200

SECOND DAY.-EXCURSION TO BRIDPORT, BOTHEN­ HAMPTON, BURTON BRADSTOCK, BRIDPORT HARBOUR, AND EYPE.

(Report by HORACE B. WOODWARD.*) On Tuesday morning the party started a little before ten o'clock from the Bull Hotel at Bridport, after being joined by a small detachment of Members who came from Yeovil by an early train. The weather was dun and misty, so that Colmer's Hill, a conical knoll 370 feet high, formed of Inferior Oolite Sand, and usually a conspicuous feature in the landscape west of Bridport, was only just visible as the members passed the Market House. Proceeding along South Street towards Bothenhampton, the evidences of terrace-cultivation were noticed on the hills east of Bridport. Here in some cases narrow strips of cultivated land, still enclosed by hedgerows, fringe the higher slopes of the hills, ranging one above the other, and varying in length, breadth, and inclination. Rarely the strips stretch across the hills, as indicated by hedge­ rows still remaining near Walditch i but in other cases, where no hedgerows exist and the land has been turned into permanent pasture, the slopes present the remarkable features called " linchets " or ,. balks," which are simply the banks or ridges which formerly divided the strips of cultivated land. They are of some geological interest, as they occasionally exhibit a resemblance to parallel terraces, and they have actually been described as raised beaches! t Such terraces are of frequent occurrence along the Dorset coast, in the Isle of Purbeck, and near Abbotsbury, as well as near Bridport and on the slopes south of Burton Bradstock: many, too, have been noticed in other locali­ ties. While in some cases such appearances may be caused by Iandslips, yet there is little doubt that the majority of these terraces were, as pointed out by Mr. G. Poulett Scrope, "worn by the plough at a time when these slopes were, if they are not still, under arable cultivation." For he remarked that the " down-hill tendency of the disturbed soil is greatly assisted by the wash of

II Much of the information here given has been collected during a re­ cent examination of the district for the Geological Survey. It is here prmtod, in advance of the official publication, by permission of the Director-General.-H. B. W. t See D. Mackintosh, • Geol. Mag.,' Vol. iii, pp. 69, 155; and' Scenery of England and Wales,' 1869, p. 84. EXCURSION TO BRiDPORT, BOTHENHAMPTON, ETC. 201 heavy rains upon the sloping surface, and the result is that, year by year, the whole surface-soil of the slope, when und er continuous arable culture, is slowly, indeed, but surely, travelling downwards until it is stopped by some hedg e, or wall, or bank, which limits in a downward direction th e disturbing action of the plou gh." '* The writer remarked that on th e I sle of P ortland, where freehold land ba s been divided and subdivided, narrow strips of land arc ofton cultivated j and , near the high er lighthouse, lie had noticed in a breadth of about a quarter of a mile no less than 35 strips of land on which crops of corn, grass, and potatoes were alternately grown. In such a tract, when arable cultivation is succeeded by pasture, no doubt It series of ridg es or " terraces " will mark the change that has taken place. Passing through Bothenhampton, the Members proceeded to the quarries in the Forest Marble, situated to the south of the village. Here this formation is seen dipping to the northwards, towards the Middle Lias, against which it is faulted. The fault is no doubt a continuation of the disturbance (to be mentioned further on) which brings the same formations in abrupt contact to the east of Eype's Mouth, where the downth row must be at least 425 feet. The hill side south of Bothcnhampton is scarred with old pits from wh ich the Forest Marble bas been raised for many years past, the stone having been worked on a dip-slope. Here three main divi­ sions in the formation ar e to be observed- an upper division of shales and shaly limest one, with thin beds of shelly limest one ; a middle division of shell-limestone (about 12 feet of which was expose d) ; and a lower divisi on of shales and thin lim estones. The junction with the basement beds of the Oornbrash may be seen in a lan e-cutting south of Bothenbampton church, where grey sandy lim est ones and marls, with Aviwla ecliinata and many brachiopods, rest on flaggy shell-limestones and clays that form the upper part of th e Forest Marble. Th e main mass of stone for which the Bothenhampton quarries have been opened is a blui sh-colour ed oolitic and sh elly lim estone, very much false-bedded. This rock, known as " B'ampton Stone:' is used for building purposes, and for road-mending, and sla bs are obtained for piggeries and for stiles. It is too much impregnated with ochreous galls to be useful as marble. Prof. A. H. Church

II 'Geol. Mag.,' Vol. iii, p. 293. 202 E XOURSION TO BR ID POR T, nO THENHAUP TON, ETO . is of opinion that iron-pyrites has originally been th e colouring material of the blue bands of the Forest Marble, and that the yellowish-brown exterior is dne to the oxidation of the pyrites.* Among the fossils to be observed in the ston e arc Pecten lens, P. vagans, Lima duplicata, L. cardiiformis, Ostrea Soioerbui, Cyprilla L oweana, and Apiocrinus P ark insoni,t J oints of th e last-named fossil, termed " Coach-wheels," are not uncommon. Some reptilian bones have also been obtained, as well as fragments of lignite. Curious markin gs are abundant on some of the sur­ faces of th e sandy limestone-shales, and th ey appear to be tracks of invert ebrate animals. It was pointed ont that the Great Oolite developed near Bath and for some distance to the south of that city does not occur so far south as Dorsetshire, being represented perhaps in part by th e Forest Marble, and in part by the Fuller's­ Earth. Pa ssing up a narrow and somewhat dirty lane, th e Members now ascended by some old quarri es to th e top of the hill. Here a splendid view of the country was unfortunately eclipsed by the mist. The scenery is indeed diversified, and in clear weathe r th ere appears at first to be little system in the arran gement of hill and vale. 'l'his is in part dne to th e overlap of the Chalk and Uppe r Gr eensand over the Jurassic rocks, the newer strata resting on different members of the latter series j and the irregul arity in the features is also in part due to the faults which here and there have displaced the Lia ssic and Oolitic rocks. Apart from th e general influence of stratigraphi cal arrangement, the influence of lithologi­ cal characters is likewise mark ed. The Greensand, as u rule. stands out boldly, forming the gorse-clad hills of Eype Down and Ship­ ton Beacon, and, further off, th e" Alps of Dorset," or P illesdon P en and Lewston HilI , known to sailors as the" Cow and Calf." The flat-topped hills, capped by In ferior Oolite, are readily distin­ guished from th e grassy knoll s formed of the Oolite Sands ; while th e well-cultivated tracts of the Middle Lias, marked by small enclosures and famed for orchards, appear in contrast with th e wet and less productive t racts of Fuller's Earth or F orest Marble.

* 'Quart. Journ. Chem, Boc.,' Seri es 2, Vol. ii, p, 379. t The fossils menti oned in this paper, except where otherwise stated, were identified by :Messrs. G. Sharman and E.T. Newto n. See also Wrigbt, • Qnar t. J ourn. Geo1. Soo.,' Vol . xii, p. 310; and Damon, • Geology of Wey. month, ' &0" 1884, p. 223. ltXCURRION TO BRIDPORT, ROTHENHA!>!PTON, ETC. 203

About half a mile west of Burton Bradstock a small quarry in the Inferior Oolite was visit ed. Th e bed s here work ed belong alui ost entirely to th e zone of Ammonites Parkinsoni, represented by pal e gl'pY oolitic and sandy lim estones, below which n bell occnrs in which Bra chiopoda ar e as abundant (s o one Memb er ob­ served) as " plums ough t to be, in a pudding." Ter ebratula splus­ roidalis is the comm on form. Other fossil s met with in th ese beds ar e RJ,yn chonel/a spinosa, Terebratula Phillipsii, 1'. glubata, and Waldheimia carinata. *' Echinoderms, represented by Oolinrite» rinqens and .lIolecl!J[llis tiemisplue ricus, are not uncommon. Ammo­ nites Humpliriesianus occur s in th e Terebratula bed, and als o in the iron-shot limestone exp osed at th e base of the quarry. To the south of this pit, on the northern slope of the hills stretching towards Bridport Harbour, are several old pits, exca­ vated for the most part in the brown, and sometimes blue, iron­ shot limestone which forms th e lower portion of the Inferior Oolite of this district. He re the stone has been largely us ed for building the wails which divide th e fields. In these beds Ammo­ nites Mur chisonai has been found, and Waldheimia carinata is 11180 more abundant than in the upper strata. Th e Memb ers now descended the hill, and taking a footpath through th e meadows, crossed the little River Bredy, and p ro­ ceeded to the deep road-cutting south of Burton Bradstock. This excavation was made about three years ago, and it sh ows nearly the whole of the Inferior Uoli te (h ere about 15 feet in thickness), and th e junction of it with the 8ands beneath. Many fossils were obser ved, although, owing- to the difficulty in extracting th em, if not to the fear of injuring the banks, few were collected. The entire Oolite is here l\ .. Cephalopoda Bed j" but the so-called Cephalopoda bed of th e Ootteswold Hills is no doubt represented by th e upp er portion of th e Sands beneath. The lowest portion of this Oolite represents in the broad sense the zone of Ammonites Murchisonce (including the beds with A. concavus) ; the highest portion represents the zone of Ammonites Parkinsoui, Th e zon e of Ammonites Humphr iesianus, which is to be found in some quarries east of Bridport, does not appear to be distinctly developed at Burton Bradstock, although the species is met

* The Brachiopoda from the Inferior Oolite of this district have been figured by Dr. T, David son in the' Proc. Dorset Nat. Hist. Fi eld Club,' Ui77. See al so Wright, • Quart. JOUl'U. Geol. Soc.,' Vol. xvi, p. 47. 204 EXCURSION TO BRIDPORT, BOTHENHAMPTON, ETC. with in the cliffs and road-cutting.v Dr. M. Poignand, a Member of the Association, who visited the neighbourhood while the road­ cutting was being made, obtained many Ammonites from it as well as from the cliffs. They included A. Ma,·tinsii, A. Parkinsoni, A. Humphriesianus, A. subradiatus, A. fuscus, A. dimorphus, A. poly­ morphus, A. (Ieroillei, A. Garantianue, A concavus, a variety like A. concavus, A. Aalensis, A. MurchisonaJ,A. Sowerbyi, val'. gingensis, and A. confusus, S. S. Buck.t Rhynchonella cynocephala has also been found at this locality, in tumbled blocks of the sandy strata. Descending now to the beach, the general aspect of the cliffs attracted the attention of the party. To the east a grey cliff of Fuller's Earth capped by Forest Marble was seen to extend about half a mile towards Oliff End, the last of the sea-cliffs this side of Portland. ,To the west the yellowish-brown cliffs of sands pre­ sented a curiously picturesque appearance, the many bands of sandy limestone standing out in relief from the softer sands, which more readily yield to the destructive influence of the weather. Here and there a smooth face of cliff told of recent slips, the traces of which in several cases had been removed by the sea. A slight inward dip here helps to keep the cliffs perpendicular, as in tbe similar cliffs which extend on the other side of the River Bredy to Bridport Harbour. In those cliffs the capping of Inferior Oolite is very thin. (Fig. 2.) The beach of fine shingle which extends along the base of the cliffs now drew forth some remarks. This shingle is identical in composition with the beach at Ohesilton-indeed it may be said to be the western extension of the famous Ohesil Bank, whose pebbles at Portland are three or four inches in diameter, while here they are reduced to one-half or one-quarter of an inch. In this fine shingle one may detect, in addition to the numerous pebbles of Ohalk flint and Greensand chert, red and brown quartzites and hard sandstones (probably Devonian), and minute Budleigh " poppIes," as well as tiny pebbles of igneous rocks. These rolled fragments of rock have come from the west, being derived, as Sir John Coode has pointed out, chiefly from strata developed west of Lyme Regis. Much of this material evidently travels at some distance from the coast, across Lyme Bay, and being stopped by Portland, the larger

* For remarks on Burton Cliff,Bee Wright,' Quart. Journ, Geol. Soo.,' Vol. xii,p.311. t These Ammonites were identified by Mr. E. T, Newton. EX CURSION TO BRIDPORT,BOTHENHAMPTON, E TO. 205

pebbles are heaped up there. The eddy tid e produced by th at pro­ II montory serves to divert the tra vel­ ling of th e shingle, so that the pebbles are driven westwards again along the beach, and by " wear and tear" gradually diminish in size until we reach Bridport Harbour and Eyp e. W est of Eype th e shingle ordinarily trav els from west to east . • The Director was of opinion that th e pebbles could not have been mainly derived from the old raised beach, of which a remnant is found at Portland, as suggested by P rof. Prestwich, because tb e pebbles on the Chesil Bank under Portland were much larger than those which made up th e mass of the raised beach-shingle at P ortl and Bill." Notwithstanding th e interest at­ tached to this beach, the members appeared glad that only a mile of it bad here to be traversed. On ~ ~ approaching the River Bredy the 0 0 0..0 small fault in the cliffs was noti ced .",'" ~~ (F ig. 2.),t as well as the capping of Full er's Earth clay. Here many .~ '0 tumbl ed blocks of rock afforded o material for the collector, tho In­ ferior Oolite being otherwise inacces­ sible in the cliffs. From such tumbled .. blocks most of the fossils have been

* See paper on the • Origin of the Chesil Bank,' by Prof. J. Prestwich, • Proc, lust. Civ. Eng.,' Vol. xl, 1875. Refer ences to other papers will be found here. See also Dam on, • Geology of Wey mouth,' &0., 1884, p. 167. t The part of the section to the west of thi s fau lt is somewhat exaggerated in the figure- t he Fuller's Earth being only just visible on the upthrow side of the fault. 206 ItXCURSION TO BRIDPORT, JlOTITENHAMPTON,ETC. procured for which Burton Bradstock is noted; and here it may be menti oned that persons living at this village who collect specimens for sale unfortunately mix up th e fossils found on either side of the gangway at Burton Bradstock, H ence Rhynchonellas and oth er fossils of the Forest Marble or F uller's Earth are apt to be commingled with th ose of the Inferior Oolite. The jun ction of Inferior Oolite and Sands was noticed hy Mr. Hudleston in one hnge fallen mass of rock, and here small varieties of Ammonites Humphrieeia.nus were found in th e 'I'orebratnla Bed, at the base of th e strata containing Am monites Parkinsoni . These beds rest on abont five feet of coarse iron- shot oolite, in which Ammonites concaous is th e more abundaut form. Am ong other species obtained from th e Oolite were A sta/'te obliqua, M.ll neitea tenuistria , Lima pectiniformis, and Triqonia ; and one Member obtained a species of Oidaris.* Th e River Bredy, which sometimes filters through the shingle into th e sea, was now rendered strong enongh by recent heavy rain s to work a channel out to sea, and it was too swollen to allow th e Members even to leap across, so returning a little way to th e foothridge th ey took the path over the hills to Bridport Harbour. A short and welcome hal t was made at the Neptune Hotel, and the party then proceeded along the beach to the westward . The fine shingle east of th e harbour is extensively dug and sent away for making paths, for concrete, &c.; but the material taken away is said to be readily replace d by th e sea. West Cliff,t Bridport Harbour, is for the most part a grey cliff form ed of crumbling marl, capped by limestone and clay, rising to a height of nearly 200 feet, and of a most treacherous nature; for the cliffs are perpendicnlar or even overhanging in places, and frOID th eir soft nature frequent slips take place . The grey marl is th e Fuller's E arth which is faulted at the eastern end of th e cliff llgainst the Oolite Sands, and at the western end again st th e Middl e Lias. In both cases th e faults run in an easterly and west erly direction. Thus where the sands occur, they present a face of rock ag ainst tbe Fuller's Earth, and

* On tb is subject see Wril{ht, I Quart. J rmrn . Geol. Soc.', Vol. xii, p. 311; Day, tu«, Vol. xix, p. 287; Whidborn c, i u«, Vol. xxxix, p. 487. See also Damon, ' Geology of Weymouth,' &0., 1884, p, :!18, and Section by R. Etheridge, p. 2:!6. t Known also as Watton Hill and Pourfoot Hill. EX CURSION TO BRIDPORT, BOTHENHAMPTON, ETC. 207 this low cliff of sands gradually descends towards the west to the sea-level, beyond which the beds have been destroyed by the ravages of the sea ( Fig. 2,). At low water, however, ledge of th e indurated bands in th e sand OIay be seen j while on the coast, blocks of fossiliferous rock occur, portions of Inferior Oolite, which appear to have been wedged in along the line of fault. The Fuller's Earth is a marl with beds of impure limestone, and in places near the fault it contains layers of fibrous carbonate of lime, like th e "Beef" of tIle Purbeck Beds, No Fuller's Earth of commercial value is known to occur in th e beds in thi s district. Delicate bivalves of the genera Lucina, jV?/aeiles, N ucula , &c., are met with in th e marl , of which about 90 feet is her e shown. Dr. \Vright notes also Ostrea acuminata and Terebratula ornitho­ cephala ;" The upper part of the cliff is formed of Forest Marble, exhibiting a mass of shell-limestones 10 or 12 feet in thickness, overlaid by 30 feet of clays and shnly limestone and thin tlaggy limest ones, and underla id by similar clays, thin limestones, and shuly beds (here about 50 feet in th ickn ess). At the base of these lower clays is a hard brown sandy marl , one foot or more in thi ck­ ness, contai ning many specimens of Rh yne/tOnelia (R . B oucti and R. varians) , rValdheimia diq ona, W. obora ta, Terebratula maoiil­ lata, &c. The writer has noticed th e same bed east of Burton Brudstock, and at Herbyleigh, near W eymouth. It appears to represent the Bra dford Clay. At Eype a conspicuous band of hard pale marl occurs below thi s bed, marking th e junction with Fuller's Earth. The mist which shrouded the hill-tops quite obscured the view of th e fault at th e west end of the cliff. Here, however, the beds of Forest Marbl e and Fuller's Earth have been dragged upwards against th e fault j in the same way tho latter formation has been shifted against the sands to th e east. Th e Middle Lia s here consists of sands with indurated bands and concretions (much lik e the Inferior Oolite Sands) , resting on laminated clays and sands with impersistent beds of Baggy mica­ ceous sandstone, and the se again rest on blue marly clays with Ammonites marqaritatue. On top of these blue clays is a thick interrupted band of hard calcareous sands tones, kn own as th e Star-

'" 'Quart. J ouru, Geol, Soc. ,' Vol, xii, p. 310. See als o Damon, . Geology of Weymouth,' &c., 1884, p . 223. 208 EXCURSION TO BRIDPORT, BOTRENHAMPTON, ETC. fish Bed. Blocks of this bed may be seen on the beach, among the debris of Fuller's Earth and Forest Marble. Further westwards, towards Seatown, they are much more abundant, and the former occurrence of the Starfishes Ophius-a Eqertoni and O. tenuibra­ chiata is evident from the carefully chiselled-out hollows which may be generally seen on the smooth surfaces of the blocks. '*' A conveyance awaited the members near Eype's Mouth, and after a pleasant drive through narrow lanes, the town of Bridport was again reached. The rarity of trees along the sea-coast had been noted; but the presence of some stunted Scotch firs, bent and twisted towards the north-east, spoke forcibly to the severity of the south-west winds, and to the struggle which trees had for existence in exposed situations. The deep sandy lanes of this district called forth some remarks. Here they are excavated in the sandy beds which form the upper part of the Middle Lias, sometimes to a depth of 15 or 20 feet. One particularly fine example of a deep lane is to be seen on the north-west side of Colmer's Hill. Similar lanes are frequent also over the area of the Inferior Oolite Sands near Bridport and Beaminster, in Dorsetshire, as well as near Yeovil, in Somerset­ shire. During a visit which the writer paid lately to the districts in company with the Director General of the Geological Survey, Mr. Geikie pointed out that these deep lanes were evidently formed to a very large extent by ordinary denuding agents operating on a surface kept constantly bare by traffic. The absence of any signs of "tipped" material on either side of the lanes was opposed to the view of their excavation by man. The fact that the crests of the hills were not deepened, proved that the excavations had not been made to improve the gradient of the roads, nor for the purpose of concealing them in old times. On the other hand, in wet weather these roads are the beds of temporary streams, and considerable denudation must take place. Indeed, granted an original track-way, it seems simply a matter of time, perhaps of centuries, to produce by natural agencies, aided no doubt by traffic, the curious and picturesque lanes which abound in the softer strata of this district. Mr. Hudleston remarked on the similar character of many lanes

• For an excellent account of the Middle and Upper Lias of Dorsetahire, see paper by E. C. H. Day, • Quart. J ourn, Geol. Soc., Vol. xix, p. 278. E XCURSION TO BRIDPORT, BOTH ENHAMPTON, ET C. 209 in the Old Red Sandstone of Herefordsbire, the deepening of which he had no doubt was largely due to natural causes.* During the course of the day the party became reduced, as some members desired to leave Bridport by an afternoon train. Some again parted at the Bull Hotel, Bridport. In th e evening a faithful band of nine dined with the two Directors at the Mermaid Hotel, Yeovil, after which they went, each to his separate destination.

EXCURSION TO READING.

SATURDAY, JUNE 6TH, 1885.

D irectors : -I, H. BLAKE, F.G.S., Assoc.wLlnst.C.E., of the Geological Survey; and Dr. JOSEPH STEVENS, Hon. Curator of the Reading Museum. (Repol1 by THE Dmncroas.) Notwithstanding the unfavourable state of th e weather, between thirty and forty took part in this excursion. The Members from London were met at th e railway-station at Reading at about 11.15 a.m, by th e Director s, and were shortly afterwards joined by some members of the Henl ey Field Club. and also by a few be­ longing to other local societies. The assembled excursionists , crossed the Th ames by th e road­ bridgeand proceeded to th e top of St .P eter's Hill. Cnversham , where the Chalk is overlaid by implementiferous gr avel. Here, in a pit on th e east side of the W alling ford Road, a clean-cut section down to the Chalk showed the grav el to be six feet in thickness. Dr. Stevens exhibited a few specimens from his lar ge collection of paleeolithic flint-implements obtained from th e gravel in this locality , the surface of which is about 119 feet above the level of the Thames, and 234t feet above sea-level, He stated that the palreolithic implements differed in some respects from those found at Grovelands, on the opposite side of the valley, where th e grav el was at a lower level. Those from Grovelands were mostly oval or oval-pointed; whereas here they were chiefly acutely-pointed or spear-shaped, but occasionally oval ones were found. No animal

* This explanation of deep hollow lanes in sandy strata has been given by Gilbert White, ' Nat. Hist. of Selborn e,' Letter v, 1789; and W. Topley, , Geology of the Weald ' (M om, Geol. Surv ey), p. 380, 381 j VOL. [X., No.4. 16