8. ]~Ie G~OT, OGICAL STRVCTW~ of the S Ow

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Vol. 55.-J . aE0r.0GICAT. STRUCTURE OF TWE SOUTHERN MALVERNSo 129

8. ]~ie G~OT,OGICAL STRVCTW~ of the Sow~,a~ ~[ALv~a~S, and of the AmAcE~r DIsTmc~ to the W~,sz. By Prof. T. T. GROOM, :M.A., D.Sc., F.G.S. (Read December 7th, 1898.)

[PLATES XIII-XV.]

CONTENTS. Page T. Historical Summary ...... 129 II. General Structure of the Area ...... 130 III. The ]Kalvern Range ...... ] 31 (1) Raggedst~)ne Hill. (2) 1Kidsummer and I-[ollybush Hills. (3) The Central Depressions in the Hills of the Southern Part of the Range. (4) The Hol]ybush Pass. (5) The Gullet Pass. (6) Chase End Hill (7) Confirmatory Evidence from the more Northerly Portions of the Range. (8) Theoretical Explanation of the Structure of the Southern Portion of the Malvern Range. IV. The Western Tract ...... 157" (1) The District of White-leaved Oak, etc. (2) The District around Fowler Farm. (3) The District around BronsiL V. The May Hill Sandstone Escarpment ...... 166

I~ ~'tISTORICAI, SUM]WARY. EASILY accessible, situated in a charmingly picturesque country, an~ marking some of the most interesting phases in the evolubion of the British Is]es, the Malvern Hills have now for nearly 80 years formed the subject of geological investigations, and have ever yielded new facts of interest and importance. Leonard Horner I described the Malverns as a granitic mass in- truded into the associated strata. Murehison 2 regarded the chain as essentially of igneous origin, though including ' Silurian' beds altered by the intrusion. Phillips, in his masterly work on the district, 3 maintained that the Lower Palmozoie strata associated with the range had been deposited against the crystalline rocks. I4o11, 4 regarding the range as probably composed of pre-Cambrian metamorphosed sedimentary and igneous rocks, described the Cam- brian aud Silurian beds as overlapping the metamorphic series. :Mr. Rutley 5 considers that the gneissic and schistose rocks of the Malverns are a series of altered tufts, grits, sandstmnes, and volcanic

'- Trans. Geol. See. set. 1, vol. i (1811) p. 281. 2 , The Silurian System,' 1839, pp. 417 etseqq. ; ' Siluria,' 1854, pp. 92et se~lq. 3 Mag. & Journ. of Sci. vol. xxi (1842) ; Mere. Geol. Surv. vol. ii (1848) pt. i, pp~ 66 et seq~. & pp. 125-126. Quart. Journ. Geol. Soc. vol. xxi (1865) pp. 89, 92, 97 et seqcb 5 l&id. vol. xliii (1887) p. 508. Q. J. G. S. iNo. 218. x .~176 N ,,

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::...: : ~ ,. .... , ,-- Faults '.::...:-).!:.:':!i:;"':'":"'"::::"~:~::"~=~":~~ V ~" .... tObscu,'e Faults ~ ~'~.-'~'X''~'''- ~'~" ," "~'~'" '~='z:~ '=' "'"' .... (and Boundaries. 300...... 326 z~ ~.-;~" ,~.,~'~'"~2 " ,~',Z~,","~r .-,~ ~.. ~ / .,"" GEOLOGICALlAP ~~/~ :" SOUTHEBN PART

Scalc: 4 i,~chcs lo lhc relic. ""'N"~'~ MALVERNS.

• Drift ~Trias [-~HaffieldBreoeia ~MayHill8aJ~dstonel I" ~J ( 'P~rmam ) I : : " : :'l and Conglomerate IBasalt &DiabaseV////Crey Shales ...... ~ Hollybush i .o//rb.sh Co,,oMo,,,. ~ Malvernia n "wuuu~ St,ilce of tJlaCK SRales ~ Sandstone erate and Quartzite { A ,chaean ) ~r~Juuuw~ Schiszs and Gno."ss ~ Breccia

[No~e.~One or the bands of basalt, occurring in the :Black Shales on the western side of" ~[dsmnmer ]=fill has been unintenti0nMly omitted here, but it is shown in fig. 1. Further, the small fault immediately to the left of tt in 'HOLLYBUStt,' and soufll of' the dip-arrow marked 55 ~ is incorrectly reproduced. Its southern termination should be about r inch more to the west : this wou]d show the northerly direction seen in the actual exposure.] Downloaded from http://jgslegacy.lyellcollection.org/ at Orta Dogu Teknik Universitesi on January 17, 2016

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130 PROF. T. T. OR00~ 0~ x~rR OZOLOOICAL [May 1899, and other igneous rocks. Dr. Callaway,1 on the other hand, regards the tbrmer series as metamorphosed plutonic rocks, chiefly granite and diorite, and compares them with the Archamn Series of Primrose Hill in Shropshire. The same author ~ recognized the volcanic series of the Herefordshire Beacon, and correlated it with the Urieonian rocks of Lilleshall Hill in Shropshire. The Herefordshire Beacon rocks have subsequently been studied by Green, ~ and by Messrs. Rutley, ~ Harker, 5 and Acland. 8 During the past year the present writer 7 has maintained that the Malvern and Abberley Hills are the basal wrecks of an old mountain-range which arose during Coal Measure times.

II. GE_~IERALSTRUCTURE 01~ THe. AREA.s The area which constitutes the subject of the present communication includes the southern end of the Malvern Range, as formed by Midsummer, Hollybush, Raggedstone, and Chase End Hills, together with the district~ of Coal Hill, Pendock's Grove, White- leaved Oak, Fowler Farm, and Bronsili, which lie immediately west of the range. This area is one of the most interesting in the Malvern district, because here the upheaval of the Palmozoie strata has been greater than elsewhere, and thus the Cambrian beds have been brought within the sphere of denudation 9whereas, along the rest of the range, the Silurian are the lowest Palmozoic rocks that come to the surface. The main axis of the joint mass of Midsummer and Hollybush Hills, like that of Swinyard Hill (from which it is separated by the Gullet Pass), runs about north and south ; that of Raggedstone Hill, which is bounded on the north by the Hollybush Pass, and on the south by the lower par~ of the ' Valley of White-leaved Oak,' runs :about north-west and south-east ; while Chase End Hill runs from north-east to south-west. On the east, these hills are bounded abruptly by the Trias, along an undulating line of fault. On the west, the lower parts of the slopes are formed almost exclusively by a flanking series of highly-inclined and much-dislocated Cambrian strata. At a short distance to the west of this southern part of the range is a half-lyre-shaped escarpment, well-marked for the greater part of its course, and formed by the May Hill conglomerates and sandstones. Between this escarpment and the Malvern Range is a partially- enclosed basin, or tract of generally lower ground, largely occupied 1 Quart~.ffourn. Geol. See. vol. xxxvi (1880), vol. xliii (1887), vol. xlv (1889), & vol. xlix (1893). 2 ]bid. vol. xxxvi (1880) pp. 536 et ,e~q. 3 Ibid. vol. li (1895) pp. 1-8. 4 /b/d. vol. xliv (1888) pp. 740 et seqq. 5 , Petrology for Students,' 1895, pp. 55, 143, etc. Quart. ffourn; Geol. Soe. vol. liv (1898)pp. 556~562. 7 :Rep. Brit. Assoc. 1898 (Bristol), p. 873. s Throughout this paper the signs M 100, 1~ 103, etc. refer to locMities corresponding to numbers in the map (P1. XIII), and to specimens collected at those localities. Downloaded from http://jgslegacy.lyellcollection.org/ at Orta Dogu Teknik Universitesi on January 17, 2016

Vol. 55-] STR~CTVl~,O~ ~av, sowmuU~ ~tALVEI~S. 131

by the Cambrian shales. For descriptive purposes this may be spoken of as the ' Western Tract.' Its surface is greatly diversified, owing to the presence of a number of intercalated bands and intrusive bosses of andesitic basalt and diabase, as well as by the inclusion of several faulted blocks of ~ay Kill Sandstone. These masses form a series of continuous or interrupted ridges or elevations, standing out more or less clearly from the surrounding lower ground. Some of the gentler elevations are capped or flanked by a stratified Drift of local origin. The district is, moreover, broken up by two small valleys, one running from the Kollybush Pass west- south-westward, and the other from the village of White-leaved Oak south-westward. The tract is partly under cultivation, and partly used as pasture- land; much of it towards the south, however, is occupied by woodland. The soil, in accordance with the varied petrographical ~haracter of the rocks, varies greatly in character, but is for the most part of rather poor quality.

III. TH~ MALVEm~"RAI~GI~. (1) Raggedstone Hill. (Figs. 1-7.) It is proposed to examine first the structure of l~aggedstone Kill, ]~ecausc it is here that the mutual relations of the various rock- masses are best shown. The hill is approximately triangular in outline, and is divided throughout its length by a curved depression running from north to south right across its centre, two distinct summits being thus formed, each of which attains a height of over 800 feet (see P1. XIV). North of the summits the depression broadens out north-north- eastward, and forms a hollow known as Winter Combe. On the south, too, the depression widens, as it curves south-eastward. This depression marks a line of dislocation, as already shown for part of its course by Hell, 1 and by ~[r. Rutley/ The former points out that the character of the rocks and the strike of the schists differ in the two halves of the hill. In Mr. Rutley's map this fault is represented as terminated by a transverse fault on the south ; but I shall in the sequel give evidence to show that it probably runs the whole length of the depression. That portion of Raggedstone Kill which lies east of the depression is formed by a mass of Arehamn rocks : this, according to the two authors named, is divided by faults into three main blocks. I think it. probable that a fault cuts off a fourth component block, forming that part of the eastern side of the hill nearest the large quarry on the Hollybush Pass. I have not attempted, however, fo represent these faults on the map (Yl. XIII), believing that the structure of the Arehman mass can be satisfactorily ascertained only after detailed mapping and petrographical study of the complex, 1 Quart. Journ. Geol. Soc. vol. xxi (1865) p. 75. ,2 Ibid. vol. xliii (1887) p. 488. ~2 Downloaded from http://jgslegacy.lyellcollection.org/ at Orta Dogu Teknik Universitesi on January 17, 2016

132 PROF. ~. T. ORO0~ 0~ ~E OEO~OGIOAT. [May I899 ,

such as is not attempted here. I have, therefore, contented myself with representing on the map (P1. XIII) the observed strikes and dips of the gneissic series. These dips, as indicated Fig. 1.--Diagrammatic Tlan of the strut- in the map, frequently ture of the north-western corner~fof show a marked relation t~aggedstone Hill, and of the south- to the direction of the western Tart of Midsummer Hill. axial fault~, the schists generally dipping away at a considerable angle towards the eastern side, and the strike conform- ing more or less closely to that of the curving fault. The exact position of the line of junction with the Trias is difficult to determine, as no exposures of the latter are seen close to the hill. It must, accordingly, be fixed chiefly by the character of the slope; for here, as elsewhere along the range, the steep slope formed by the Archman rocks gives place lower down to the much gentler slope of the Triassic area. The character of the soil occasionally af- fords assistance. The western half .of the hill is more complex in structure. The higher potions are formed, for the most part, of a strip of gneissie, schistose, and [S.cale : 6 inches : 1 mlle.] massive rocks, which may B.Sh. -- Black Shale. Q. -- Quartzite he traced from the road Hb.S. ---- Hollybush Sand- (black). stone (outcrops). Sch.-- Archman. in the Hollybush Pass to Hb.S'.--.Grey Hollybush FF. -- Faults. that in the 'Valley of Sandstone. White-leaved Oak.' The Hollybush Sandstone and Black Shales are- North of the contour- traversed by igneous rocks (fgn., cross-hatched). line of 800 feet the gneissie series is not exposed, and its presence is revealed only by d~bris and by excavations, but schists and gneisses appear to have been observed along the line by Holl2 The series can, however, be- Quart. Journ. Geol. Soc. vol. xxi (1865) p. 75. Downloaded from http://jgslegacy.lyellcollection.org/ at Orta Dogu Teknik Universitesi on January 17, 2016

~rol. 55.] srRucr~a~. OF ~K~ sourHs~ ~ALVF.RNS. 133 readily traced south-south-eastward from the summit of the hill, and may be Seen on the roadside near the bottom of the ' Valley of White-leaved Oak' (across which these rocks appear to pass) to terminate against the gneissic and schistose series of Chase End Hill. The Archman rocks are, accordingly, not completely cut out i, the manner snpp6sed by Phillips, ~ but are reduced to a narrow isthmus. At the top of the hill the strike of the series is generally from ~orth-east to south-west, but elsewhere it shows a clear relation to the boundaries of the strip, the prevailing dip being easterly, as on ~he eastern side of the hill (see map, P1. XIII).

The western slope and the north-western corner of Raggedstone Hill are formed almost exclusively by the Hollybush Sandstone, ~ogether with an associated series of igneous rocks. The junction ~)f the sandstone with the gneissic series can be determined with fair accuracy for a considerable part of its course. On the northern slope of the hill it is difficult to follow, since, unlike the majority of important junctions in the district, it is indicated by no depression, ~)r marked change in the angle of slope of the surface ; but south of the summit its position may be determined within narrow limits, although it is actually visible only in the large quarry near White- leaved Oak. The relations of the two series on Raggeds~one Hill have been regarded by Holl "~ and Symonds 3 as proving unconformable superposition of the sandstone upon the older series ; but careful examination indicates that the junction is a fault, both ia the northern and southern portions of the hill. The Hollybush Sandstone in the former locality appears to dip, on ~he whole, uniformly west-north-westward, at an angle varying from 40 ~ to 43 ~ ; the outcrops (see fig. 2, p. 134), plotted out according to the character of the slope, indicate that the beds abut against the gneissic series ; while the long dyke is abruptly cut off towards the south-east iu a way which is best explained by a fault. Here the sandstone shows a broken anticline, the summit of which forms a small sharp ridge running parallel to the junction. The axis of the anticline rises south-south-eastward. This fold was seen and figured by Murchison, 4 though he gave it a cone of crystalline rock, for the existence of which, however, I have seen no evidence. At the southern end of the quarry the fault is nearly vertical (see fig. 4, p. 136). On the east, a series of glossy sericite-schists dip on the whole east-north-eastward ; near the junction they are thrown into a series of small folds, pushed over towards the south-west, and with axes rising towards the south or south-south-east. The sandstone is separated from the schists by a few feet of brown, greyish-white, or green sandy limestone, dipping, like the adjacent sandstone, at a 1 Mere. Geol. Surv. vol. ii (1848) pt. i, p. 25. '~ Quart. Journ. Geol. Soc. vol. xxi (1865) pp. 89, 92, 97 et seqq. ' Records of the Rocks,' 1872, p. 34. ' Silurian System,' 1839, p. 418. Downloaded from http://jgslegacy.lyellcollection.org/ at Orta Dogu Teknik Universitesi on January 17, 2016

Fig. 2.--SIcetch-map of the neighbourhood of the large quarry at White-leaved Oak, showing the relatiorur of the Hollybush Sand- stone and the gneissic series.

Fig. 7. i F~ /~ Scale: 19~ inches=l mile, N

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•F [The shaded portion is theoretical ; the strike of the schists is represented by the strong rippled lines.] Downloaded from http://jgslegacy.lyellcollection.org/ at Orta Dogu Teknik Universitesi on January 17, 2016

Vo1. 55"] GEOLOG[CALSTRUCTURE OF THE SOUTHERN MA.LVERNS. 135

high angle south-westward. Farther away from the schists, at the top of the quarry, the flaggy beds bend over, so as to dip eastward. North of this point, and about halfway down the slope of the quarry, the sandstone and schists, together with their plane of junction, all dip wesb-south-westward at an angle of 25 ~ Still farther north-westward (fig. 6, p. 136) the sandstones at the top of the quarry dip west-south-westward. At an angle of 30 ~, but halfway down the slope, the beds suddenly turn over, and become nearly vertical. These are separated from the Archman rocks by a thin faulted block of impure brown limestone, followed by a few feet of the flaggy sandstone. The plane of junction of the latter with the schists dips west-north-westward at an angle of 30 ~. The schists are vertical, striking towards the west-north-west.

Fig. 3.--Section acros~ the junction of the sohists and Hollybush Sandstone, at a point south-south-east of the large ~uarry at White-leavec~ Oalc. s.w. // //17,,),,, F N.E. /'/".,"/.:.),',, ",i

Ho/lybosb- 8andstooe F ~iste [Scales : horizontal, 26 inches ---- 1 mile ; vertical, perhaps rather less.]

Combining the relations seen in these three sections (figs. 4-6, p. 136), the facts may, I think, be explained by supposing the existence of another anticlinal fold of sandstone, faulted against the Archmau massif, and against the more southerly-situated anticline, and overthrown towards the north-east, as indicated by the dotted lines in the sections. At the extreme northern end of the quarry (fig. 7, p. 136) the sandstone again dips west-south-westward at an average angle of 25~ while the schists dip irregularly, in a nearly opposite direction, at a very steep angle. About halfway between the points at which sections 6 & 7 were taken, more massive and darker beds of sandstone at the top of the quarry dip east-north-eastward at an angle of 60 ~. These beds are probably the same as those exposed in the two small quarries in the sketch-map (fig. 2), and are separated by one or more faults from Downloaded from http://jgslegacy.lyellcollection.org/ at Orta Dogu Teknik Universitesi on January 17, 2016

:Fig. 4.--Section across She south-western part of Raggedstone Hill. S.W. F F,) N.E. t a sF _ ~/-~uarry F

alack 8hale~ F Hollybush Sandstone, Schists with Limestone ( L)

:Fig. 5.--Section across the south-western part of Raggedstone Hill, a short distance north-west of that shown infig. 4.

::::::!-:", N.E.

Shales F Hollybush Sandstone

Fig. 6.--Sevtion across the south-western part of Ragged~tone Hill, rather to the north-west of that shown in fig. 5. S.W. F ""::"-::'-", F N. E, ) ..':.::.7:-----#',--Ouarry , ~~.:.::.-.-.--.~',...... :.-.--. !

Shales ~ [: F [Scale of figs. 4--6 : 38 inches = 1 mlle.]

Fig. 7.--~Seetion of the northern part of the large ~uarry at White-leaved OaIc. w.s.w. F) ,

Schists [Scale : 76 inches = 1 furlong.] Downloaded from http://jgslegacy.lyellcollection.org/ at Orta Dogu Teknik Universitesi on January 17, 2016

Vol. 55.] GEOrOSICALS~RCC~U~r 0r ~r~E S0U~HE~ ~ArVr.R~S. 137

the more thinly-bedded flaggy and shaly series seen in the sections hitherto described. Summarizing the relations of the schists and sandstones seen in the large quarry, it may be stated that the plane of junction is a fault, showing a close but variable relation, on the one hand, to the strike of the schists, and on the other to that of the sandstone. Prof. Lapworth informs me that the schists are of the nature of mylonites. The dips of the sandstone beyond the limits of the quarry are shown by arrows in the sketch-map (fig. 2; p. 134).

To the south the Hollybush Sandstone appears to be entirely cut ~)ut by faulting, and the Black Shales brought into direct contac~ with the gneissic series. Almost everywhere else along the line of fault the sandstone itself seems to be in direct contact with the gneissic series, but on the slope due west of the summit (see fig. 1, p. 132) ddbris of a quartzite and conglomerate may be found. In these I have obtained numerous specimens of Kutorgina cingulata and other fossils. This fossiliferous rock is not now exposed in place~ but Symonds 1 states that it was formerly quarried, and could be seen to dip at a high angle beneath the Kollybush Sandstone. At a point not far from the summit, and about 35 yards south of the outcrop of the diorite in the gneissic series, is a shattered quartzose rock, forming a rump near the end of a line of bushes and trees running up the slope. I have little doubt that this is the Hollybush Quartzite mod4fied in the vicinity of the fault, but no fossils were obtained from it. The general relations which have been indicated between the gneissic series and the flanking Cambrian deposits are, I think, incompatible with the idea, suggested by Hell, of an unconformity combined with rapid overlap, and can be adequately explained only by a fault. This is in harmony with the opinion expressed by Dr. Callaway,: though no evidence in favour of this view was adduced by him. The practically straight course of both the northern and southern parts of this fault, as they cross the contour-lines, suggests that the fault is on the whole nearly vertical, although, as seen in the large quarry to the south, it has by no means everywhere a plane surface.

The relations of the sandstones forming the north-western corner of Raggedstone Hill, to those constituting the narrow strip on the "south-western flank of the hill, are not clear. The dip in the former locality, as already indicated, is at a moderate angle towards the west,north-west, while in the latter case it is usually south-westerly or west-south-westerly, at a higher angle, and is occasionally reversed. Judging from the occurrence of quartzite at several points along a line running down the slope (fig. 1, p. 132) and from 1 , Old Stones,' 2nd el. (1881) p. 24. 2 Geol. Mug. 1879, p. 219. Downloaded from http://jgslegacy.lyellcollection.org/ at Orta Dogu Teknik Universitesi on January 17, 2016

138 VaOV. ~. T. aaoo~t oN ~r~, O~,OT.OOICAU [May i899 , the broken character of the more southerly strip, it is highly probable that a transverse fault separates the two series, and this view fits in better with the theoretical explanation of the structure of the hill given on p. 153. The pentagonal block forming the north-western corner of Raggedstone ]~ill is crossed by a thick dyke of andesitic basalt. This, being a durable rock, stands out, and forms the western face of a prominent rib running down from near the summit of the hill to cross the road in the Hollybush Pass. It is not an interbedded lava, as supposed by Hotl, 1 but is clearly intrusive, for it crosses the outcrop of the sandstone-beds in a marked manner, as shown in fig. 1 (p. 132). Where it is intersected by the road, it is seen to dip westward at an angle of about 30 ~. Along its western boundary, the Hollybush Sandstone is succeeded for most of the length of the hill by the Black Shales. The junction with these also is a fault ; for, although at one spot the tIollybush Sandstone has a reversed north-easterly dip, elsewhere along the line of junction the dip is south-westerly, while that of the Black Shales, wherever they are clearly exposed, is north-easterly.

(2) Midsummer and Hollybush Hills. (Figs. 8-10.) The portion of the range formed by these twin hills shows, in some respects, a structure similar to that of the Raggedstone. The joint mass is quadrangular in shape, and the two hills are separated on the south by a deep depression in which were formerly situated an old British town and what were apparently three old British reservoirs (P1. XV). The northern portion of the mass is divided into three parts by two depressions, one of which, running east- north-eastward, forms the northern boundary of Hollybush Hill; the other runs northward. The bulk of the two hills is composed of a mass of gneissic, schistose, and massive rocks, probably traversed by a number of faults, as indicated by sudden variations in the strike of the folia. On the whole, the mass exhibits a markedly plagioclinal structure, the foliation usually showing no relation to the boundaries, a feature in which these hills differ from Raggedstone and Chase End Hills. But in the large quarry at the southern end of Holly- bush Hill the schists dip east-south-eastward at a high angle. The Archtean Series is bounded on the east by the Trias, along a line of fault. The breccia marking this fault-line, and consisting of fragments of Arch~ean rocks and Triassic sandstone, is exposed in an old quarry on the roadside (M 191). 2 To the north a transverse fault brings the gneissic series against that of Swinyard Hill, with its flanking deposits of May Hill Sandstone. The lower part of the western slope of Midsummer Hill, for the greater portion of its l Quart. Journ. Geol. Soc. eel. xxi (1865) p. 87. 2 [Omitted unintentionally from the map, Ph XIII.] Downloaded from http://jgslegacy.lyellcollection.org/ at Orta Dogu Teknik Universitesi on January 17, 2016

u 55.] STRVCTU~EOF THE SOWHEV,N )~ALVV.WS. 139 length, is composed of Hollybush Sandstone, but the north-wes~rn corner of the hill consists of May Hill Sandstone. The H ollybush Sandstone is separated from the Archman Series by a northerly prolongation of the fault that runs down the north- western corner of Raggedstone Hill. This fault forms no feature in the landscape, and its apparently straight course across the contour- lines indicates that it is practically vertical. That the junction is really a fault follows from the dip of the sandstone behind the cottage on the northern side of the Hollybush Pass; the beds here strike directly towards the gneissic series. The Hollybush Quartzite, moreover, as on the western slope of Raggedstone Hill, appears to he absent along by far the greater part of the line of junction, but at one point a brecciated quartzite (M 173 a), 1 in places impregnated with heavyspar, is exposed. This has, so far, yielded no fossils, but its close lithological resemblance to the Hollybush Quartzite, as seen in hand-specimens and under the microscope, shows that it belongs to the Hollybush Series. At a distance of 1 or 2 feet from this rock the Hollybush Sandstone is exposed, apparently dipping at an angle of 20 ~ west-north-westward, and abutting against the quartzite, from which it must, accordingly, be separated by a fault. The May Hill Sandstone at the north-western corner of the hill was evidently noted by Phillips, who remarks that there are traces of ' Caradoe' Sandstone between the Obelisk and Midsummer Hill. 2 Ddbris from this patch are abundant, and furnished a variety of fossils, among which the following were recognized :--Striclclandinia Zens, Sow., Str. lirata, Sow., Pentamerus oblongus, Sow., P. g/o- bosus, Sow. (?), 'Petraia,' crinoid-stems, corals, etc. The beds are exposed in place, only at the extreme north- western corner of the patch, where the dip is 45 ~ eastward. These May Hill Beds are separated from the gneissie series by a well-marked band of hard conglomerate and quartzite, which I would propose to call the Hollybush Conglomerate and Quartzite. It can be traced from the bed of the stream flowing down the Gullet Pass, in a south-south-westerly direction, along the western slope of the ridge of gneissic rocks forming the northern extremity of Midsummer Hill. Its junction with this series is not marked by any depression or change of slope, but can be indistinctly seen in the road, where, though somewhat irregular, it dips on the whole east-south-eastward at 80~ the fault is, therefore, reversed. Both series can also be seen in the bed of the stream. The junction with the May Hill Sandstone is not exposed, but is indicated by a small depression, along which runs a footpath from the road. The conglomerate and quartzite are well seen in a small quarry (:M: 170)near the roadside, where the beds dip north by west at 32~ some of the layers here are crowded with fragments or whole shells of Kutorgina, etc. At a point farther south the dip ia apparently north 30 ~ west at about 15 ~ ; still farther south (M 366)

1 [, "]3 a' on the map, P1. XIII.] 2 Mem. Geol. Surv. vol. ii (1848) pt. i, p. 54. Downloaded from http://jgslegacy.lyellcollection.org/ at Orta Dogu Teknik Universitesi on January 17, 2016

140 PRof. ~. T. Gaoo~t O~ TrrE OrOLOeICAL [May 1899 , the dip appears to be easNsouth-easterly at from 60 ~ to 72 ~ while in the bed of the stream it is north-westerly at 25 ~. The strip is accordingly composed of beds which, in the south striking apparently parallel to the line of outcrop, in the north strike on the one hand against the gneissie series, and on the other against the May Hill Sandstone; it must, therefore, be bounded by two approximately parallel faults.

:Fig. 8.--Section across the northern slo2e of Midsummer Hill. W, Midsummer Hill E.

[Scale: 3 inches = 1 mile.] FF=Faults. [ c=Lower beds of May Hill Sand- e----Keuper Marls. ] stone, with Ctenodonta, ]_,i~- gula, etc. d--l?~ds of May Hill Sandstone, I b=Hollybush Quartzite and Con- with Stricklandinia. glomerate. a-- Archman. Towards the south the conglomerate cannot be traced as far as the northern limit of the Hollybush Sandstone; it is probably cut out by the meeting of the two faults which bound it. Moreover, a continuation of one of these faults probably truncates the Holly- bush Sandstone and the Black Shale which occur on the western side of :Midsummer Hill. To the north, both the gneissie series and the conglomerate are cut off by a transverse fault running east and west down the Gullet Pass.

Fig. 9.--Section of dyke on the northern side of Hollybush Pass.

Basalt Dyke Hollybush Sandstone [Approximate scale: 1 inch = I1 yards.]

The extent and disposition of the Hollybush Sandstone on the western slope of the hill are difficult to make out, as exposures are few, but careful examination makes it evident that the sandstone forms a somewhat narrow strip, bounded on the west by a fault which is approximately parallel to that on the eastern side of the strip. The position and direction of the fault can be determined by the junction along the middle of it, s length with the Black Shales on the west, and by the abrupt change in the strike and dip of the sandstone along the road from Hollybush to Upper House Farm. The fault is marked here by a slight depression running down a Downloaded from http://jgslegacy.lyellcollection.org/ at Orta Dogu Teknik Universitesi on January 17, 2016

Vol. 55-] STR~CTURV.Or Ta~. SOCTnER~ MALWZ~Z~S. 141

cottage-orchard. The dip behind the cottage is to the west of soutl~ at 75 ~ while immediately to the west the dip is west-south-westerly at 33 ~. It may be noted that the strike of the beds of the southern portion of the strip is almost straight across the length of the latter ; while close to the quartzite (M 173 a) the sandstone dips at 20 ~ west- north-westward, and strikes obliquely across the strip. In allproba- bility a transverse fault cuts off the southern portion of the strip. The south-western corner of Midsummer Hill is formed by a quadrangular patch of Hollybush Sandstone, invaded by a number of small intrusive masses of andesitic basalt. It stands out as a well- defined small hill, on the northern bank of the stream running down the Hollybush Pass. It is bounded on all sides by faults ; of these (four in number) that on the west, which separates it from a

Fig. lO.--Section across Midsummer ancZ Hoilybush Hills. Iffid- summer Hollybush Hill. Hill. F [ F2

:t ~ g~ e F c # a h~ a 'Fh [Scale : 4] inches ---- 1 mlle.] FF-----Faults. d----Black Shales (Cambrian). h-- Trias. c ----Hollybu sh Sandstone. ff-~ May ~ill Sandstone. b-----l~follybush Quartzite. f--Grey Shales (Cambrian). a=Archman. e--Igneous rooks in Black Shales.

faulted block of ~[ay ]:Jill Sandstone, is difficult to ~race. The dip of the Hollybush Sandstone in this varies from 33 ~ west-south- westward to 40 ~ west-north-westward, and thus approaches closely that noted on the other side of the Hollybush Pass. That intrusive mass of which the relations are seen most clearly, is well exposed in a small quarry on the road from Hollybusti t(~ Upper House Farm. The dyke is there observed to dip eastward, at an angle of 45 ~ (see fig. 9). The intrusive character of this dyke was recognized by Phillips.~ Four of the faults to which reference has been made enclose another quadrangular area (see-map, P1. XIII), the southern part of which at least, and, as I believe, the whole, is occupied by Black Shales, here, for the most part, baked grey by an associated series of andesitic basalts. The dip of these shales at the south-western corner of the patch is 25 ~ to west by south; while near th~ south-eastern corner it is about west 37 ~ north a~ 56 ~ One of the intrusive masses forms a well-marked, rounded boss, but th~ majority appear to be small sills. 1 ]~em. Geol. Surv. wl. ii (1848) pt. i, p. 53. Downloaded from http://jgslegacy.lyellcollection.org/ at Orta Dogu Teknik Universitesi on January 17, 2016

142 PROP. ~. T. O~O0~ O~ ~H~, ~EOT.O~ICAT. [May I899,

The general relations of the Arch~ean rocks of Raggedstone, ]=[ollybush, and Midsummer Hills to their flanking deposits, and the mutual relations of the latter one to another on the slope of the hills~ have now been considered; and it has been shown that these hills consist of a number of faulted blocks. Since the rocks of the formations concerned are everywhere separated by faults, it follows that no proof of the relative order of superposition of these formations can be given from the area considered. Nevertheless the axial position of the gneissic series, and the prevalent order of proximity of the remaining formations, clearly suggest the generally received order of superposition in the district. The conglomerate and quartzite are found only in contact with the gneissie series; the ]3lack Shales are generally more remote from the axis; while the Hollybush Sandstone occupies an intermediate position, and the superposition of the May Hill Sandstone on the shale series is fixed by evidence from other parts of the area described in these pages.

(3) The Central Depressions in the Hills of the Southern Part of the Range. (Figs. 11-15.) It was long ago observed by Phillips ~ that the Malvern range was on the whole a single chain of hills, but that certain hilL% such as Raggedstone Hill and the joint mass formed by Mid- summer and Hollybush Hills, showed two summits placed side by side. ]toll pointed out later 2 that in the case of Raggedstone Hill the eastern and western sides differed in structure and lithology, and he recognized the existence of a fault running down a part of the depression between the two halves. This deduction was confirmed by Mr. Rutley. 3 Apart from these, I am unaware of any observations bearing on longitudinal structural differentiation of the Archman axis. Now, the magnitude of the depressions which occur along the centre of Raggedstone Hill, and between Midsummer and Hollybush Hills, appeared to me too great to be explained by a simple fault. I therefore suspected the existence of softer or more easily denuded masses in the middle of the gneissie series, introduced, possibly, by earth-movements. A careful examination of the hollows showed that this conjecture was correct. The hollow on the southern side of Midsummer Hill (see t)1. XV) is bounded by two steep slopes, and has a somewhat sharply-defined, rather flat bottom, sloping down'towards the south-south-west. The gneissic rocks descend to the level of this floor. The floor itself is covered with turf, and no rock is exposed in place: but excavations made in former days, during the construction of the three old British reservoirs, and of the trench of the camp at the

1 Mere. Geol. Surv. vol. ii (1848) pt. i, pp. 9, 11, 26. 2 Quart. Journ. Geol. Soc: vol. xxi (1865) p. 74. 3 Ibid. vol. xliii (1887) p. 488, figs. 1 & 2. Downloaded from http://jgslegacy.lyellcollection.org/ at Orta Dogu Teknik Universitesi on January 17, 2016

Vol. 55.] S~R~C~CRS0~' T~E SOV~Tr~aN ~AT,W~CS. 143 top, resulted in the throwing out of some of the rocky bed of the floor. The ddbris from the middle reservoir consist chiefly, or solely, of fine-grained quartzite and conglomerate (M 169), which can be unmistakably recognized as belonging to the ttollybush Quartzite series. Immediately above the reservoir, fragments of purple Llandovery Sandstone and Grit were numerous (~[ 168): these ocmlrred as far up the hollow as the uppermost reservoir, where the fragments were most numerous (~ 167). Typical purple Llandovery Sandstone was also found close to the trench at the top of the hollow (~ 166). laieces of Llandovery Sandstone (~ 174), including a large block with Stridclandinia It- rata, Atrypa reticularis, Fig. 11.--Diagrammatie section, showing Pentamerus (?), Orthis, the junction of Archcean and Llandovery Leptcena (?), and Tentacu- strat a in the Hollybush Pass. lites anglieus, were found F at the top of the hollow W. ~• E .~.~• x " at the northern end of f/../,x x l=[ollybush Hill, and / I:l'•215 other fossiliferous frag- :" Xx 9J:IX X ments were obtained in ~/." '/ l I:l:I!,,x :1• ~ x the trench immediately I:I: ]• • x • above it. Phillips re- ~./ l:J" I• x • • marks 1 with reference .'. ~X X )r X x to this hill :--' It is 9 9 , Xx x somewhat singular to find pieces of fossilifer- /./.'/./.'/I~ x ~ x. I.'/'/.'/.I.| • • ~, ous Caradoc sandstones I'/.'l./.l'f, x amongst the loose masses 9 ." . . 9 |x x of the camp-mounds.' Now, there are no rocks on the higher parts . . ~ ",.Ix X X of the hill from which //////:,::: these fragments could i!i have been derived by . ~':/:/.'/.: x ~.X x gravitation, and it is hard to believe that their position can be due to an FF----Fault. j b = Green and yellow upward movement of ice e--Decomposed put- ] sandy shales. from lower levels, more ple sandy rock. ] with traces of particularly as there is, d =Yellow sandstone; 1 crinoids ; 18 so far as I know, no proof 4 inches thick, t inches thick. c----Blue clay; 10 ]a=Arehman (die- of the existence of glacial inches thick. I rite). conditions over the Mal- vern Range. The 0nly possible explanation is, I think, that slips of the :gollybush Conglomerate and May :gill Sandstone occur beneath the turf and ddbris ; and that the hollow, in part at any rate, owes its existence to the excavation of the easily-denuded materials of these formation#(see fig. 10, p. 141). 1 Mem. Geol. Surv. vol. ii (1848) pt. i, p. 28. Downloaded from http://jgslegacy.lyellcollection.org/ at Orta Dogu Teknik Universitesi on January 17, 2016

~ w~'~._g~ ~' 84

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Vol. 55.] OS0LOOlCAn STRUCTURE OF THE SOUTHERN MALVERN$. 145 This conclusion was confirmed by the discovery, made later, of a patch of May ]:Jill Sandstone in place, embedded ill the heart of the Malvernian gneissic series, at the extreme southern end of the hill, and along what is evidently the same line of dislocation. Along the northern side of the road in the I-Iollybush Pass, exactly opposite the 4th milestone from Ledbury, may be seen the junction of this strip with the gneissic series. The May Hill Beds of the patch apparently consist chiefly of a purple grit, which is exposed only in a weathered condition, but may be reached by excavation. The width of the zone along the road is perhaps as much as 50 yards. A little more than this distance west of the milestone, rocks of the gneissic series were again reached by excavation. Fig. 11 (p. 143)represents the relations seen opposite the milestone. The dip of the sandstones is predominantly west- north-westward at 60 ~ The junction is clearly a fault, with an undulatory surface, which runsabout north and south, and, for the most part, dips eastward at an angle of about 80% The evidence from the hollow on the southern side of Ragged- stone Hill is of a similar nature, but less obtrusive, fragments other than those of the gneissic series being rare. Immediately above the road I found a large block of ttollybush Conglomerate (~[ 177), and at the level of the north-western margin of the two small copses in the hollow (~ 178) another piece of tIollybush Con- glomerate, together with large fragments of purple Llandovery grit, were obtained. At an intermediate point fragments of Hollybush Sandstone were found; these, however, possibly came from the ridge bounding the western side of the hollow a little higher up, the crest of which is formed by the sandstone, but no such origin can be assigned to the other two kinds of rock. In the upper part of the hollow no fragments can be found, except d6bris from the "Arch~ean rocks of the slopes, and in all likelihood no Palaeozoic rocks are present at this point, the strips which occur lower down having probably a lenticular shape. An important feature of this hollow is the practical certainty that a line of dislocation runs down it, as first shown by ttoll. 1 In the large hollow on the northern side of Raggedstone tIill, known as Winter Combe (see P1. XV), the proofs of the inclusion of Paleeozoic rocks in the Archman Series are more satisfactory. Along the western slope of the hollow there is a distinct outcrop, for some distance, of Hollybush Conglomerate (M 164), which dips between west and west by north at 40~ that is, straight towards the gneissic series, from which it is, accordingly, in all probability, separated by a fault. This band of conglomerate forms a low rounded ridge. Fig. 14 (p. 146) represents a section drawn across it to scale, with a length down the slope measured in yards. The Arch~ean rocks are not exposed at this point, and the position assigned to them is inferred from the mapping. Immediately north x Quart. Journ. Geol. Soc. vol. xxi (1865) p. 74. Q.J.G.S. No. 218. L Downloaded from http://jgslegacy.lyellcollection.org/ at Orta Dogu Teknik Universitesi on January 17, 2016

146 vRov. ~. T. G~OOM O~" ~H~. OEOLOGZCA~ [May I899,

of the chief exposure of conglomerate an apparent continuation of the ridge, to which allusion has been made, is formed by a small block of Archman rock, reached by excavations. This appears to join the main zone of the gneissie series which runs down the northern slope of the western side of l~aggedstone Hill, for excavations made to the north of the observed outcrop of the conglomerate indicate that the latter is absent, presumably by faulting out. In conse- quence of the lack of exposures along the line of contact of the conglomerate and this sm~ll block, I am unable to say whether the case is one of superposition of the conglomerate on the gneissic series, or whether the junction is merely a fault. An oblique fault running north by west would explain the phenomena observed.

Fig. 14.--Section in Winter Combe (north side of Raggedstone Hill). F E. (a b is about 52 yards in length.) i W.

Ix • x• b !• x x • '~xX Xx x x x x x x x x x x x x i?xXx ,x x x • • Ix x x x

iiIxXX x x_ ePalo x x x j x ]x x x x F Archman

:East of the conglomerate and gneissic rocks, and forming considerable portions of the bottom and of the eastern and western slopes of the hollow, is a great mass of Hollybush Sandstone. This, it is true, is nowhere exposed in place, but its existence is proved by the very considerable stretches of wood covered with ddbris of nothing but the sandstone. The ddbris extend up to a height of over 700 feet on the western side of the wood, and in the lower part of the wood the sandstone-area covers a considerable breadth. The western boundary of the mass is indicated by a slight depression just within the wood; this probably marks a faulted line of junction with the conglomerate, for otherwise the conglomerate would appear to overlie the sandstone, which there is every reason to doubt. This junction appears to continue the curving line of dislocation which traverses Raggedstone Hill, for Archman rock occurs not only in the little ridge to which reference has been made, but also in place on the southern side of the road, immediately opposite the entrance to the large quarry. It was reached, I am informed by Mr. Summers, in laying the foundation of the Mission Chapel, and in excavations made in the gardens for some little distance to the cast. It is probable, accordingly, that the ttollybush Sandstone extends down Downloaded from http://jgslegacy.lyellcollection.org/ at Orta Dogu Teknik Universitesi on January 17, 2016

Vol. 55"] STRUCTUREor TeE S0UTH~RN ~tALV~R~S. 14 7 to about the level of the road, where it must be cut out by the meeting of the two faults which bound it: but it does not pass beyond the road, for north of this Archsean rocks are everywhere present. Winter Combe is, then, a hollow excavated in a shattered complex of more or less lenticular masses of ttollybush Sandstone, Hollybush Conglomerate, and rocks of the gneissie series.

Fig. 15.--8ection across the northern ~art of 2~aggedstone Hill.

[Scale : 4~ inches = 1 mile.] FF--Faults. d--Dyke in Itollybush Sandstone. g=Trias, c=Hotlybush Sandstone. f= May Hill Sandstone. b= ttollybush Conglomerate. e: Grey Shales (Cambrian). a:Arehsean. Comparing the foregoing observations, attention may be drawn to the fact that the included patches of Palseozoic rock all occur along a cont.inuous line of depression which, starting at the south- eastern end of t~aggedstone Hill, runs first in a north-westerly, and then successively in a north-north-westerly, northerly, north-north- easterly, and north-easterly direction, finally turning eastward. Its course is practically a semi-ellipse. This hollow marks a complex line of powerful disturbance, along which differential movements, to the extent of 2000 feet or more, have taken place.

(4) The Hollybush Pass. This district has already been described in speaking of the adjacent slopes of the hills on each side, and one point alcne remains for consideration. The existence of a deep transverse depression extending right across the range is remarkable, but the student of the Malvern district soon learns that many of the faults of the area are marked bv lines of depression at the surface. Hell, indeed, long ago ~ expressed his belief that some of the passes between the hills have been determined by lines of fault. It is not easy to prove the existence of an important fault running the whole length of the Pass, but there areseveral distinct pieces of evidence which point to this conclusion. On the west, the boundaries of the Hollybush Sandstone appear to be continuous across the Pass, and the general dip of the beds is similar in both direction and amount; but the bohaviour O f 1 Quart. Journ. Geol. Soc. vol. xxi (1865)p. 95. : L2 Downloaded from http://jgslegacy.lyellcollection.org/ at Orta Dogu Teknik Universitesi on January 17, 2016

148 PROF. T. T. OROOM ON THE OEOLOGIOAL [May 1899,

the intrusive masses is besb explained by a fault. The two main dykes running down the adjacent slopes are not continuous across the depression, as was apparently supposed by Phillips, 1 for mapping shows that neither passes beyond the bed of the stream. The very different dip and strike of the two necessitates the conclusion that the dykes do not even meet one another, and that in fact the ends of two different dykes are brought into proximity along a transverse line of faulting. The same fault wolfld appear to form the southern boundary of the strip of sandstone east of that which contains the igneous rocks at the south-western corner of Midsummer Hill, for the dip of the sandstone here is different from that on the southern side of the stream. A continuation of the same line of faulting towards the west-south-west would coincide with the northern boundary of the patch of May Hill rocks near Fowlet Farm, to which ~llusion will be made later, and also with that of the Black Shales on the west of this patch. It is diit%ult to say whether the great axial line of dislocation has been displaced by this fault or not ; but, judging by the probable distribution of the rocks concerned, as indicated by the relief of the surface, a certain amount of displacement has occurred. I could detect no traces of the May Hill Beds on the northern slope of Raggedstone Hill: the position that they might be expected to occupy, were there no transverse faults, would, indeed, seem to be taken up on the southern side of the Pass by a small mass of Arch~ean rocks. The fault is probably one along which varied differential movements of the blocks concerned have taken place, for no simple movement would appear Go be capable of bringing about the observed relations of the rock-masses.

(5) The Gullet Pass. The Gullet, or line of depression between Midsummer and Swin- yard Hills, as already pointed out (p. 140), is a line of dislocation. Against this fault end the four faults bounding the Arehman blocks on the north and south. It is in part, at any rate, of post-Triassic age, for it has dislocated the great fault by which the Triassic rocks have been thrown down on the eastern side of the range (see map, P1. XII[).

(6) Chase End Hill. (Fig. 16.) The structure of this southernmost portion of the Malvern range is simpler than that of the hills already considered. The hill is somewhat lanceolate in plan, and its axis meets that of the southern par~ of Raggedstone Hill at about a right-angle. The greater part of Chase :End Hill is formed by an elongated elliptical mass of schistose and gneissic rocks. Near the north- i Mere. Geol. 8urv. vol. ii (1848) pt. i, p. 53. Downloaded from http://jgslegacy.lyellcollection.org/ at Orta Dogu Teknik Universitesi on January 17, 2016

u 55.] SvI~VCVVRS07 ~ S0WI~m~N ~tAT.VP,RNS. 149 eastern end of this mass the hill sends a spur towards the north- west. This is represented in the Survey maps as a continuation of the gneissie series, but in Holl's map' it is correctly marked as part of the Malvern Shale Series. A smaller, more northerly spur runs north-westward t~om the extreme northern end of the hill. This is formed by a slip of :Hollybush Sandstone, together with Black Shale and basalt. The structure of these spurs may be conveniently considered together with that of the district of White-leaved Oak (p. 159). The schistose and gneissic rocks of the hill appear to be bounded everywhere by faults: on the south-east and east, by the great fault which brings down the Trias; on the north-west, by a fault which intersects the surface in a curved line, against which strike the successive zones of the Malvern Shales.

Fig. 16.--Section across Chase End Hill, on the scale of 6 inches to the mile. F...... ( "-.. F: W.bys. ~ --. \ ~.bys. ~176

""-F ~F' [The above figure represents the probable relations bf- the rocks of the hill ; the section is not drawn parallel to the dip of the shales; nor to that of the fault, and thus both dips appear to be lower than they really are.] F'F'=Fault between Trias and b=Grey Shales, with interbedded Arohman. diabase (Coal Hill igneous FF= Fault. band). d = Trias. a = Arehtean. c=Upper Grey Shales.

The Triassic rocks are exposed along the drive to Bromsberrow Place, in the form of a red sandstone with occasional pebbles of pink quartz. The dip is south-westerly at about 20 ~. The fault running along the north-western slope of the hill curves round on the north-east towards the east, and on the south- west towards the south-east, as it descends to lower ground in each case. The actual junction is nowhere exposed, but a plane fault dipping south-eastward at an angle of 30 ~ would give an outcrop closely agreeing with that observed (fig. 16). The Upper Grey Shales, wherever seen close to the ridge, have a reversed dip towards the east-north-east, while the lower strata of the same series, with interbanded basalts, seen in the spur farther north-eastward, dip east by north.

1 Quart. ffourn. Geol. Soc. vol. xxi (1865) facing p. 72. Downloaded from http://jgslegacy.lyellcollection.org/ at Orta Dogu Teknik Universitesi on January 17, 2016

150 trot,. T. ~. GROOM OX TrtE Gr:OLO~ICAL [May I899,

(7) Confirmatory Evidence from the more Northerly Portions of the Range. (Fig. 17.) The boundaries of the Arch~ean complex in the central and northern portions of the range have been careflllly mapped, and the conclusion has been reached that, as in the south, the western boundary is always a fault, sometimes vertical, and sometimes reversed. A description of these portions of the range is reserved for a future communication, but in view of the scarcity of exposures of the junction with the Palmozoic Series in the south, I have thought it well to give an example from the middle portion of the range, which proves that, on the one hand, the Archman Series has been intensely folded, and that, on the other, it has undergone powerful overthrust on to the Silurian rocks.

Fig. 17.--Section of the ra',ge (dong the line of the Malvern Tunnel. F',,e,,

r e ,a b'-, a "8 i 9"F %% -F ~ F,,

[Scale : 46 inches = 1 mile.] rr=Railway-level, l e = Wenloek Shale. F'F'=Fault between Trias I d = Woolhope Limestone. and Aroht~an. [ c = Tarannon Shales. FF=Faults. I b = May Hill Sandstone. = Breccia. I a=Areh~can. Trias.

The above figure represents a section drawn ix) scale across the range, along the line of the Malvern Tunnel. The succession of strata in the tunnel is taken from Symonds & Lambert's description, 1 in which measurements are given. The junction of the Archman with the May Hill and Triassic strata on the slope of the hill has been fixed by careful mapping. It is clear from this section that the fault separating the Arch~ean rocks from the May ]:fill Series has a very considerable hado towards the eastern side of the hill. The angle of apparent dip indicated by the line joining the point of outcrop at the surface with that of intersection by the railway is about 57 ~. Making allowance for the angle at which the railway cuts the dip of the plane of junction, as deduced from its outcrop, I estimate the true dip as being about 65 ~ east, 7 ~ south. That the junction really dips eastward was noted by Symonds & Lambert, 2 who state that the

t Quart. Journ. Geol. See. vol. xvii (1861) p. 152. 2 1bid. pp. 155, 157. Downloaded from http://jgslegacy.lyellcollection.org/ at Orta Dogu Teknik Universitesi on January 17, 2016

Vol. 55.J STRUCTUREOF VaE SOU~EaN ~ALWRSS. 15t vertical Llandovery Beds, which show indications of great pressure and crushing, rest against the overhanging ' syenite.' An important feature in this section is the occurrence of a' vein' of Llandovery rock included in the ' syenite,' and consisting of two thiu bands of limestone (each ?) about 6 inches thick, with aa intervening bed of' marl,' 2 feet thick. These beds, according to Symonds, furnished Stricklandinia. 1 It is unfortunately very difficult to make out the disposition of this ' vein' from Symonds & Lambert's description, 2 but on comparing the figure and the context it seems to follow that it has a low easterly dip. The same or another strip of beds containing Stricklandinia was also described by Phillips ~ as occurring in the crystalline rock of the Wyche Pass, a short distance north of the line of the tunnel. Symonds explains these facts by supposing that the fossiliferous rocks were dropped into an open fissure traversing the crystalline floor of the Llandovery seas ; but, now that the great effects accom- panying the process of mountain-building are known, no one will, I think, seriously maintaiu this view, and I would apply the same explanation here as in the case of the included Cambrian and Silurian strips in the southern part of the ]~alvern chain, namely, that of profound infolding, combined with faulting.

(8) Theoretical Explanation of the Structure of the Southern Portion of the Malvern Range. (Figs. 18-20.) The broken and dislocated condition of the gneissic complex of the Malvern Hills was realized many years ago by Phillips, who in this connexion drew special attention to the occurrence of crush-breccias. These breccias have been noted subsequently by HoU, Rutley, and Hughes, the latter of whom has given an explanation of their origin. 4 The two former have also indicated the occurrence of faults traversing the gn~issic series. Now, the faults occurring in the range are by no means always of the simple character of those to which allusion has just been made. It has been shown above (p. 137) that )~idsummer and Raggedstone Hills are traversed by a complex line of dislocation, along which strips of Cambrian and Silurian rocks, presumably often of lenticular shape, have become included in the Archman Series. The inclusion of these narrow strips is difficult, and [ think impossible, to explain oa the hypothesis that they are portions of an overlying series let into the gneissic series by ordinary faulting. At the only spot (fig. 11, p. 143) where the actual junction of the included rocks with the Arch~ean Series is exposed, the fault is seen to be a reversed one, but with a relatively small hade. The circumstance, moreover, that the outcrop of the line of disturbance curves round towards the east, as it descends both the northern and southern slopes of 1 , Old Stones' 2nd ed. (1884) p. 47. 2 Quart. Journ. Geol. Soc. vol. xvii (1861) p. 157. 3 Mere. Geol. Surv. vol. ii (1848) pt. i, p. 64. 4 Geol. Mat. 1887, p. 500. Downloaded from http://jgslegacy.lyellcollection.org/ at Orta Dogu Teknik Universitesi on January 17, 2016

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~ ll II Downloaded from http://jgslegacy.lyellcollection.org/ at Orta Dogu Teknik Universitesi on January 17, 2016

u 55.] O~,OTOOICALSTRUCTURE OF THE SOUTHERN ~ALVERNS. 153

Raggedstone Hill, suggests that it has on the whole a distinct easterly dip, and therefbre passes underneath the gneissic rocks of the eastern side of the hill. Further, it will be shown on a future occasion that, in the more northerly portion of the range, the eastern fault bounding similar included Silurian strips is either vertical, or has a very marked hade towards the east. There is, then, evidence to show that the gneissic rocks on the eastern side have been thrust up vertically, or at an anglo, over the more westerly Cambrian and Silurian rocks. This hypothesis necessitates, further, the presence of folds sufficiently deep ~o bring the Palmozoic strata down to the level at which they are found. I have endeavoured to represent this view in the entirely diagrammatic figure facing this page. ~e must suppose that a deep fold of Cambrian and Silurian rocks, including on the one hand the Hollybush Conglomerate, and on the other beds of the May Hill Series, became included in the gneissie complex, the middle limbs being drawn out by the great tension into a series of shreds, or in places entirely obliterated. A fact worthy of note in this connexion is that, though the ]=[ollybush Conglomerate and Sandstone, and the May Hill Sand- stone are represented in this squeezed and dislocated zone, the Malvern Shales, the position of which is intermediate between the two last-mentioned formations, appear to be entirely unrepresented. There is, as I shall endeavour to show later, reason to believe that these beds, like the other Cambrian and the Silurian strata, formerly passed over the range, and I would suggest that during the intense folding and crushing which took place these softer beds were completely squeezed out, in the manner indicated in fig. 18. t The enormous crushing which some of the beds have undergone is shown by the greatly shattered and breceiated condition of the pieces of Hollybush Conglomerate found in the hollows at the southern ends of Midsummer and Raggedstono Hills respectively. Very significant in connexion with these folds arid thrust-planes are the definite relations which obtain, between the strike and dip of the schists of Raggedstone Hill and the course of the axial dislocation as shown in the map (P1. XIII). The schists nearly everywhere on the eastern side of the hill dip away from the line, their strike curving round with a fair amount of regularity; the schistose rocks on the western side of the hill show a similar but less marked relation, the folia dipping towards the axial line in this case. It can hardly be doubted that the production of the schistosity and that of the zone of dislocation are closely related. Further evidence tending in the same direction is seen in the western slopes of Raggedstone Hill. it has already been pointed out (p. 137) that there is commonly a distinct relation betwben the dip and strike of the Cambrian rocks and of the schists, on the one hand, and that of the fault-plane separating them on qthe

i I do not, however, feel perfectly satisfied with this explanation, for some traces of the igneous rocks abundant in parts of the shale series might tm eapected to occur. Future research may remove this difficulty. Downloaded from http://jgslegacy.lyellcollection.org/ at Orta Dogu Teknik Universitesi on January 17, 2016

154 PROF. T. T. GROOk[ ON THE GEOLOGICAL [~[ay i899, other. The schists commonly dip towards the axis of the hill, as also do the inverted Black Shales, and sometimes the ttollybush Sandstone. The schists in the large quarry at White-leaved Oak show clearly a series of small folds overthrown to the west, and it may be seen that they are traversed by a small reversed fault. Taking into consideration this disposition of the schists, together with the inversion of the Black Shales, I would suggest that evidence here exists of au overfold towards the west, the Arch~ean strata having been thrust over the Cambrian Series, with the result that

Fig. 19.--Diagrammatic view of the structure of Micls'~tmmer ttill.

FF= Faults. d-- Blaek and Grey Shales (Cambrian). F'F'=:Fault between Trias and c-~ Hollybash Sandstone. Areh~ean. b=Hollybush Quartzite and Con- g----Trias. glomerato. f-- Haflleld Breccia. a = Arch~ean. e=May Hill Beds. xx-~ Present surface. new planes of schistosity were introduced in the former. The fold was finally ruptured by a fault, which probably was nearly vertical. The disposition and relations of the Hollybush Sandstone, however, need further elucidation. This, as already shown, is probably thrown into a small overfold, the axis of which dips towards the west, as also does in some cases the fault-plane between it and the schists. Figs. 4, 5, 6, & 7 (p. 136) illustrate this arrangement. I Downloaded from http://jgslegacy.lyellcollection.org/ at Orta Dogu Teknik Universitesi on January 17, 2016

Vol. 55.] STRUC'rUR~ OF THE SOUTaER.'q X[ALVEP~N$. 155 would suggest that originally the schists and sandstone and the fault separating them dipped eastward, but that movements, a little later than those which produced this thrust, resulted in the formation of a small overfold towards the east.

The structure of Midsummer ]=Jill and of the north-western corner of Raggedstone Kill presents points of difference from that seen in the greater part of the last-named hill. Ther~ is au axial thrust-plane, the gneissio and schistose beds above which, at the southern end of Hollybush Hill, dip eastward. D6bris of iossiliferous May Hill Sandstone found in the trench at the extreme northern end of the camp, at a height of about 750 feet, may ~ possibly indicate another thrust-plane: but the foliation of the schists and gneisses in general does not appear to show any relation: to the axial thrust-plane, nor to the boundaries of the gneissie complex. Th~ hill, indeed, shows in a marked way tile structure termed plagioclinal by Dr. Callaway. The dipof the Cambrian beds, moreover, is prevailingly towards the west, no signs of inversion being seen, except in the case of the conglomerate near the northern end of Midsummer Hill (M 366). The structure may be explained in much the same way as that of the greater part of Raggedstone Hill, if we supoose the movement not to have been generally great enough on the one hand to produce overfolding on the western side, or, on the other, to induce new planes of foliation on a large scale (see fig. 19). Secondary foliation appears, however, to have taken place at the southern end of Hollybush Hill above the axial thrust-plane. The plagioclinal structure seen in Midsummer Hill and in many other parts of the Malvern range is perhaps best explained by the hypotheses of Dr. Callaway, 1 who suggests that the Cambrian beds rest unconformably upon the Archman. The latter series had in pre-Cambrian times undergone an extensive process of folding beibre being denuded, the axes of the folds crossing the direction of the range obliquely. Little need be said about the structure of Chase End Kill. If the explanation given on p. 149 bc true, this hill constitutes a case of extensive overthrust, the overridden shales being inverted by the movement, and a new foliation having been probably developed in the Archman rocks. That such extensive overthrust has occurred in parts of the Malvern range the evidence given on p. 150 is sufficient to show : there is proof of intense folding, accompanied by the formation of thrust-planes. Fig. 20 (p. 156)is an attempt to explain the structure of the western part of the range at the point at which the section in fig. 17 (p. 159) is drawn. To summarize, I would susgest that the Southern Malverns are a portion of~ an intensely folded and faulted complex of Arehman, Cambrian, and Silurian rocks, showing the characteristic features of a folded mountain-range, with its overfolds and thrust-plan6s.,

1 Geol. Mug. 1879, pp. 219-221. Downloaded from http://jgslegacy.lyellcollection.org/ at Orta Dogu Teknik Universitesi on January 17, 2016

156 raoF. z. T. Gr,OOM ON Tar av,OrO~ICAL [May 1899,

One interesting point of resemblance to certain typical mountain- ranges is the occurrence of transverse faults, such as that which runs down the Gullet Pass, between Midsummer and SwJnyard Hills. It follows, moreover, from Phillips's description of the Silurian rocks west of the Malverns, 1 that the strata are thrown into a series of normal folds, which run in a direction generally parallel to that of the Malverns themselves ; the anticlines of this system have a steep westerly, and a more gentle easterly dip, so that the axes dip eastward. This series of folds Fig. 20.--Theoretical restoration of the (fig. 18, p. 152)is a good section of the ~Ialvern Hills along the example of the Aust6- line of the Malvern Tunnel (p. 150). nungszone commonly associated with mountain-ranges. A further apparent resemblance to such ranges consists in the depressed block of ', ',1/~ country east of the Mal- verns : this, at first sight, may be held to constitute the Abgesunkenes Riickland of Conti- nental geologists; but it must be noted that the movement which took place along the line of fault between the Mal- vern range and the Trias of the Vale of Gloucester is, in part at any rate, necessarily of post-Tri- ass~c age, and hence long subsequent to the movements which produced the old Malvern range. Beneath the' Permian' and Triassic rocks east of the hills, there is every reason to believe that relics of tbe easterly ex- N .F tension of the old range survive. Such formations xx=Present surface, b=Lower Palaeozoic. have long been known to FF= Faults. ,a = Arch~ean. rest; directly upon the older series in the Malvern and Abberley districts. The fault on the eastern side of the Malvern range has depressed the Archman

i Mere. Geol. Surv. vol. ii (1848)pt. i, p. 134. Downloaded from http://jgslegacy.lyellcollection.org/ at Orta Dogu Teknik Universitesi on January 17, 2016

u 55.] STRUCTUREOr ~RE SOVXHER~r MALV~R~S. 157 and Lower Palaeozoic mass with its covering of ' Permian' and Trias, while denudation has largely removed ~his covering on the western side of the fault. The Southern Malverns may, then, be regarded as a portion of the front of an old mountain-range, more or less of the 5ura-type, the folds of which have been overthrown and overthrust westward. I have already maintained l that this range first arose during late Carboniferous times, and I hope to submit detailed evidence in supporb of this hypothesis on a future occasion. It finally follows that, if the views set forth in the foregoing pages be correct, we shall have to recognize in the crystalline rocks of the Malverns, not only an unmodified pre-Cambrian series of gneisses and schists, but also a newer series of schists fbrmed from the old material, and comparable in their secondary origin with those produced in Northern Scotland by the post-Cambrian movements.

IV. TrrE WwsTm~ T~ACT. The tract bounded on the east by Midsummer, Raggedstone, and Chase End Hills, and on the west by the May Kill Sandstone escarpment, falls naturally into three districts, which show certain physiographical and geological differences :-- (1) The district of White-leaved Oak, Pendock's Grove, and Coal Hill, which extends southward as far as Hayes Copse, at the south-western end of Chase End Hill. ~ (2) The district between Pendock's Grove and the gentle ridge on which Fow]et Farm and Martins are situated. (3) The district around Bronsil.

(1) The District of White-leaved Oak, Pendock's Grove, and Coal Hill. It is in this area that the geological structure is best shown. The strata have undergone comparatively little displacement, and exhibit a generally simple arrangement, well revealed in several picturesque glens which diversify the district. The only strata present in this district are the Malvern Black and Grey Shales, with which are associated series of igneous rocks, and a small patch of May Hill Sandstone. The Cambrian shales were termed ' Black Shales' by Phillips,2 but Hell 3 afterwards divided them into a lower series of Black Shales and an upper series of Grey Shales. Careful mapping shows that the Grey Shales occupy a much larger area than would be inferred from the current descriptions.~ 1 Rep. Brit. Assoc. 1898 (Bristol) p. 873. 2 Mere. Geol. Surv. vol. ii (1848) pt. i, p. 54. 3 Quart. ffourn. Geol. See. vol. xxi (1865) pp. 89 et se~q. Hell, op. c/g. p. 92; Symonds, ' Records of the Rocks,' 1872, p. 72, & ' Old Stones,' 2rid ed. (1884) p. 31. Downloaded from http://jgslegacy.lyellcollection.org/ at Orta Dogu Teknik Universitesi on January 17, 2016

158 :~nOF. ~. ~. 6RO0~ On WHr oroLoalcA~ [May i899 ,

In the locality now under consideration the Black and Grey Shales together form part of a fold the axis of which is directed north-westward, and the north-eastern limit of whichis overthrown and faulted against the Hollybush Sandstone and Archman (figs. 4-6 & 13, pp. 136, 144), while on the south-east the series is overridden by the schists of Chase End Hill, and, at any rate in the southern part of the district, inverted (fig. 16, p. 1"49). The best section in the district is that taken from the village of White-leaved Oak, south-westward down a little valley running between Pendock's Grove and Coal :Hill (fig. 13, p. 144). The Hollybush Sandstone at White-leaved Oak forms a steep slope on which many cottages of the village are situated (P1. XIV): the beds dip west-south-westward at a high angle. At the foot of the slope the Black Shales are seen, often much disturbed and generally inverted, so as to dip at an angle of 60 ~ or more in a north- easterly direction. The mutual dip of tile sandstone and shales towards one another can be explained only on the supposition that the junction is a fault,. A well-marked band of basalts interstratified with shales passes through the village, forming a round-backed ridge, the central line of which crosses the road immediately south-west of the village. This band is tripartite, there being three minor bands chiefly composed of basalts, separated by two thinner bands made up essentially of Black Shales. The Black Shales on the north-eastern side of this igneous baled have an inverted north-easterly dip, as seen in the fields north ~of the village. Those interstratified with the basalts are almost vertical, and those overlying the igneous band have a very high south-westerly dip. Traced south-westward, the :Black Shales are last seen at the northern corner of Pendock's Grove. Beyond this point the Grey Shales commence, and at their base are interstratified with basalt. This band, accordingly, forms a second well-marked ridge, separated from the first by a considerable depression occupied by Black Shakes with little or no igneous material. Igneous materials seem to occur almost everywhere in the Grey Shales along the rest of the line of section, but are specially developed 9only along a third ridge, passing through the middle of Pendock Grove, and forming Coal Hill on the other side of the g]en. Basalts occur in the lower part of this band, but the chief igneous rocks :are ophitic diabases; these are wcll-exposed in the garden of the 9cottage at the north-western end of Coal Hill. The interstratified shales and diabases here dip south-westward at an angle of 35 ~ Between the western foot of the Coal Hill ridge and the May Hill- 9 escarpment the Grey Shales can be traced along the ]ine of section by abundant ddbris only, and the determination of the exact position of the junction of the shales with the Llandovery Beds was a ~atter of difficulty, but was effected, I think, 9 some approach to 9 by the aid of excavations, and by noting the upper level to' whic, h the shale-ddbris extended. In the extreme eastern corner of the district traces of another Downloaded from http://jgslegacy.lyellcollection.org/ at Orta Dogu Teknik Universitesi on January 17, 2016

Vo]. 55.-1 sx~vcxu~z OF :rr~ SOV~HwR~ ~ALWRNS. 159

igneous band may be recognized forming, together with a strip of Hollybush Sandstone and the lowest Black Shales seen, the small spur running north-westward ik'om the north-eastern extremity of Chase End HiLl (see p. 149),

It will be seen from the foregoing description that, between the Malvern range and the Ma~ tti]l Sandstone escarpment, there is a great shale series, in which bands of igneous rock are intercalated at several horizons; and that, while near the Malvern range the l~eds are inverted so as to dip at angles of 60 ~ or less into the hills, a short distance away they become vertical, and then dip at a high angle in the opposite direction, and that still farther from the axis they assume a. somewhat low normal dip. The shales accordingly form part of a fold, the north-eastern limb of which is overthrown. We may, from an examination of the district, distinguish the following horizons in the Malvern Shales :-- (Upper Grey Shales. J Coal Hill igneous band. GaEv SrIXLES ...... ) Lower Grey Shales. [ Middle igneous band. ( Upper Black Shales. J Upper White-leaved Oak igneous band. BLACK SHALES ...... ] Lower Black Shales. [ Lower White-leaved Oak igneous band. Of these eight bands the upper seven can be traced more or less clearly over the whole of the sub-district, the three chief igneous bands forming well-marked ridges, which run uniformly from south- east to north-west, and the intervening shales forming equally well- defined but small strike-valleys, The course of the two upper igneous bands is interrupted, first by the valley along which the section in fig. 13 (p. 144) is drawn, and secondly by a less marked depression which, running about north and south, separates Coal Hill from the north-western slopes of Chase End Bill. The upper White-leaved 0ak band (1)1. XIV) forms the highest and most continuous of these ridges. It extends from the northern corner of Pendock's Grove for a distance of ~ mile south-eastward, where it abuts against the schists of Chase :End tIill, forming the northern part of the main spur of this hill. The surface formed by the Lower Black Shales slopes down somewhat steeply on the flank of Raggedstone Hill, but south-east of White-leaved Oak a deep hollow--the Valley of White-leaved 0ak--is excavated largely in these shales. The Upper Black Shales west of White-leaved Oak form a rather deep depression along the eastern border of Pendoek's Grove, while south of the village a slight depression only is observable. ' The middle igneous band forms a pronounced ridge extending :along the northern portion of Pendock's Grove, and, after a partial interruption by the main transverse glen, continues its course to a :point immediately beneath:the summit of Chase End Hill, the main spur of which it largely forms ...... Downloaded from http://jgslegacy.lyellcollection.org/ at Orta Dogu Teknik Universitesi on January 17, 2016

160 PROF. r. T. O1~O0~ On THE a~.OLOOrCAT. [May t899,

The Coal Hill igneous band forms a sharp ridge extending right across Pendock's Grove, a second shorter ridge known as Coal Hill, and an ill-marked tract of hummocky ground, constituting part of the north-western slope of Chase End Hill. At Coal Hill Cottage, as already stated, the dip is 35 ~ to the south-west. At the south-eastern end of Coal Hill the beds are vertical, and at the foot of Chase End Hill the uppermost beds of the series are inverted, so as to dip east-north-eastward at 45 ~. In the south-western part of the band, accordingly, the inversion of the beds may be traced as they approach the schists of Chase End Hill. The Upper Grey Shales form a broad band of greater length than the three last~mentioned zones. This extends from the north-western margin of Pendock's Grove to Hayes Copse on the south, a distance of about ~ mile. The surface of the median portion of the band is depressed, and the ground rises on the one hand towards the Coal Hill band, and on the other towards the May Hill Sandstone escarpment (fig. 13, p. 149). The only actual exposure of the shales is seen in the southern part of the district, near Hayes Copse, where the inverted beds dip east-north-eastward at 27~ no igneous rocks occur here. A solitary semicircular boss of basalt constitutes the only prominent igneous mass seen in the Upper Grey Shales of this sub-district. The northern corner of Pendock's Grove is occupied by a quadrangular block of May Hill Sandstone (M 355) and Grit (coarse sandstone), bounded on all sides by faults, which are more or less clearly defined by depressions of the surface. On it~ eastern side the sandstone is faulted against both :Black and Grey Shales, several of the zones of which strike up against it (see fig. 21). The

Fig. ')l.--Sevtion of Uambrian and Silurian rocks, between White- leaved O,]c and Fowler Farm. F ~ F N.W. I ~ II S.E. l

[Scale : 6 ineh~=l mile.] FF--Faults. [ a----Bl~k Sbale~ and basalts b=May Hill Sandstone. ] (Cambrian). rocks are exposed only at the extreme north-western corner of the patch. The fossils found among the d~bris include Lindstr~ia ~ubdupli(ata, Tentaculites, Orthis, and crinoids. A small patch of Black Shales, with associated igneous rocks (M 223), occurs on the southern boundary of the block. Downloaded from http://jgslegacy.lyellcollection.org/ at Orta Dogu Teknik Universitesi on January 17, 2016

Vol. 55.] S~aCCTVREOF T~ SOVT~SRX ~ALVSmXS. 161

(2) The District between Pendock's Grove, Martins, and Fowlet Farm. The district lying between Pendock's Grove and the gentle ridge extending from Rowick to the north-western corner of Raggedstone ]till is of complex structure, and at the same time of very imperfect exposure. It is almost exclusively covered with undulating pastures and arable land, in which practically the only rock-exposures are those seen on the top of certain rumps and small ridges formed by basalts and diabases intrusive in the Malvern Shales. These, with a number of small excavations made by the writer, and a few actual exposures of Malvern Shale, Llandovery rock, and Drift, together with the distribution of the d6bris of various kinds scattered over the surface, show that the district is a faulted complex of Black , Shales, Grey Shales, ~:[ay Hill Sandstone, and igneous rocks, covered in places by a stratified Drift. In the south-western park of the area the Upper Grey Shales are continued north-westward. Igneous rocks associated with them are seen in two small but conspicuous bosses (M 101 & 101a) near the farm known as Martins, and a smaller one (M 102) near Pendoek's Grove. This latter is shown by excavations to be connected with the small hill (M ]01a) along a gentle ridge running north-west and south-east : that is, in a direction agreeing with the strike of the beds in the Pendock's Grove district. The Coal Hill igneous band also appears to be continued for some distance into this district. An old quarry (M 103) is situated on one of the chief diabase-sills of this zone. The northern corner of the district is occupied by a patch of May Hill Sandstone and Grit, no exposures of which occur, but the presence of which is shown by excavations and by abundant d6bris. The patch is apparently bounded on all sides by faults, which separate the sandstone on the north-west from the Grey Shales, and from another block of May Hill Sandstone ; on the north-east, from the Hollybush Sandstone; on the east and south, from the Black Shales and associated igneous rocks. The Black Shales and igneous rocks on the eastern side of the block are apparently a continuation of the upper White-leaved Oak igneous band and Lower Black Shales. The igneous rock is exposed only at one point (M 157a), and the Black Shales are not exposed at all north of the road from Fowlet Farm to White-leaved Oak~ but their presence was indicated by some ddbris at one spot north of this road, and more, together with basalt, was reached in an excavation made near the hedge north-east of M 157a. Basalt (~ 175) ~ was reached, in excavations made for drain-pipes, in the northern angle between the sandstone-patches of Pendock's Grove and Fowlet Farm ; but it is uncertain whether this basalt is in place. The May Hill Sandstone patch east of Fowler Farm includes yellowish micaceous sandstone (M 153), purple grit (M 150), and 1 [Omitted from the map, P1. XIII.] Q.J.G.S. No. 218. Downloaded from http://jgslegacy.lyellcollection.org/ at Orta Dogu Teknik Universitesi on January 17, 2016

9162 P~o~. T. x. ~R00~ o~ THv, ~EOT.OaICSZ [May I899,

blue loam (M 151), 1 evidently resulting from the decomposition of fine argillaceous sandstone. The best section seen of the May Hill Beds was exposed in making a cistern (M 151 & 152) near the Fowler Farm cowshed. In this 2 feet of reddish-yellow soil passed down into 3 feet of blue clay, the upper part of which contained derived fragments of Hollybush Sandstone; the lower fragments were of argillaceous sandstone only, showing all stages of decomposition into blue clay: below this, a thickness of 3 feet of disintegrated purple sandstone was seen. The junction of the clay and purple sandstone was aft undulatory surface dipping mainly northward, but sometimes north-eastward, at an angle of 10 ~ or less. Both beds furnished fossils ; among these I recognized the following :-- JLindstr~emia subduplicata, M'Coy. Atrypa re~iculavis, Linn. L. s. var. crenulata. _Pentamerus sp. Favosites asper (?) d'Orb. S~ricklandinia lens (?) Sow. JLeptoceelia hemisph~rica, Sow. _Pterinea sp. ~trophomena anti~uata, Sow. Ousteropods. Orthis calligramma, ])aim. Tentaculites anglicus, Salt. Orthis sp. Orthoveras sp. ~pi~ifera elevata, Dalm. Encrinurus punctatus, Briinn. Spirifera crispa, His. Crinoids.

The existence of Llandovery rocks in the neighbourhood of Fowlet Farm was known to Phillips, Hell, and Symonds. Phillips 2 said: ' There are beds of true Caradoc sandstone (No. 6), with fossils in tolerable plenty, near Fowler Farm, thrown down by some obscure but powerful displacement, or deposited unconformably.' Hell" and Symonds 4 regarded the patches here, and to the north, as outliers resting unconformably upon the Cambrian rocks. That these patches are in reality blocks faulted into the Cambrian is evident, first, because not only do the basaltic ridges and interstratified shales strike directly towards the sandstone in such a way that it cannot be supposed that the latter overlies the shales (fig. 21, p. 160), but the sandstone itself appears to strike up against the shales; secondly, the rectilinear boundaries point towards the same conclusion; and finally, to all appearance, the Llandovery Beds in the escarpment to the west dip in approximately the same direction, and probably at nearly the same angle, as the underlying Grey Shales (see p. 167), wherefore the basal beds of the escarpment would pass far above the sandstone of the patches (fig. 13, p. 144). The geological structure of that part of the district which lies between the igneous bands of the Grey Shales and the May Hill- Sandstone patches Of Fowler Farm and Pendock's Grove is by no means clear. The chief exposures consist of igneous rock. A well- marked circular boss of basalb (M 104) occupies ~he angle between the two patches of sandstone, and a smaller boss (M 124 & 125) is seen west-north-west of this. In the road, 30 yards south-south-east 1 [Marked 157 on the map, P1. XIII.] 2 Mere. Geol. Surv. vol. ii (1848) pt. i, p. 54. 3 Quart. Journ. Geol. Soc. vol. xxi (1865) p. 94. 4 Proe, Geol. Assoc. vol. iii (1873) p. 269. Downloaded from http://jgslegacy.lyellcollection.org/ at Orta Dogu Teknik Universitesi on January 17, 2016

u 55.J S~RVCTUREOF Tg~, SOUTH~.R~ ~t~LV~.R~S. 163

vf the cottage immediately west of Fowler Farm, a porphyritic basalt (M 356) is exposed in the hedge-bank; and Fowlet Farm itself is situated on similar basalt (M 451). A considerable hump of an oval shape (M 224 .~ 198) is situated south of M 104. The rock itself is not exposed here, but the ddbris abounding on the surface of the ploughed field which covers it indicate the presence of much basalt. Diabase (M 447) 1 is exposed onthe road between Fowler Farm and the cowshed south-east of this, and the cottage immediately west of Fowlet Farm is situated on another patch of diabase (M 372), well shown in the road.

The shales with which these igneous rocks are associated are very imperfectly exposed; thearea north of the igneous bosses near )lartins is covered by a thick deposit of Drift, and excavation in the lower ground failed to reach the rock. Much indurated shale of a light colour, such as is found in connexion with the igneous rocks in both the Black and Grey Shales, occurs with the basalt of M 224 & 198, but no unaltered Black or Grey Shale was seen here in sufficient abundance to enable me to determine whether the basalts belong to the Black or to the Grey Shales. In a little hollow, however, immediately west of ~ 224, generally occupied by a pool, Black Shales are seen dipping west by south at 30~ . These appear to be faulted against the Coal Hill igneous band, which is seen immediately to the westward. This suggests that the basalts on the north-east are also in Black Shale. Black Shale occurs associated with the basalt at M 356. A well sunk many years ago, to a depth of 84 feet in the orchard of the cottage west of Fowlet Farm, and immediately south of the alia- base M 31.., showed, as I am informed by the cottager, nothing but Black Shale and' yellow stuff' (perhaps weathered basalt or diabase); and in a trench cut across the orchard a short time ago I observed a great quantity of disturbed Black-Shale ddbris, almost certainly thrown out from this well. An excavation (M 194) made many years ago south-west of the well, apparently in search of coal., shows abundant ddbris of Black Shale, and similar fragments seen in the hedgerow seem to connect this patch with that of the well. These occurrences indicate the existence of one or more faulted blocks of Black Shale in the district. Possibly, all the igneous masses 9enumerated above belong to two or three such patches, and as such I have provisionally mapped them, though it must be clearly under- stood that this point is by no means certain. The northern slope of the ridge between Fowlet Farm and Martins is largely formed by the Grey Shales. These are exposed in the main road north of Fowlet :Farm, where the beds dip irregularly in a northerly direction at a low angle. West of this point, and directly along the line of strike of the Coal Hill igneous band, is a quarry in a mass of diabase (M 106) crossing the road. D~bris of the same rock associated with indurated shale may be traced up the 1 [Omitted from the map, P1. XIII.] ~2 Downloaded from http://jgslegacy.lyellcollection.org/ at Orta Dogu Teknik Universitesi on January 17, 2016

164 woF. x. T. G~OOM O~ XHV, ~mr, O~ICAT. [May I899 , slope to the south-east. On the top of the ridge, immediately south of the road between Fowler Farm and Martins, an excavation revealed Grey Shales dipping south-westward at a low angle. The diabase and indurated shale-ddbris seen in the neighbourhood doubtless represent the north-western continuation of the Coal Hill band. The excavation at M 194 which furnished Black Shales contains a remarkable breccia, of which many fragments may be collected from beneath the turf, but neither shales nor breccia can be now seen in place. A very similar breccia with red sandstone (M 176) was reached in making a trench for pipes to the cistern (M 151, 152), and may also be seen in place close to the hedgerow near the cowshed. The breccia is made up of alternating layers of fine and coarse material: the dip of these layers is difficult to determine, as very little of the rock is exposed, but I suspect that the beds are approximately horizontal. Immediately north of ibis breccia were turned out the blocks of basalt (M 175) to which reference has already been made (p. 161). The breccia is quite different from anything else that I have seen in the Malvern district, and I have so far been unable to determine with certainty whether it is a sedimentary rock at all. It consists chiefly of angular fragments of rocks, all of which can be matched in the neighbourhood ; many of the fragments are subangular, and a i~w well-rounded. The sandy matrix is thoroughly impregnated with an abundant cement of limonite. This rock will be more fully considered in a future communication, containing an account of the lithology of the Malvern range. At present, I see no reason for placing it among the Palaeozoic rocks of the district. A description of the horizontal beds of Drift which cover most of the low ridge between Fowler Farm and Martins is likewise deferred.

(3) The District around Bronsil. The Bronsil district appears to be composed exclusively of Cambrian Grey Shales, with the associated igneous rocks, May Hill Sandstone, and Drift ; but most of the area forms pasture-land, with very few rock-exposures. The Grey Shales occupy the greater part of the district, as shown by exposures, excavations, and shale-ddbris. Points at which there is a reasonable certainty that the Grey Shales occur are indicated by a symbol (• in the map (P1. XIII), or by an arrow showing the amount and direction of dip, where these could be taken. The exposures of igneous rock in this district are few. They consist, first, of a rather thick band of diabase that crosses the main road between Hollybush Pass and Eastnor (M 106) ; this is apparently continued as far north as Beacon Farm, close to which a small exposure of diabase (M 171) is seen. Another small patch of diabase (M 454), associated with much indurated Grey Shale, was Downloaded from http://jgslegacy.lyellcollection.org/ at Orta Dogu Teknik Universitesi on January 17, 2016

Yol. 55.] sT~vc~u~ o~ 'ru~ sovrnER~ ~A~.VE~NS. 165

reached in excavations kindly made for me by Mr. Summers in a field south-east of Beacon Farm. There are, secondly, a series of bosses of basalt forming rumps numbered M 159a, M 108, M 249, M 248, & M 247. These tumps have an elongated form. The axes of M 159a & M 108 are directed about north and south ; that of M 249, north-east and south-west; that of M 248, north-west and south-east; and that of M. 247, east-north-east and west-south-west. These bosses were supposed by 1)hillips to occur between the ~[alvern Shales and the May :Hill Beds, but mapping shows clearly that they are situated in the Grey Shale ; for beds belonging to the latter series occur between the bosses and the escarpment, as clearly seen to the west of M 159a ; and, in the case of M 247, the basalt is actually seen to be overlain by Grey Shale. It can hardl); be doubted, from the analogy of the basalts farther south and from the few dips seen in the northern district (for instance, at M 159), that the direction of these short ridges of basalt marks that of the strike of the beds. The separate exposures, moreover, appear to be all approximately on the same horizon, with the possible exception of ]~I 247, which may mark a higher horizon. In this northern district, then, a curved igneous band, consist~ing of basalts (and diabase)extends from Beacon :Farm almost as far as Castle Coppice, and, judging from the configuration of the ground, it is connected with the diabase in the main road (M 106) by a concealed mass of similar rock. This band is undoubtedly a northern prolongation of the Coal Hill igneous band, which it resembles in being overlain and underlain by Grey Shales containing Dictyonema sociale.

The eastern part of the Bronsil district is occupied by May :gill Sandstone, allusions to which may be found in the works of Phillips and tIoll. The 5Iay :gill Beds at the north-eastern corner of the area are apparently a south-easterly continuation of those which form the north-western corner of Midsummer ~[ill. The sandstone in this locality, like that elsewhere in the Bronsil district, is nowhere actually exposed, and can be reached only by excavations. This sandstone is evidently separated from that forming the escarpment by a fault, which probably runs along the bottom of the valley traversing Castle Coppice; for the beds exposed in the escarpment on the western side of the valley are the basal beds of the series, and dip at a considerable angle west-north-westward, while those under consideration are grey beds belonging to a higher part of the formation. A second faulted patch of May Hill Sandstone occurs to the south. An excavation (M 192) close to a spring revealed Llan- dovery rock with StricTclandinia sp., and a second excavation (M 113) made a little to the north-west of the first furnished Downloaded from http://jgslegacy.lyellcollection.org/ at Orta Dogu Teknik Universitesi on January 17, 2016

166 PR0~. T. T. aROOX O~ Tm~ O~OLOGIC~n [May I899r

Pentamerus (or Stridclandinia) sp., I, eptoceelia hemisphcerica (?), crinoids, and a trilobite. From d6bris a little south of Castle Coppice (M 114) I obtained the following fossils :--Leptocoelia hemisTha~rica , Dinobolus sp., Pe~v- tamerus sp., Beyrichia complicata, Favosites (?), and crinoids. The dip of the sandstone could not be determined. A third, much smaller, patch of May Hill Sandstone was revealed' by an excavation made between Bronsil and Upper House Farm. The dip here was north-westerly at a low angle. The Grey Shale forming the rising ground east of Beacon Farm: is covered by a Drift similar to that mentioned on pp. 161, 163.

In considering the Bronsil area, it remains to be pointed out that, though the observed facts agree fairly well with the view that: the strike of the Grey Shales, when traced from south to north, gradually curves round from north-west through north to north- east and south-east, the area occupied by the shales must be traversed by some fault or faults tother than those indicated in the map, P1. XIII) cutting out the Black Shales; for, supposing the latter to form a similar curve, they ought to appear both south, west, and north of Upper House Farm, whereas in reality Grey Shales are found everywhere in places not occupied by May Hill Beds. It is not sufficient to suppose that the blocks of May Hill Sandstone are simply let down into the otherwise undisturbed Malvern Shales ; some faulting-down of the Grey Shales themselves in the eastern part of the area must have occurred. It may, lastly, be observed that igneous rocks appear to be much less developed in the Bronsil area than in the two districts to the south. No traces are visible of the middle igneous band, and there seems to be little reason to believe that this is present, but not exposed, for the basalts make a very distinct physiographical feature in the Pendock's Grove area; whereas smooth low ground appears in the Bronsil district in places where these rocks might be expected to occur. This igneous band seems either to hayer died out towards the north, or to have been faulted out, together with the Black Shales. The relative insignificance of the Coal Hill band rather favours the former hypothesis.

V. T~z MAY HILs, SANDSTONE ESCARPMV,I~T. The escarpment forming the western boundary of the Cambrian- shale district extends from Castle Coppice on the north to near Hayes Copse on the south. For most of its length it rises sharply from the adjoining lower ground, but between Martins and Hanging Lift, and again south of High Wood, the slope is gentler. It is interrupted at two points by small transverse valleys which give passage to streams : first between Bronsil Lodge and Wain Street, and secondly south of Rowick. The dips (as shown on the map, P1. XIII) and the strikes of the beds correspond approximately, so far as they are visible, with the Downloaded from http://jgslegacy.lyellcollection.org/ at Orta Dogu Teknik Universitesi on January 17, 2016

Vol. 55.] STRVC~UREOr ~r S0UTHERN MArVrr:~S. 167 semilyrate form of the escarpment. The actual junction of the Llandovery Beds with the older series is nowhere shown, but its position can, in most places, be fixed within narrow limits. The beds immediately underlying the Llandovery Sandstone and Conglomerate along the whole length of the escarpment are the Grey Shales, or possibly, south of Martins, igneous rocks associated with them. Only in Castle Coppice is this natural junction replaced by a faulted one; a block of Llandovery Sandstone is here brought down against the basal Llandovery Beds of the escarpment. It is important to note that the strike of the Grey Shales is generally about parallel to that of the May Hill Beds above, the former evidently turning round through all the marked curves shown by the latter. In the absence of any exposures of the junction, it is impossible to say to what extent the amount of dip of the two series differs. The complete absence of the Ordovician formations from the district would prepare one to find a marked difference in this respect. The dip of the Grey Shales, however, in the Bronsil district (where the sandstones are best exposed) varies generally from 15 ~ to 48~ that of the adjacent Llandovery Beds ranges from about 17 ~ to 60 ~ South of Bronsil the shales dip at an angle of 40 ~, while the sandstone not far away dips at an angle of 48 ~ These facts would seem to indicate that the dips in both series are of the same order, and that, were actual junctions exposed, the discordance between the two might not be perceptible in a single section. Moreover, the behaviour of the line of junction as it crosses the contour-lines (see map, P1. XIII) can hardly be explained otherwise than by supposing that the plane o[ junction of the sandstone with the shales dips everywhere into the escarpment, at an angle approximately equal to that of the dip of the May Hill Series; or, in other words, that the Llandovery Beds overlie the older series, with probably apparent conformity. In this connexion it must, however, be noted that, if (as is practically certain) the main igneous belt in the Bronsil district corresponds with the "Coal Hill band of the districts on the south- east, the beds of this horizon are appreciably nearer the escarpment in the northern than in the southern part of the ' Western Tract.' The line of igneous bosses in the Upper Grey Shales (M 101, 101 a, & 102) approaches very near the escarpment south of M:artins, wMle on the north there seem to be no indications of its existence, unless )~ 247 denotes its reappearance towards the east. This zone has probably passed underneath the May Hill Beds north of Martins. Moreover, the area occupied by the Upper Grey Shales broadens out towards the south, as seen south of Coal Hill. These facts probably indicate that, as the unconformable junction is followed from north to south, newer beds belonging to the Grey Shales gradually make their appearance, the Llandovery Beds slowly overstepping the zones of the Grey Shale when traced northward. On the other hand, there is no evidence of an overlap of the Downloaded from http://jgslegacy.lyellcollection.org/ at Orta Dogu Teknik Universitesi on January 17, 2016

168 P~oF. ~. ~. aRoo- o~ ~E ~,OT.O~IOAT. [May i899,

Llandovery Beds when traced towards the :Malvern range itself (that is, towards the east), for near the southern end of Chase :End Hill, and near Castle Coppice, close to Midsummer Hill, the Llan- dovery Beds rest on zones of the shale as high as, or higher in the series than, the shales beneath the escarpment near Bronsil. The current statement that the Llandovery Beds transgress across all the Cambrian zones into the Arehman must, therefore, in my opinion, be modified.

It is proposed to supplement the present communication by further papers dealing with other portions of the Malvern and Abberley ranges, and with the stratigraphy, pakeontology, and lithology of the rocks considered.

~XPLANATION OF PLATES XIII-XV. PLATE XIII. Geological Map of the Southern Part of the Malvern Hills, on the scale of 4 inches to the mile. PLATE XIV. View of Raggedstone Bill from the south. The observer is supposed to be standing on a spur of Chase End Hill (at the spot marked 269 in the map). The village of White-leaved Oak is per- ceived near the middle of the view, situated partly on an igneous band which fbrms the series of gentle swellings running south and north-west of the houses seen. The western edge of this ridge is seen to the left of the haystack, and in the distance is marked by a large tree at the northern corner of Pendock's Grove. The eastern limit of the Black Shales is marked approximately by the trees at the top of the field on the western slope of Raggedstone Hill. The Hollybusb :Sandstone forms most of this slope, the upper limit being indicated approximately by the top of the sharp ridge above the village, and by the trees farther north-west. The depression marking the axial thrust-plane is well seen beyond this line, passing between the two summits of the hill.

PLAT~ XV. Yiew of the Hollybusb Pass and Midsummer Hill, from the hollow known as Winter Combe, on the northern slope of Raggedstone Hill. The axial depression forming this hollow is continued beyond the pass to the left of the quarry (schists) between Hollybush Hill on the right and Midsummer Hill on tl~e left. The observer is standing on the small quartzite-ridge, the chief rock-exposure of which occurs by a small hollybush seen in the bracken. To the left of the houses, near the centre of the view, is seen the bank in which the May Hill Sandstones are faulted against the Areh~an diorite. Discussion. Dr. HIcKs said that the faulted conditions at the margins of the crystalline rocks in the Malvern Hills agreed in a marked manner with those along the borders of the pre-Cambrian crystalline rocks at St. David's and in other areas in Wales. Before Hell showed that these rocks in the Malvern Hills were of pre-Cambrian age, they were supposed to be metamorphosed Cambrian sediments. Similar rocks in Wales were stated to be either mebamorphosed Downloaded from http://jgslegacy.lyellcollection.org/ at Orta Dogu Teknik Universitesi on January 17, 2016

~ol. 55.] s~vcvvaE or ~r~ sov~R~ ~xT.w~s. 169

deposits of Cambrian or Silurian age, or intrusive masses invading Cambrian or Silurian rocks. In each case, the mistake seems to have been mainly due to the fact that the observers had failed to recognize the remarkable results produced by faults and crushing', not only on the sedimentary beds in the immediate neighbourhood of the pre-Cambrian crystalline rocks, but also on the latter, during intense movements in the earth's crust. Prof. SOLT,XS remarked that ever since Phillips had made the ~[al~erns the base of the district described in his 'Geology of Oxford & the Valley of the Thames,' those mountains had been a source of peculiar interest in Oxford, and the Author's work had been looked forward to with great expectations, which the paper of that evening had more than satisfied. It presented them with ~n epitome of mountain-structure, logically worked out, even the transverse fractures, which must necessarily result in crust- folding, receiving the attention which they merited, but rarely obtained. The examples of' basalt' exhibited did not appear to be typical examples of that rock ; and since nearly every petrographer used the term ' diabase' in a different sense, the speaker thought that this name should not be employed without some qualification. With regard to the nodes and internodes of the West :English chain, it was possible that the two systems of crossing folds which produced them might have been simultaneous, and not successive. Prof. Wx~TS referred to the igneous rocks associated with the Cambrian rocks of the ~]~alvern tti]ls, and noted their resemblance to those originally described by Allport as diorite in Warwickshire. Similar rocks occur in association with Cambrian strata at Nuneaton, the Longmynd, the Wrekin, and in the Northern Itighlands. The PR~S~E~, Prof. LAPWOaTH, Prof. Bo~,r, and Prof. HwL also spoke. The Aw~oR said, in' answer to Prof. Sollas and Prof. Watts, that the terms ' basalt ' and ' diabase ' were employed in the sense used in Hr. ttarker's ']~etrology for Students.' To Prof. Lapworth he replied that he hoped to deal ia a later communication with the movements which the Malvern chain had undergone.