small ravine of that name. About three fathoms under this limestone there is a soft coal, averaging about eighteen inches, known as the "Lyoncross" coal, and, like that of North Brae, it has been extensively wrought in the vicinity, the workings from this ravine having been connected with those at Lyoncross. Immediately under the Lyoncross coal are the thick-bedded sandstones, seen at the top of the glen, and which are about ninety feet thick. The embankment of the Water Works reser­ voir is upon this sandstone, the under stratum of which crops out in the bottom of "the reservoir from under the embankment; and from under the sandstone, also in the bottom of the reservoir, there is seen a bed of limestone cropping out quite contiguous to the traps of the higher district. This limestone, which is the under­ most stratum of any consequence exposed in the section, is best seen east of the tower in the reservoir, and serves as a good index in identifying the section with others in the neighbourhood and around Glasgow, it being identical with that of , Possil, and Robroystone. Prom the middle of the trough to the ridge in the centre of the valley, there are no strata exposed with the exception of the North Brae limestone, which is at present being wrought near Dam- ley toll-bar. It was also wrought at Dovecothall in a line with Darnley Lime Works, and nearly parallel with the ridge in the centre of the valley. The Auchinback coal, lying from three to five fathoms under the limestone on the south of the trough, was also wrought near the surface at Darnley and Dovecothall, and as these strata come into position so near the ridge formed by the thick-bedded sandstones, it is evident, from the absence of the strata lying between them and the sandstones, that there must be a fault causing a displacement of at least sixty fathoms, by which the latter are elevated to the surface together with the Auchinback section. This fault is seen in the railway cutting near Nitshill, where there is a good section laid open, showing the Lyoncross coal and limestone with the thick-bedded sandstones. Near Dye wood mills, where the strata rise from the basin at Darnley, the Nitshill and Lesmahagow Coal Company in their workings, found this displacement to be forty-one fathoms, thereby proving its agreement with the surface phenomena. The same Company drove a mine in the coal about 300 yards from the fault, Downloaded from http://trngl.lyellcollection.org/ at Yale University on June 28, 2015

260 TRANSACTIONS OP THE OEOL. SOC. OP SCOTLAND. at a distance of about 250 fathoms below the surface, the coal being fully its average thickness. There is a strip of the Lyoncross coal on the top of the thick- bedded sandstones, lying between them and the fault, as observed in the railway cutting; it was wrought at Boghall quarry, and was also found in a well at Parkhouse farm. In a shaft sunk at Wardhill from the top of the ridge through the sandstones, and at the depth of fourteen fathoms, the limestone was found in the same position as under the sandstones in the Waulkmill glen reservoir; and on the Slates farm other two. shafts were sunk, in both of which a limestone was found which was considered to be the Auchinback limestone; but as the fault runs between the two shafts, only the limestone found in the shaft south of the fault can be that of Auchinback, and the other must be the limestone lying under the thick-bedded sandstones. The Boghouse coal, wrought by the Nitshill Ironwork Company about twenty-five years ago, lies under the above-mentioned sand­ stones and limestone, at a distance which has not been determined, as their shaft was sunk off the outcrop of the limestone. Boulder clay, deposited between the sandstones and a fault a few yards to the north of the shaft, was sunk through to the depth of about fourteen fathoms. On the north side of this fault are the Nitshill sandstone beds, and between them and the above sandstones there is a hollow caused by the dislocation, which is filled up with the drift to the above-mentioned depth. This fault, by which the Boghouse coal is thrown out to the north, runs in a line from Priesthill, between the Alum works and the quarries at Nitshill, towards Boghall. The late Mr, Dugald Dove, of Nitshill, while driving a mine in one of his quarries came upon it, and the Nitshill and Lesmahagow Coal Company have found it in their workings about 200 fathoms below the surface, to cause an up­ throw of twenty-five fathoms to the north. The excavations of the Nitshill quarries are close upon the fault, and during the progress of the workings a vertical section of about ninety feet has been cut, a journal of which is given with the cross section of the valley. The Nitshill or Satterland coal, which is the undermost stratum of the quarry section, was passed through in sinking the Victoria pit. Unfortunately, a journal was not kept, but in it, about two fathoms under the above coal, there is a twelve-inch Downloaded from http://trngl.lyellcollection.org/ at Yale University on June 28, 2015

M'PHAIL—LEVEBN VALLEY. 261 coal separated from another under it, sixteen inches in thickness by about seven feet of shale and ironstone nodules. Under these coals there are thick beds of shale and sandstones—the shale predo­ minating—and containing numerous thin bands and nodules of ironstone. At the depth of forty fathoms there are several thicker bands, the two thickest being ten and six inches respectively, and with the exception of two small seams of coal, there is nothing but the thick-bedded shales and sandstones, until "Lillie's" coal is reached at one hundred fathoms. This coal is here two-and-a- half feet thick, eight inches of the bottom of it being a good cannel coal, yielding a fair per centage of oil when distilled. From Lillie's coal to the bottom of the shaft, the strata are concealed by the woodwork supporting its sides. This shaft is 175 fathoms from the surface, to the Hurlet and Nitshill main coal, which averages five-and-a-half feet in thickness. There is found at intervals, lying above the coal in this pit, a black-band ironstone, varying from three to six inches, locally known as "panel," which yields about thirty- three per cent, of pure metallic iron. Above it is the alum shale, varying from one inch to seven feet in thickness, succeeded by the well-known Hurlet and Campsie limestone, varying from two to three-and-a-half feet in thickness. Over the limestone there are five feet of clay-shale, which yield a large supply of alum by the " sul­ phuric acid" process. The strata have been cut through in this pit, to the depth of eleven fathoms below the main coal, to the eighteen-inch coal previously mentioned, and the strata between them consist of clay-shale with ironstone nodules and several thin bands of lime­ stone. The Hurlet section is elevated above that of Mtshill by an upthrow of about forty fathoms. In the Nitshill workings the coal is found continuing some distance up the fault at its average thickness, and upon the Hurlet side it is found to continue down­ wards, consequently there is a prevailing opinion that there is no fault, but that it is an abrupt bend of the strata which separates the two sections. When the thickness of the strata, however together with the distance between the point in the Mtshill section, where they leave their ordinary angle, and the point in the Hurlet section at which they resume it, is considered, it is quite evident there must be a fault, as shown in the cross section. Entering upon the Hurlet section, tho first stratum observed is a yellow fissile sandstone on the south of Levernholme. On the top Downloaded from http://trngl.lyellcollection.org/ at Yale University on June 28, 2015

262 TRANSACTIONS OF THE GEOL. SOC. OF GLASGOW. of this sandstone there are two thin bands of limestone separated by two or three fathoms of shale; and a few feet above the upper band lies LilhVs coal which crops out at Househillmuir. There are no strata exposed between the sandstone in Levern- holme and Hosie's limestone series, which is seen in the bed of the Levern at Bough-mussel. The limestone is in four beds of about nine inches each in thickness, separated by about the same thickness of shale. A few feet under the limestone there are four beds of clayband ironstone, the two uppermost about four inches, and the other two varying from ten to twelve inches each in thickness. The two middle bands have been exten­ sively wrought, but the undermost, which is about seven feet below the others, was not known until the others were nearly wrought out in the Hurlet section; and when the bottom band, which is from ten to twelve inches, was found, it could not be easily wrought for want of roofing, the distance between it and the old workings being so little. Further down the Levern, on the south bank, there is exposed a good section of the thick-bedded shale with its ironstone nodules, passed through by the numerous shafts in the district which have been sunk to the clayband ironstones and the main coal. And still further down there is a clayband ironstone ten inches in thickness seen cropping out in the bed of the stream. This band has not been wrought, but must have been passed through in several shafts put down to the other ironstone beds, which lie about fifteen fathoms below it. The Main coal series is seen at the opening to the Hurlet work­ ings in the Baes wood. The strata at the outcrop are thinned out very much, but are well seen in their true position. This series at Crookston Mains is interrupted by an igneous dyke visible at the surface, and the contiguous strata are much altered by the agency of heat. The coal is converted into a compact, coke-like substance, locally known as " Grey Maggie," and contains a large percentage of lime, evidently due to water passing down through the partially calcined limestone which overlies it. Close upon the dyke the coal and lime are found run together and con­ solidated in a mass. For more than fifty yards from the dyke the heat must have penetrated the strata downwards, as in the pit, the charred coal is found next to the roof, gradually becoming thicker towards the dyke until the whole bed is found charred Downloaded from http://trngl.lyellcollection.org/ at Yale University on June 28, 2015

M'PHAIL—LEVERN VALLEY. 263 through. These evidences show that there must have been a flow of igneous matter along the surface which has since been almost completely denuded away. As the valley narrows towards the west, the strata attain a high angle, and are gradually thrown off. At Grahamstown the Hurlet series is seen to be tilted up at a great angle, and to abut against the trappean ash at the base of the Fereneze range. At West Arthurlie the Boghouse coal, known there as the " Barrhead" coal, has been extensively wrought. On the top of the thick-bedded sandstones, seen along Craigheads and at the back of Kelburne Street, Barrhead, and forming the ridge previously mentioned, lies the Lyoncross coal; and on the opposite side of the trough in the glen at South Arthurlie Works, the limestone and coal lie immediately on the top of the sandstones in a line with, and as seen in Waulkmill glen. The Lyoncross coal was wrought in this glen from side openings which are still to be seen. As the trough narrows towards its termination near Wraes mill, the beds in Colinbar glen attain an angle of 25°. From Bar- shagra, and parallel with Lochlibo road, they dip in opposite direction from those which crop out from the trough of the valley, the dip being towards the Levern, in the bed of which the strata are found dipping in all directions, and narrowing to a point where the traps on both sides of the valley join near Broadley Mill. The Hurlet series extends east to the junction of the Brock with the Levern at Haugh, where it is interrupted by a downthrow, on the east side of which the strata rise towards , where the dip is seen to change towards the Clyde. The "Hosie" limestone series in this district has associated with it the bituminous oil shale, mentioned by Mr. John Young as found at the South-hill Campsie,1 but the limestone here having been formed at four different periods, shows that elevations and depressions have taken place, or that a clayey sediment has been deposited in this locality, while that north of the Clyde enjoyed undisturbed deep water, the same bed being there one continuous formation of about six feet in thickness. The sandstone at Levern- holme, with the limestone above it, appears to be identical with that at Barriston, both being about thirty fathoms above the Hosie

1 Trans. Geol. Soc. Glasgow, Vol. I. T Downloaded from http://trngl.lyellcollection.org/ at Yale University on June 28, 2015

264 TRANSACTIONS OF THE GEOL. SOC. OF GLASGOW. limestone. It is more than probable that the blackband ironstone, at present being wrought to the north and north-west of Paisley, has been passed through unnoticed in several shafts in this district, as it is unlikely that it is altogether absent, since the strata below, as well as those above its position, are identical with those near Paisley. Its positionis between Lillie's coal and Hosie's limestone. The shafts to the clayband ironstone of the Hurlet series at Inkerman, near Paisley, pass through Lillie's coal and the black- band ironstone. The Nitshill series lies into the Oowglen series, and is separated from its north-eastern section by a seventeen fathoms down-throw. The "stone" coal in the Cowglen section consists of two beds of coal, ten and twelve inches respectively, separated by about ten inches of stone, and is identical with that seen a few fathoms down the Victoria pit shaft, where it is twelve and sixteen inches of coal, separated by seven feet of shale and ironstone nodules; but further west at Satterland the coals are only a few inches thick and sepa­ rated by a few inches of "stone." The " sclutty" coal of Cowglen is identical with that known at Nitshill as the " Boghouse." The series in the southern portion of the valley extends towards and , the Northbrae limestone being wrought at Thornliebank, where it is well known as the " Arden " limestone. The Lyoncross limestone crops out at Orchard and Williamwood, where it is known as the " Orchard Cement Stone." It was also found above the thick-bedded sandstones in the railway cutting at Pollokshaws. The sandstones are here seen to dip at a high angle towards Eastwood, and to re-appear at Giffhock, having the lime­ stone under them as at Nitshill, and in "Waulkmill glen reservoir. There seems to be a deficiency of strata on this side of the Clyde basin, as in Mr. William Moore's section of the strata of the Lanark­ shire coal-field, the Garnkirk limestone is stated to be 395 fathoms above the Hurlet and Campsie Main limestone, and the distance between these limestones in this district is found to be about 310 fathoms as follows:—From the Hurlet and Campsie limestone to Cowglen stone coal, as found in the Victoria pit shaft, is 170 fathoms; from the Cowglen stone coal to the thick-bedded sand­ stones, as found near Cowglen, and about 1000 yards from Victoria Pit, is about sixty fathoms; from the bottom of the thick-bedded sandstones to Lyoncross limestone is about twenty fathoms; and the great fault by which the Darnley or Auchinback limestone is Downloaded from http://trngl.lyellcollection.org/ at Yale University on June 28, 2015

M'PHAIL—LEVERN VALLEY. 265 brought to a level at the surface with the Lyoncross limestone and the thick-bedded sandstones, is about sixty fathoms. The four great faults shown in the cross section, which traverse the valley in a direction nearly east and west, are intersected by smaller faults at various angles. These have produced upthrows of the strata to the westward, and indicate either that the strata towards the west have been upheaved, or that a subsidence has taken place near Darnley, where is now the basin of the valley. The natural formation of the trough, as proved in the coal work­ ings at Barrhead and Waulkmill glen, shows that the various depositions have taken place at an angle towards the horizon on both sides of the basin, and the uniform thickness of the sedimen­ tary beds, as seen tilted up against the trap on both sides of the valley, also shows that they must have been deposited at a lower angle than that at which they are now seen. It will be observed from the cross section that the faults which traverse the valley cut the strata at an angle from both sides towards the centre of the trough, thus causing the strata to assume a wedge-like form between the great fault in the centre of the valley and the fault on the south of the trough. The great fault was found continuing at the same angle at a depth of about 250 fathoms. It would therefore appear that the faults could not have been formed by a depression of the valley, but that they must have been caused by the elevation of the traps; and the other evidences tend to confirm this theory. From Broadley mill to Barshagra the strata are found dipping in various directions; from Barshagra to Grahamstown they are tilted abruptly against the traps, and between Grahamston and Townhead farm the Hurlet series is found almost perpendicular. At Boylstone there is a bed of sandstone1 lying between the traps and the Hurlet series, and at a different angle from the adjacent strata.* Between Boylstone House and Crosstobs there is a bed of limestone2 dipping towards the trap range. There are also two beds, or portions of one bed, of hard white sandstone tilted into an almost perpendicular position at the base of the traps, in a line with Boylstone House and Brownside glen, where another change is observable. On the hill-side above Brownside House a strip of the strata is found identical with that seen in the lower-lying

1 This sandstone was nearly all quarried away during the construction of the railway. 2 The limestone was wrought here, and the kilns are but recently removed. Downloaded from http://trngl.lyellcollection.org/ at Yale University on June 28, 2015

266 TRANSACTIONS OP THE GEOL. SOC. OF GLASGOW. district at Holybush. Continuing round the base of the range another change is seen at Glenfield, where there is a sandstone upon the hill side of the road, similar to, if not identical with, that at Boylstone; and upon the other side of the road is a hard dark coloured sandstone traceable east to Oldbar, where it seems to dip under the Hurlet series. Where the Hurlet and Campsie series is seen in the bed of the Levern tilted up against the trappean ash at the base of the Fereneze range, is about 150 feet above sea- level, and as the range slopes down towards the west under the Ayrshire coal-field, the same series is found in the Parish of Beith, about 412 feet above sea level. The distance is about two miles from the point in the Levern valley, where the carboni­ ferous strata are cut off by the traps, to the point where they re-appear near Shillford,' and where they are continuous with the Ayrshire coal-field. The trap range, near Shillford, attains an elevation of about 850 feet above sea-level, and about 450 feet above the carboniferous strata at the same place. The difference in relation to the sea-level of the position of the Hurlet series on both sides of the range, and at points so near to each other, together with the other evidences seems to affirm that the range has been elevated, and has thereby separated the carboniferous strata of the valley of the Clyde from those of Ayrshire. Indeed, this range would seem to have been elevated considerably above its present height, and when again depressed to have carried down with it the strata, as seen at Gateside and near Broadley mill. This hypothesis would also account for the position in which the sandstone is found at Boylstone, between Boylstone and Brown- side glen, and also for the limestone between the latter and Crosstobbs. The various geological phenomena along the base of this range cannot be accounted for by the theory, that the traps, as they there exist, are of anterior date to the carboniferous strata, and that these strata have been deposited against them. If we suppose that the above range has been elevated, which may have taken place contemporaneously with the volcanic eruptions in the valley, of which there are evidences at Hurlet, as previously mentioned, and also between Blackhall and Hawkhead mills, it would appear that prior to the elevation, and the conse­ quent displacements, that the carboniferous strata had extended from the trap range near Bishopton on the north, to the traps south of the Levern valley; and this supposition might also Downloaded from http://trngl.lyellcollection.org/ at Yale University on June 28, 2015

M'PHAIL—LEVERN VALLEY. .267 account for the geological phenomena in the Johnstone district. By whatever causes these great displacements have been occasioned, whereby the northern portion of the valley has been elevated to its present position, it must have been since subjected to extraordinary denudation, as it is now at a lower level than that of the southern. And if we suppose that the upper strata of the southern portion extended as far north as Hurlet previous to the displacements, there must have been upwards of 1,500 feet denuded away from above those now forming the bed of the Levern, near Hurlet. After the elevations, the bold escarpments formed would probably be directly in front of the denuding agent, as suggested by the glacial striss at Old- bar and Crosstobs, to which they would soon give way on account of the thick beds of clay shale of which they were composed. At the western extremity of the valley the glacial striae are found high on the hill side due east and west, as well as in the recent railway excavations, showing that by this outlet between the traps, had flowed the denuded debris. The origin of the sand­ stone boulders found to the westward of the Levern would thus be accounted for. Trappean series.—The rock-masses forming the various members of the trappean series within the Levern district, are similar in character and mineral composition to tjiose found in other tracts of the Renfrewshire trap hills, and evidently belong to the same periods of igneous activity. At various points along the range, it is seen that the lower part of these hills, consist of greenish-grey, and reddish-brown beds of volcanic ash, which are succeeded by amygdaloidal and compact felstones of various colours. Fine grained greenstones and felstone porphyries compose their higher parts. Zeolitic and other minerals are found in the trap at various points, some varieties of which are much prized by collectors. At Boylstone quarry, near Barrhead, fine specimens of Prehnite of a rich green colour are obtained. This green colour is due to the surface of the mineral being coated with green carbonate of copper, which is also found upon the Prehnite in the form of small round mammilated crystals. Native copper is also found here in thin sheets, lining fissures and cavities in the trap. It is not very abundant, specimens have, however, been found at intervals, weighing several ounces. Na­ tive copper is of very rare occurrence in Britain, having only been found in a few localities. Downloaded from http://trngl.lyellcollection.org/ at Yale University on June 28, 2015

268 TRANSACTIONS OF THE GEOL, SOC. OF GLASGOW.

Analcine, coated with minute crystals of copper-coloured iron froth, which gives the mineral a beautiful appearance, is also found in Boylstone quarry, along with specimens of Thomsonite and other zeolites, the latter, however, are of rare occurrence in this part of the district.

LIST OF CARBONIFEROUS LIMESTONE FOSSILS FOUND IN THE VALLEY OF THE LEVERN. PLANT JE.

Species. * Localities. Lepidodendron elegans, Brongn. Nitshill. Sigillaria organum, Lindley. Do. Sphenopteris bifida, Lindley. Do. Ulodendron minus, Lindley. Do.

ZOOPHYTA.

Zaphrentis patula, M. Edw. Nitshill.

ECHLNODERMATA.

Actinocrinus, sp.? Orchard. Archaeocidaris Urii, Flem. Nitshill. sp.? Orchard. Hydreionocrinus glohularis, De Kon Do. Poteriocrlnus crassus, Miller* Do.

ANNELIDA. Serpulites membranaceus, M'Coy Arden.

CRUSTACEA.

Bairdia curta var. plebeia, MfGoy Orchard. subcylindrica, Munster. Do. Leperditia Okeni, MUnster. Do. Cythere cuneola. Do. cornigera, Jones and Kirkby Do. ventricornis, JonesandKirkby Do. sp,? Do. Beyrichia bituberculata, MlCoy. Do. Kirkbya radiata, Jones and Kirkby Do. — Permeana, Jones. Do. . —bipartita, Jones and Kirkby Do. symmetrica, Jones ds Kirkby Do. Downloaded from http://trngl.lyellcollection.org/ at Yale University on June 28, 2015

MfPHAIL—LEVERN VALLEY.

Dithyrocaris testudineus, Scouler. Orchard. Estheria punctatella, Jones. Arden. Griffiithidesmeso-tuberculatiiSjif'Coy Orchard. Eichwaldi, Fisch. sp Do.

BEACHIOPODA. Athyris ambigua, Sow. Orchard and Arden. plano-sulcata, Phill. Arden. Chonetes Hardrensis, Phill. Orchard and Arden. Crania quadrata, M'Coy. Orchard. Discina nitida, Phill. Do. Lingula mytiloides, Sow. Orchard and Nitshill. squamiformis, Phill. Arden. Orthis resupinata, Martin. Orchard. Productus cora, D'Orb. Arden. costatus, Sow. Orchard. giganteus, Mart. Do. latissimus, Sow. Arden. longispinus, Sow. Do. Martini, var., Sow. Do. mesolobus, Phill. Do. punetatus, Mart. Do. scabriculus, Mart. Do. semireticulatus, Mart Do. and Orchard. Youngianus, Davidson Orchard. Rhynchonella pleurodon, Phill. Arden. pugnus, Mart. Do. Spirifera bisulcata, Sow. Do. and Orchard. duplicicosta, Phill. glabra, Mart. Orchard. lineata, Mart. Do. and Arden. Urii, Flem. . Nitshill. Spiriferina var. octoplicata, Sow Arden. Streptorhynchus crenistria, Phill. Orchard. « var. radiahs, Phill Do. Terebratula hastata, Sow. Arden.

LAMELLIBRANCHIATA (MONOMYARIA). Aviculo-pecten arenosus, Phill. Mtshili. Pinna flabelliformis, Mart. Arden. Pteronites, sp.? Do. Downloaded from http://trngl.lyellcollection.org/ at Yale University on June 28, 2015

270 TRANSACTIONS OP THE GEOL. SOC. OF GLASGOW.

LAMELLIBRANCHIATA (DIMYARIA).

Area Lacordaireana, De Kon. Orchard. Axinus axiniformis, Phill. ... Nitshill and Orchard. Cypricardia acuticarinata, Armstrong Orchard. rhombea, Phill. Do. Leda (Ctenodonta) attenuatum, Fl Do. longirostris, M(0. Do. acuta, Sow. Do. sp. Do. sp. Do. Leptodomus costellatus, M'Coy. Nitshill. Myalina crassus, Flem. Do. Verneuillii, MlGoy. Do. Nucula gibbosa, Flem. Orchard. luciniformis, Phill. Do. Sanguinolites iridinoides, M'Coy Do. Venus, sp.? Do.

GASTEROPODA.

Chiton, sp. ? Kirhby and Young, Geol. Mag., vol. iv. p. 340, pL xvi. f. 7 a, b, c, 9. . Williamwood. Dentalium priscum, Goldf. ..Orchard. Eulima Phillipsianus, De Kon. .. Do. Euomphalus pentangulatus, Soio. .Arden and Nitshill. carbonarius, Sow. .Orchard. Loxonema, 2 sp. .. Do. scalaroidea, Phill. . Do. Lef ebvrei, L EveilU. . Do. Macrocheilus imbricatus, Sow. .. Do. Michotianus, De Kon. . Do.

# sp9 . Do. Murchisonia, sp. . Do. striatula, De Kon. . Do. Pleurotomaria Frenoyana, De Kon. . Do. monilifera, Phill. . Do. Yvanii, L. EveilU. . Do. 2 species. . Do. Trochus conifonnis, De Kon. Arden. Downloaded from http://trngl.lyellcollection.org/ at Yale University on June 28, 2015

#RAfG—CARBONIFEROUS BASIN OF DALRY. 271

GASTEROPODA (NUCLEOBRANCHIATA). Bellerophon decussatus, Flem. Orchard. Dumontii, D'Orb. Nitshill. striatus. Do. and Orchard. Leveilleanus, De Kon Orchard. TJrii, Flem. Do. and Nitshill.

PTEROPODA. Conularia quadrisulcata, Sow. Wauk Mill glen.

CEPHALOPODA. Actinoceras giganteum, Sow. Arden and Orchard. Cyrtoceras rugosum, Flem. Orchard. unguis, Phill. Do. Goniatites striolatus, Phill. Do. excavatus, Phill. Nitshill. vesica, Phill. Orchard. Nautilus ingens, Mart Arden. subsulcatus, Phill. Orchard and Nitshill. globatus, Sow* Orchard. Orthoceras attenuatum, Flem. Do. and Nitshill. subcentrale, De Kon Orchard. undatum, Flem. Arden and Nitshill.

PISCES. Cochliodus magnus, Ag. Arden. Megalichthys Hibbertii, Ag. Hurlet. Psammodus porosus, Ag. Arden. Rhizodopsis minor, Ag. Orchard.

XVII. Sketch of the CARBONIFEROUS BASIN O/DALRY, AYRSHIRE. By BOBT. CRAIG, , Beith, Corresponding Member, Geological Society of Glasgow.

(Head January 7, 1869.) THE part of North Ayrshire to which the following remarks refer is generally known, geologically, by the name of the Dairy basin. It has an area of nearly thirty square miles of carboniferous strata, is of a triangular form, and lies in the parishes of Dairy, Kilbirnie, and Beith. The south-west angle extends into the north of Kil-