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MACGREGOR—THE GARRIONGILL SECTION AT OVERTOWN. 279

No. XI.—THE GARRIONGILL SECTION AT OVERTOWN, NEAR .1 By M. MACGREGOR, B.Sc.

[Read 14th March, 1912.]

THE object of this paper is to describe in detail a natural section in the Upper Carboniferous of the West of that has been somewhat neglected by geologists. The Garrion Burn lies, roughly, l£ miles S.W. of Wishaw, and is easily accessible from Glasgow by train to Overtown or to Law Junction. It was mapped on the 6-inch scale by the Geological Survey of Scotland in 1869-70 (see published 6-inch sheets of H.M. Geological Survey of Scotland, , 18 N.E. and S.E.), but no account of the section has so far been published. The Garrion rises near Bentyhillocks on the S.W. edge of Auchterhead Muir, and enters the Clyde opposite Dalserf. For the first few miles it pursues a winding course among boulder- clay drumlins, and only at one point exposes a section worthy of particular remark. This is at Hyndman Bridge, where a little rock is seen the stratigraphical position of which lies about the base of the Coal. Measures. It is not, however, until the burn reaches the sharp S.W. bend just N. of Gillhead Farm that it leaves the boulder clay and enters on the long rock section described below. From this point to Garriongill Bridge, near the Clyde, there is a fairly complete section of the strata lying between the Kiltongue Coal and a horizon approxi­ mately 50 to 53 fathoms above the Ell Coal of .

1. Kiltongue Goal.—This is exposed on the left bank of the burn slightly west of south of Garrion Burn Cottage. The full thickness is not seen, but the coal was worked at the crop here during the recent strike, and over 2 feet 8 inches exposed. From bores in the immediate neighbourhood the average thick­ ness in the ground to the north is 2 feet Hi inches, and in the ground lying south of the burn 3 feet 6 inches. The Kiltongue

1 Communicated by permission of the Director of H.M. Geological Survey.

VOL. XIV., PT. HI. U Trans. Geol. Soc. of Glasgow. Vol XIV, Plate XXXII.

/ Dye /?rxHsec£

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JPyOtKSJzAW &XZZ. Downloaded from http://trngl.lyellcollection.org/ at University of Saskatchewan on March 14, 2015

280 TRANSACTIONS GEOLOGICAL SOCIETY OP GLASGOW.

Coal here is a clean uniform seam of bright coal, producing a house fuel of excellent quality.

2. Strata between Kiltongue Mitsselband and Kiltongue Goal.—These strata are seen in small exposures just east of Gillhead Bridge2 and (less completely) west of Garrion Burn Cottage. The section is as follows: — Feet. Inches. Fireclay, blaes, and ironstone balls, 3 6 Sandstone and fakes, 10 0 Blaes, ..... o 10£ Ironstone rib (persistent) up to, 0 If Blaes and ironstone ribs, 2 3 Fakes (not well seen), - about 4 6 Blaes and ironstone ribs, 2 7 Probable gap, .... 3 0 Fakes, ----- 2 6 Sandstone, - 1 0 Fakey blaes, with irregular sandstone ribs, 5 1 Dark blaes, - 0 3 Kiltongue Coal—base not seen.

The total thickness is 6 fathoms 1 foot 8J inches, but the section is pieced together from four different exposures, and cannot be quite satisfactory. The average thickness in eight neighbouring bores is 6£ fathoms, and the strata met with are mainly sandstone and fakes, with a few feet of blaes, often containing a thin coal seam in the middle; this agrees fairly well with the section given above.

3. Kiltongue Musselband.—This horizon forms a valuable index throughout Lanarkshire. At four different points in the Garrion excellent sections are exposed. The most easterly of these lies 117 yards east of Gillhead Bridge, and shows the following: — Feet. Inches. Tough shale (cannel), .... ? Musselband, ----- 0 9^ Ironstone, - - - - - 0 1J Dark fireclay, ----- ?

2 This and other place names mentioned are taken from Ordnance Survey 6-inch sheets. Downloaded from http://trngl.lyellcollection.org/ at University of Saskatchewan on March 14, 2015

MACGREGOR—THE GARRIONGILL SECTION AT OVERTOWN. 281

The beds here have a slight dip up stream, and the ironstone can be followed from the point where it crosses the burn for 30 yards westward along the left bank. It is again finely exposed in several sections, near old Garriongill Mill.3 Section A, on railway embankment above burn, 60 yards or so east of the mill— Feet. Inches. Sandstone, - - - - - 6 0 + Dark blaes, .....] ,5 Tough cannel-shale, with fish teeth, - - 0 5 J Musselband, ----- 0 9 Ironstone, - - - 0 ft. 1 in. to 0 2

Section B, at old eye on right bank, at mill— Feet. Inches. Thick sandstone, .... ? Dark blaes (with plants), 1 (Local) Ironstone, full of "mussel" shells, 0 ins. to 0 1J Shale, Entoms -at top, - - - - 0 3J Tough shale, with fish-scales, teeth, and Catamite impressions, 0 4 Musselband, .... o 8£ Ironstone, - - - - up to 0 2£ Soft blaes, ..... ?

Section C, at ford, west of mill, left bank—a magnificent exposure— Feet. Inches. Thick sandstone, - Dark shaly blaes, 1 Tough cannel or oil-shale, 0 4 Black shale, 0 Musselband, 0 Ironstone, \ in. to 0 2| Musselband (local), 0 1 Soft fireclay blaes, 1 0

This horizon, being very constant over a wide area, forms a valuable index in mining; it separates the Kiltongue Coal and the Drumgray seams from the Virtuewell and thick upper coals of Lanarkshire.

3 Now a ruin; it lies at the bend just east of " stepping-stones." Downloaded from http://trngl.lyellcollection.org/ at University of Saskatchewan on March 14, 2015

282 TRANSACTIONS GEOLOGICAL SOCIETY OF GLASGOW.

The oil shale is a very tough, dull-looking rock, difficult to kindle, but burning with a bright flame. It resembles m appearance the well-known cannel coal of Torbanehill. The underlying musselband is a reddish-weathering band of shale crowded with shells of Carbonicola.

4. Ladygrange Goal to Kiltongue Musselband.—This part of the section is seen just east of the Caledonian Railway Pumping Station— Feet. Inches. Ladygrange Coal (parrot), (0 7J) Coaly fireclay, ----- 0 3 Fireclay, ... o 5 Blaes, ------5 6 Fakes and sandstone, 7 1 Blaes and ironstone ribs, 8 6 Fakes and blaes, - - - - 8 6 Dark blaes, ----- 1 1 Sandstone, - - - about 33 0 10 fins. 4 4£

5. Ladygrange Goal.—The probable representative of the Ladygrange seam shows the following section : — Feet. Inches. Oil shale with " mussels," Entomostraca, fish-teeth, and plant remains, - 0 4 Blaes, ------0 2 Fireclay and blaes, - 0 9 Coal (parrot), ----- 0 7* Coaly fireclay, ----- 0 3 Fireclay, - 0 5 The seam is local and variable throughout Lanarkshire. In the Garrion Burn area it varies from 4 inches to 7£ inches, and its distance above the K. Musselband may be 8J to 11 \ fathoms. The same seam at and Fauldhouse reaches 1 foot 7 inches, and lies 9\ to \\\ fathoms above the Musselband. In the Arden Basin4 it is 2 feet, and lies 8 fathoms above the Musselband. Westwards it seems to be very poor or absent; it occurs in the and Shettleston fields, but elsewhere near Glasgow is wanting. It is commonly underlain by a thin rib of ironstone.

4 See Geological Survey Memoir on sheet 31, page 36. Downloaded from http://trngl.lyellcollection.org/ at University of Saskatchewan on March 14, 2015

MACGRBGOR—THE GARRIONGILL SECTION AT OVERTOWN. 283

6. Virtuewell Goal to Lady grange Goal.—This section is a direct continuation of the last— Feet. Inches. Virtuewell Coal, - (3 114) Fireclay, - - 0 2 Sandstone and fakes, some blaes, 21 84 Blaes, ------2 6 Shaly blaes and ironstone ribs with " mussels " and Entomostraca, 0 88 Fireclay blaes, - 3 6 Sandstone, ----- 16 9 Blaes, with ironstone balls and ribs, - 3 0 Coaly blaes, - 0 1 Oil shale, with Carbonicola, Entoms., &c, 0 4 Fireclay and blaes, - 0 11 8fms. 1 74 7. Virtuewell Goal.—This seam is exposed on the left bank of burn just above mouth of tunnel at pumping station, and shows the following section :— Feet, inches. Shale, with fish teeth, &c, - - - 0 3 Hard coal, ----- 2 1 Softer coal, ----- 0 9 Hard coal, ----- 1 14 This coal is one of the most valuable seams in the Lanark­ shire field. It varies somewhat in thickness throughout the Wishaw-Law area; at Harestonhills it is 2 feet 9 inches, and has a 5-inch parrot coal on top; at Lanniesmuir it is 3 feet 1 inch, with an overlying 2 inches of parrot; at Garriongill Colliery it is 2 feet 9 inches, and on Wemysshill Farm it is only 1 foot 1 inch. Its distance above the Ladygrange varies between 8 and 9\ fathoms. At Shotts and Fauldhouse, where it goes under the name of Benhar Coal, it is 3 feet 6 inches and 4 feet respectively. 8. Splint Coal to Virtuewell Coal.—This part of the section is unfortunately obscured by the Caledonian Railway embankment. The following are the actual exposures seen in the burn :— Feet. Inches. Gap with old day level to Splint Coal, - ? Sandstone, - - - - 15 3 Coaly shale with " mussels," 0 74

6 An ironstone in approximately this position was worked in the Oreenhill and Cleland district, under the name of the Bellside Ironstone. See Geological Survey Memoir on sheet 31, page 34. Downloaded from http://trngl.lyellcollection.org/ at University of Saskatchewan on March 14, 2015

284 TRANSACTIONS GEOLOGICAL SOCIETY OP GLASGOW.

Feet. Inches. Blaes with ribs and balls of ironstone, 12 to 14 3 Sandstone, - 2 0 Blaes and sandstone ribs, 8 10 Dirty coal, .... 0 3 Coal, 0 3 Blaes and balls, .... 4 8 Kingly sandstone, 3 84 Blaes and ironstone ribs, 4 24 Coal, 0 3i Sandstone, .... 0 10 Blaes and balls, - 5 0 Broken rock of fault, - - 9 Coal with slaty rib, 1 4 Fireclay, .... 0 7 Blaes and balls with ribs of kingle, 7 Oh Gap, due to railway embankments, - ? Sandstone and fakes, - 10 4 Thin coal (not now visible), - ? Gap, probably with fault, - 9 r Shale, 0 3 1 Virtuewell Coal, - It is unfortunate that there are no bores from the Splint to the Virtuewell seams at any point close to the section. From bores in the surrounding country the following data are available :— The Virtuewell Coal is succeeded directly, or after a few feet of fakes, by a bed of blaes containing ribs of ironstone. The name given to this horizon is the Roughband Ironstone.6 It is not exposed in the Garrion. The next horizon of importance is a seam of coal lying between 9 and 11 fathoms above the Virtuewell. It is described as slaty, and may occur in two leaves, and is generally succeeded by several fathoms of fakes and sandstone. It is possibly represented by the 1 foot 4 inches coal of the above section. This seam appears to occupy the position of the Airdrie Blackband Ironstone, or the Blackband Coal which over most of the Lanarkshire field represents that horizon. Where of workable thickness, as at Viewpark, near , and at Starryshaw, near Fauldhouse, it furnishes an excellent house coal. Generally it is poorly developed. About 6 fathoms above the Blackband position occurs a

6 The Roughband of and Cleland lies also from 9 inches to 2 fathoms above the Virtuewell. Downloaded from http://trngl.lyellcollection.org/ at University of Saskatchewan on March 14, 2015

MACQREGOR THE GARRION GILL SECTION AT OVERTOWN. 285

9 inches to 1 foot 3 inches coal, succeeded generally by a great thickness of blaes and ironstone ribs, and a thick post of sandstone. It lies 10 fathoms below the Splint. This may possibly be represented in the Garrion by the higher of the two thin seams of the above section. Either this or the dark mussel shale, 3^ fathoms above, may represent the Musselband Coal of Rutherglen, &c. This, however, is a variable and impersistent seam, and cannot be identified with certainty in the Garrion area.

9. Splint Goal.—This seam is not now seen in natural section, but its position is fixed by old day levels. On Gillhead and Lawmuir its thickness was 6 feet. It is a hard, splinty seam, with ribs of dull cannel or parrot coal; the roof is a bed of blaes with ironstone balls, and the floor a thin fireclay. The Virgin Coal is not here a distinct seam. 10. Main Coal to Splint Coal.—This portion of the section is best seen between the day level to the Splint Coal, and the little bridge that crosses the Garrion about 500 yards S.W. of the pumping station.

Main Coal (see second section under Main Coal)— Feet, Inches. Blaes and Ironstone balls, 4 6 Fakes and sandstone, - 8 2 Blaes, - 1 9 Coal, .... 0 5 « Fireclay, 0 24 Fakes and sandstone, 20 10 Blaes and ironstone ribs, 1 3 Shale with Carbonicola, 0 11 . Blaes and ironstone ribs, 1 10i f Dark blaes, 0 10 Blaes and balls of ironstone, 8 6 Ironstone, up to 0 6 Blaes and ironstone ribs, 1 2 Coal, .... 0 2 Blaes and balls of ironstone, 8 24 < Sandstone and fakes, 9 4 Blaes, - . . 3 0 Sandstone, 5 2 Blaes, - 1 0 Sandstone, 5 0 Blaes with plants, - 3 or 4 0 ^Eye to Sj>lint Coal, -

14 fins. 2 9£ Downloaded from http://trngl.lyellcollection.org/ at University of Saskatchewan on March 14, 2015

286 TRANSACTIONS GEOLOGICAL SOCIETY OP GLASGOW.

The average distance between the Splint and Main Coals in this area is 14£ fathoms. The position of the Humph Coal of and Uddingston, which lies about 5 fathoms above the Splint, is probably represented by the 2 inches coaly layer of above section. Good sections of the same strata are seen on both sides of the burn, below the first crop of the Main Coal.

11. Main Goal.—This valuable and well-known seam can be seen at four points, viz.:— 1. Side of railway at Garriongill Junction. 2. Left bank of burn above little bridge, a continuation of Splint to Main section given above. 3. Left bank, S. of Garriongill Junction. 4. Day level, S. of little bridge. The following are the sections: — 1. 2. Ft. Ins. Ft. Ins. Blaes, - - - 0 6 Blaes, - - - 0 74 Hard coal, - - 2 8 Hard coal, - • 2 6| Dirty coal, - - 0 5| Soft coal, - - 0 5 Hard coal, - - 2 0 Hard coal, - -2 0 + Fireclay, - - 0 2 Fireclay, - - ?

Thickness of coal, - 5 \\ 4 114 + 3. 4. Ft. Ins. Ft. Ins. Blaes, ? Blaes, - - - 0 64 Dirty coal, - - 0 3 Coal, - - - 2 9 Coal, - - 1 8 Dirty band, - - 0 5 Coaly shale, - - 0 1 Coal, - - - 2 0 Fireclay, - - ?

Thickness of coal, - 1 11+ 5 2 Section 3 shows a local " wash-out" of the higher part of seam. The thickness at Castlehill Pit was 4 feet 7 inches; at Shaw- field Pit, 4 feet 11 inches; at Garriongill and Law Collieries, 4 feet 9 inches; there is a thin parting of soft, dirty coal towards the middle of the seam. 12. Ell Goal to Main Goal.—These strata are partially exposed in several sections. Of these, the best are— Downloaded from http://trngl.lyellcollection.org/ at University of Saskatchewan on March 14, 2015

MACGREGOR—THE GARRIONGILL SECTION AT OVERTOWN. 287

1. Right bank between little bridge and crop of Ell Coal. \2. Left bank do. do. do. do.

rS. Left bank above bridge at Castlehill orchard (S. of big fault). Feet. Inches. 9 o o 4. Left bank just S.W. of 20 fathom fault at Castlehill Pit. (Floor of Ell Coal) not seen, - /Fakes and blaes, 3 10 Fakes and sandstone, 4 1 Gap, - - ? 3 0 Sandstone and fakes, 4 0 Gap (some blaes and fakes seen), - ? 6 0 Blaes and ironstone ribs, 10 7

< CO Ironstone, - 0 6 Blaes and ironstone ribs, 3 04 Feet. Inches. Fakes and sandstone, 5 7 Blaes and ironstone ribs, 1 94 Dark shaly blaes with a few " mussels," Neuropteris, &c, 0 77 Blaes and ironstone ribs, 0 10 Coaly layer, - 0 14 Blaes and ironstone ribs, 5 3 Fakes, - 2 1 cS r-4 Q, Blaes and ironstone ribs, 0 44 Shale, .... 0 54 Coal, 0 11 Dirty coal, - 0 3 Blaes and ironstone balls, 3 0 J4 Fakes and sandstone, 2 9 i Reddened fakes, about 3 6 Burnt shale, - 0 6 -a White trap, .... 0 14 s Dirty soft coal, 0 3 Hard coal (burnt), - - 6£ to 0 74 \ Soft coal, .... - 2 toO 24 f Fakey blaes with ironstone balls, about 6 0 Sandy fakes, - 5 1 Thin bedded fakes with harder ribs, 4 0 \ Blaes, .... 0 6 ****** Coal, .... 0 Fireclay blaes, - 0 74 y (Main Coal), -

This band is known at Rutherglen and Cambuslang. Downloaded from http://trngl.lyellcollection.org/ at University of Saskatchewan on March 14, 2015

288 TRANSACTIONS GEOLOGICAL SOCIETY OP GLASGOW.

The distance between the Ell and Main Coals varies in this area from 10 to 15 fathoms, so that the above section is a fair average. It may be remarked here that the metals above the Main Coal position tend to vary somewhat from point to point. The Pyotshaw seam, for example, is irregular in thickness and in distance above the Main; it is thick enough to be worked by coal-cutting machines in Straven Colliery, about f of a mile east of the Garrion, and the floor at times comes dangerously near the old workings of the Main. A bore near Castlehill Pit gives its distance above the Main as 5 fathoms and its thickness as 1 foot 1 \ inches. In the Garrion Burn the 13-inch coal of the above section probably represents it. The 11-inch coal is well seen also at localities 3 and 4. The former of these shows a rich plant bed lying 2J fathoms above the coal. The following plants from this bed have been determined by Dr. Kidston : — Sphenopteris furcata. Sphenopteris latifolia. Mariopteris muricata. Annularia radiata. Neuropteris gigantea. Neuropteris heterophil la. Galamites undulatus. Asterophyllites equisetiformis. Sphenoph yllum cuneifolium. Lepidophloios acer'osus. Gordaites principalis. Some of the members of this assemblage indicate Middle Coal Measure affinities; Neuropteris heterophylla, on the other hand, is regarded by Dr. Kidston as characteristic of the Lower Coal Measure or Lanarkian Series.8 This part of the section is marked by the occurrence of thin sills of " white trap." These sills or " floats" occur at different levels in the Law and Shawfield coalfield. In the Brownlie workings the Kiltongue is locally overlain by an 8 to 12-inch sill, and in the Straven Colliery the roof of the Pyotshaw is also'of " whin." "A thin " white trap " occurs above the coal (probably the Pyotshaw) seen at the mouth of the 8 See Kidston—Proceedings Boy. Phy. Soc. Edin., 1893, vol. xii., p. 225. Downloaded from http://trngl.lyellcollection.org/ at University of Saskatchewan on March 14, 2015

MACGREGOR—THE GARRION GILL SECTION AT OVERTOWN. 289 first Main Coal day level on the right bank of the Garrion; another is seen in locality 3, 6£ fathoms above the Pyotshaw position; and another in locality 4, on a slightly lower horizon.

13. Ell Goal.—This coal is partially exposed on the left bank of the burn at bend just above the Gill Pit of Shawfield Colliery— Feet. Inches. Coal, 6 + Fireclay and blaes, 1 10 Fakes, - 8 0

It outcrops also on the side of railway about 300 yards west of Garriongill Junction, but the crop is now obscured. The section at Castlehill Pit was— Feet. Inches. Blaes, - - - - - 1 ft. 6 in. to 4 0 Coal, ------9 3j Fireclay, ----- 2 1

14. Upper Goal (?) to Ell Goal.—These strata are seen— 1. Immediately N. and S. of bridge at Castlehill Orchard. 2. At sharp bend 500 yards up stream from Castlehill Bridge. Section 1 is as follows: — Feet Inches. fCoal, - 1 54 Dirty coal, 0 3 Hard coal, 1 14 Dirty coal, 0 2 o Hard coal, 0 fil Fireclay, jH 0 9 Sandstone and fakes, - 23 »4 § 1 2 1 1 Pyritous coal, jl ft. lHins. - 0 7 Fireclay, 0 3£ 9' Pyritous coal . 0 5 [ Coaly clay, - 0 4 r-X -3 Fireclay, - 1 fathom 5 0 2*2 Gap, - 4 fathoms 3 11 ^Blaes and fakes (badly seen), say 12 „ 0 11 Left bank above bridge—Sandstone and fakes In section 2 this coal is 2 ft. 4 in., including a 4J in. fireolay. Downloaded from http://trngl.lyellcollection.org/ at University of Saskatchewan on March 14, 2015

290 TRANSACTIONS GEOLOGICAL SOCIETY OF GLASGOW.

The total thickness is about 24 fathoms; a rough estimate of section 2 gives the same metals as 25 fathoms, but neither section is complete, and the measurements are only approximate. A good average for the district is 26 fathoms. Further west the distance decreases; at Pather Farm it is 17§ fathoms; near about 16 fathoms; and at Rutherglen only 13 fathoms. To the south it decreases also. 15. Top of Section to Upper Goal— Feet. Inches. ^Sandstone and fakes, approx., - 30 0 Gap, very approx., 20 0 Sandstone, ..... 3 6 Gap (some fakes seen), approx., 15 0 Blaes, 2 0 I Fakes and sandstone, - - - - 19 10£ Blaes and ironstone balls, 6 4 Blaes and ironstone balls, some " mussels," - 3 7 { "Mussel"-ironstone, 0 2 8 n Blaes with "mussels," - - - - 1 3J Blaes with ironstone balls, - - - 1 6 Shale, 0 3J Coal, ...... 0 8 Blakes and fakes, .... 9 6 Shale with "mussels" and fish teeth, 0 3 to Coal, 0 8i 2 I Blaes and balls with sandstone ribs, - 17 9£ Gap, perhaps, ----- 12 0 fe CD (Blaes and ironstone balls, 5 4 Musselband ironstone, very limey, with Is " mussels," fish teeth, &c., - - 0 11 Ironstone, ..... 0 0J II Dirty coal, - - - - 2 in. to 0 3 <3J Fireclay, ..... 0 9 ^6 Blaes and Balls with 1 ft. 3 in. sandstone, - 6 6£ These are probably the highest beds met with. The 11 inches "Musselband" lying 7£ feet above the 3 feet 5J inches coal of this section is a very useful index horizon for this district. It has the same position relative to the thick upper seams of the Coal Measures that the Index Limestone has as regards the Limestone Coals. A similar band is met with near Station, at a distance of approximately 25 fathoms above the Ell Coal. It may represent the ironstone position at Palacecraig.