434 EXCURSION TO ALDEBURGH, WESTLETON, AND DUNWICH. WHITSUNTIDE, MAY 29TH TO JUNE 1ST, 1898. Directors: W. WHITAKER, F.R.S., PRES. G.S.; F. W. HARMER, F.GS.; AND E. P. RIDLEY, F.G.S. Excursion Secretary: BEDFORD McNEILL, A.R.S.M., F.G.S. (Report by F. W. HARMER.) THE members left Liverpool Street Station on Saturday. May 29th, by the 11,45 a.m. train for Aldeburgh. On arrival, they proceeded to the Brudenell Arms Hotel, the head quarters. A short excursion was made during the afternoon to the hamlet of Slaughden, half a mile south of Aldeburgh, to inspect the damage caused by the high tide of November, 1897. It will be seen by reference to the map (Fig. 1) which, with other illustrations, has been reprinted from a paper by the writer," by the kind permission of the Council of the Geological Society, that the river AIde approaches Slaughden at right angles to the coast, and the estuary, of which the present stream is the shrunken representative, must formerly have communicated with the sea in that direction. The travel of the beach, which on the eastern coast of England is from north to south, that is, in the direction of the currents attending the flowingtide, caused, however, the accumulation of a bank of shingle across the mouth of the estuary, and this bank continuing to increase in the same direction, gradually shifted the outfall to the south. At present the river AIde enters the sea at a place called Shingle Street, 8 or 9 miles from Aldeburgh, running parallel to the coast between the two places, a narrow belt of shingle-beach and salt marsh only intervening. The high tide referred to transferred great quantities of shingle from the seaward to the landward side of the bank, rolling the pebbles over its crest, shifting the position of the bank westward, and causing it to make in places great inroads on the adjoining marshes. A number of buildings that stood im mediately behind the bank were wrecked or damaged by its advance. It is a hundred years since the poet Crabbe, then Rector of Aldeburgh, prophesied such a calamity in the following lines, appropriately quoted by Mr. Monckton from" The Village" : Till some fierce tide, with more imperious sway, Sweeps the low hut, and all it holds, away. One of the principal objects of the excursion to the Aldeburgh district was an examination of the zone-theory of the late Sir • Quart. ] ourn. Geoi, Soc., vol. !iv, p. 308, 1898. NOVEMBER, 1898.] EXCURSION TO ALDEBURGH, WESTLETON, AND DUNWICH. 435
S~alt' (1/ .1/ila o \,
M ~ p of the main mass of the CORALLINE CRAG; ! hcwing t he posltlon of the .... arlous sections and borii\.1) alluded to In t his paper. T /;( c/oflrd a rra ""p,..-sm!s f,~ a ! c.r.·..·r~·J t')' t/:e C"r.:tlillc C,."g'. -,
FIG. I. NOTE.-The posItIon of pit 30 should have been indicated just below the letter K (in "Kiln") due west of Aldeburgh. (Reprinted by permissio» Iron» The Quarterly Journal of the Geological Socieiy.) 436 EXCURSION TO ALDEBURGH, WESTLETON, AND DUNWICH.
Joseph Prestwich, the correctness of which has recently been challenged by the writer." It has been held by all authorities to the present time that the Coralline Crag may be divided into a lower portion, composed of whitish, incoherent, calcareous sands, with frequent beds of shells, and an upper bed of indurated ferruginous rock. Prestwich adopted these divisions, but he believed that the lower part of the formation might further be separated into five distinct and continuous zones, representing great physiographical changes, induding a gradual submergence of the Crag area to a depth of 500 or possibly of 1,000 feet, and alternations of climate by which at one stage the winter tempera ture of Northern Europe became sufficiently cold to bring floating ice from Scandinavia or the Ardennes to the shores of England. The writer has given in the paper already referred to the reasons which induce him to differ from these views. So far from admit ting that the Coralline Crag can be divided into a number of zones, he now believes that the distinction between the shelly sands of Gedgrave and Sudbourne, and the ferruginous rock of Iken and Aldeburgh, is more apparent than real, and that the one is merely an altered condition of the other. With the exception of that of the basement bed, the material of the Coralline Crag is practically identical throughout, being almost entirely organic, formed of the comminuted remains of polyzoa and mollusca, with seams of perfect specimens of such organisms, and it must all, therefore, have originated under similar conditions; probably as a bank, in water of no great depth, parallel to the western shore of the Crag sea, and at no great distance from it. The molluscan remains are, with very few exceptions, the drifted shells of dead animals only, differing in this respect from the contemporaneous Isocardia-beds of Antwerp, which represent an undisturbed sea-bottom, the lamellibranchiate fossils of those beds being always found double, and never arranged in layers as in the Crag. It seems probable that the Coralline Crag banks were due to currents from the south-west flowing through a strait that connected the North Sea with the English Channel, which deposited little sediment where they ran strongly, but swept up from the sea-bottom the shells of mollusca living on it, depositing them afterwards in comparatively sheltered situations where the influence of the current was less felt.j Similar conditions now obtain off the coast of Antrim and at the southern end of the Isle of Man. An interesting proof of the identity of the two kinds of Coralline Crag was pointed out in pit No. 27, at the Brick Kiln Farm at Iken, visited on the 30th (see Map, p. 435), where a lenticular patch of the deposit in its unaltered condition, crowded with perfect shells like those of the sands at Gedgrave and elsewhere, occurs in the midst of a mass of the indurated * Oua rt./ourn. Geol. Soc., vol. liv, p, ~oB. 1898. t the writer's views as to the geographical conditions under which the Coralline Crag. may hav e originated are shown in th e accompanying map (Fig. •). e-, ,.,ll'j <""l ':'I."I'~',, : "'!" Sleeuretl Rocks .\J.h..{.ur.:h ,
~ ", • · 1 , I Jk t"u.
m flH" i ~u.l)l t o L_.., ...... l"lIlt~ OlI' 1·atlillJ:"On ~ c(' ~z ::>c Q Z -t,
Z~ 0 E-< (zl
~~~~:'<, ...l ------._-----;- ~ -.-"-'"-",, "', E- ~c ial (Reprinted by pen/liss;on from The Quarte rlf f aurna i of ti,e Geolo. S ociety .) 438 EXCURSION TO ALDEBURGH, WESTLETON, AND DUNWICIJ. ferruginous rock bed. Visitors to this spot are particularly requested to leave untouched this interesting patch of Crag, probably the only one of the kind in existence. The shells included in it can easily be obtained near Orford, and in a better state of preservation. In other places, as at pits 31 and 33 at Aldeburgh, visited subsequently, layers of molluscan fossils are to be observed, but in the form of casts only, the calcareous matter of the shells having been removed by the infiltration of acidulated water, which has at the same time dissolved a portion of the glauconite usually present in the shelly sands, and produced the ferruginous and indurated condition of the altered Crag. In pit No. 24, seams, a few inches in thickness, of reef-build ing polyzoa were noticed, extending horizontally across the section. It is suggested that these seams, which occur in places only, were due to the temporary diversion of currents, by which the accumulation of comminuted material ceased for a time at certain spots, so that polyzoa could there establish themselves, but they would afterwards be smothered and unable to exist when the returning currents brought over them again a new layer of the fine calcareous mud. At pit 25, now obscure, the position of the overlying Red Crag was pointed out, and at the disused brick-field, 26, a patch of Chillesford Clay was observed at one part of the section. MOllday, May 3Ist, was devoted to the examination of the exposures near Aldeburgh . Commencing the day's excursion at the pumping-station of the Water Works Co., where the arrange ments for supplying the town with water were explained, the party visited successively pits 30, 34, 31, and 33, where a number of specimens of polyzoa, some echinoderms, and many casts of mollusca were obtained. Mr. P. F. Kendall pointed out many years ago * that the preservation of the polyzoa, and of a few mollusca such as Pecten, Mytilus, and Terebratuia, in the indurated Crag was due to the fact that the shells of such organisms are composed of carbonate of lime in the form of calcite; aragonite, of which the tests of most mollusca consist, being more readily acted on by water containing carbonic acid. At the Aldeburgh 'brick-pit, where the section was photo graphed, a fine exposure of the laminated clays of the Chilles ford Beds was seen. It was pointed out that the most characteristic feature of these estuarine deposits is the constant and abundant presence in them of mica, derived, probably, from the Devonian and Carboniferous schists of Belgium, indicating that the Chillesford Clay estuary, like that of the Forest Bed of the Norfolk Coast at a subsequent period, formed one of the channels by which the Rhine and its afftuents then reached the sea. • Aragonite shells in the Cor. Crag. , Geo], Ma tr., Nov., , 883, p. 497. ..,.<"'l'" :Ii N.N.E. o s.s.w. ~ ~ Z ; ::;, ~ ~ .:i ..; .n G "'-' o ~ ~ ... " ~u ~ o " ... ~ j ." eo: U '"... ;; Lt Z > ":; ~.g ~ - - < «: :-. r: ~ c .§ ~.!i .D ..: t/. ~ g 2 - " z~ :-. ." -c ~ ] ; s 2 ·~-rl ""> -o .9- -~ ~ :;: o Vi ~ Q - tiS r:.:::=:: C2 iii t1 I 00 30 ~). ..uu ••••• • • h • • SEA i~ / __ .C 8 :- -- Tl! N D po; ~ o N ::;, c L Ii {tJ f ""'ii'jilL~4i ~ E' o N 9 c .A i' «: ~o o !-< § FIG . 3.-SECTI ON SHOW ING T H E STRUCTURE OF 'fUE C ORALLINE CRAG (ACCORDING TO THE PRESENT WR IT ER) AND T HF. PRO GRE S, IVE DIP TO THE N.N .E. OFITS JU NCTIO N WITH THE LONDON CLA Y. ~ T he thick straight bars indicate the position of the seams of large shells. Th e more recent beds arc omitted. ::> = o :< (Reprinted by permission fro m T he Qllar/eTly foum n; 0/ the Geological Societ)'.) ~ 440 EXCURSION TO ALDEBURGH, WESTLETON, AND DUNWICH. The section (Fig. 3) shows the structure of the Coralline Crag according to the writer's views. From borings recently made by him, which are shown in the section by vertical lines, it appears that the formation dips regularly to the north between Gedgrave and Sudbourne, as it does from Sutton to Gedgrave. It is about 60 feet in total thickness at Sudbourne Park, where the unaltered shelly sands and the upper ferruginous rock bed are both exposed. At Aldeburgh and Iken the rock bed only is visible. A pleasant interlude to the more serious business of the day was a visit to the garden of the hospitable Chairman of the Aldeburgh Water Works Co., Mr. [as, Flintham, where refresh ments were kindly provided, a compliment which was happily acknowledged by Mr. E. T. Newton in an appropriate speech. The day's excursion was brought to a close by a visit to the ancient Town Hall, a quaint and interesting building of the Tudor period, where some old maps of Aldeburgh are preserved. The pit of Norwich Crag formerly existing near the Gas Works is, unfortunately, no longer accessible. After dinner, on the motion of Mr. E. T. Newton, votes of thanks to the Directors and to Col. S. W. Smythe and Mr. Joseph Flintham were passed with much enthusiasm. Tuesday, June IS!, carriages were provided to take the party to Westleton and Dunwich. The route led over the higher ground, covered with the Middle Glacial Sands and the overlying Chalky Boulder Clay; but as, unfortunately, rain fell during this part of the journey, no opportunity of examining these deposits could be found. Soon after reaching Westleton, the weather improved, and a visit was paid to the famous gravel pits on the Heath, first described by Prestwich. The beds there shown are composed almost wholly of flint, as is the shingle beach of Slaughden, but they contain also an insignificant percentage of small pebbles of quartz, jasper, and lydian stone. These gravels may be traced to the cliff at Dunwich, where they rest on the Crag sands, and, in the writer's opinion, to Henham, Halesworth, Southwold, and still further to the north. Mr. A. E. Salter, who has paid much attention to the subject, observed, however, that in his opinion some at least of the Southwold gravels are of different age. According to Prestwich, the Westleton Beds agree lithologically with the gravels which fringe the northern side of the Thames Basin, the latter being probably drifts arranged round the various gaps in the high ground of the district. Mr. H. B. Woodward observed that no fossils, belong ing to the formation, had ever been found in the Westleton Shingle of Westleton, and he regarded the deposit as forming part of the" Middle Glacial" beds of East Aflglia.* * See Geol, Ma.r;., r88., p, 455, and r896, p. 357. The specimens referred to by Prestwich, Quart./ourn. Geot, Soc., vol. xlvi, p. 96 (footnote), were in my opinion procured from the Norwich Crag beneath the Westleton Shmgle.-H. B. W. EXCURSION TO ALDEBURGH, WESTLETON, AND DUNWICH. 441 At Dunwich the party was met by Mr. Ed. Lingwood of that place, whose picture in this year's Academy has been much admired, both from an artistic and a geological point of view. Guided by him, a short cut was taken across some fields to the cliff, where an unusually good section presented itself, thanks to the high tide of last autumn. The Westleton Beds are shown cutting into" the unfossiliferous sands of the Crag," here decalci- Feet 3 .. .a ) r I a. Surfa ce soil, gravelly. 21 ~ b. Fine shingle, with len ticular beds of white [' sand. ), c. White sand. i d. Light greenish clay. ~ c ) e. White sand, passing down ...tI into ochreous pebbly ) sands, with a few large "( .. unworn blocks of flint and some ironstone bands and concretions. 1 1 C ~ I ~ FIG. 4.-GENERAL S ECTION OF T H E WESTLETON BEDS, WESTL ETON COMMON.- Prestwich. (Reprinted by permission [rom.T he Quartetly J ournal 01 the Geologi cal Society.) fled by infiltration, and for the most part stained a bright orange colour. The lower part of the Crag, in an unaltered condition and full of fossils, is now well exposed at the base of the cliff, and it is to be hoped that collectors will not lose the opportunity of adding to the list of mollusca from this part of the Norwich Crag series. After lunch, many of the members visited Mr. Lingwood's studio, and inspected his collection of coins and a varied ,j>, South . :'\"n h. ,j>, t-) ;'II i nsmcre Level. t, ~ ;:';~;~SY~ ~ I . (5 ~~':~~:'~ ~~~~ :~;~ ~ L ,._Jo Z C5 T aIus at foot of cliff, r> Sout h. ti Xorrh. t, ~~ ,;'~ - -.._,"" ... "~' .....'""'-.:----.." .: / "/-:" ":; . , ~ e t, assortment of articles found on Dunwich beach, and many other objects of interest. A discussion ensued between Mr. Whitaker and the writer as to the relation of the Norwich Crag of Dunwich to the Red Crag, the former gentleman being disposed to regard the two deposits as more or less contemporaneous. In opposition to thi s view, it was urged that whereas the different stages of the Red Crag are characterised by a gradual disappearance of many of the extinct and southern species present at Walton-on-the Naze, the oldest part of that formation, a number of them linger ing on until the latest or Butley stage, that these forms had, with but few exceptions, disappeared altogether from the North Sea before the deposition of the Norwich Crag. The fauna of the latter presents a more decidedly modern and more boreal facies than does that of the Red Crag, and its characteristic species are fewer in number. The Norwich Crag beds contain, moreover, abundantly one arctic form, Astarte borealis, which has never been found in the Red Crag, and another, Te!lina lata, which is exceedingly rare in the lalt er formation. At Southwold, only four miles from Dunwich, a boring showed that the Crag extends to a depth of more than 100 feet below the sea level, and that it has a total thickness of 147 feet. The fossils obtained from this boring were all distinctly of the Norwi ch Crag type, and there is no evidence, either at Southwold or elsewhere in the district, tha t beds of Red Crag und erlie those of Norwich Crag age. The latter, however, belon g to the same set of conditions as the former, marking merely a more recent stage of the newer Pliocene period. In the writer's opinion the beds of the Upper Crag are arranged for the most part in horizontal rather than in vertical sequence, and are the marginal accumulation of a sea gradually retreating north wards, in consequenc e of the earth movements trac ed out in his paper on the Pliocene depo sits of Holland.* A walk along the beach towards the inn showed, inter alia, the remains of an old well, a relic of the once important town of Dunwich, and a small patch of almo st decalcified Chalky Boulder Clay. After lunch at the Barne Arms, carriages were again in requ est, and Darsham Station was reached in good time for the train for London, bringing only too quickly to a close an exceed ingly pleasant and successful excursion. R EFER ENCES. Geological Survey Map, Sheets 49 N., I S. 6d. ; 49 S., IS. 6d.; 50 N.E., 35. ;. 50 S.E., 35. Ordnance Survey Maps, New Serles, Sheets 191- 208, IS . each. 1871. PRESTW ICH, JO SEPH-" On the Crag Beds " (3 papers). Qua,·t. J ourn . Geol. Soc., vol. xxvii, pp. I1S. 325, and 453. • Quart.Joiox, Ceor. Iii, p. 748, r8 ,6. 444 PROCEEDINGS. 1872. WOOD, S V.,jun., and HARMER, F. W.-" An Outline of the Geology of the Upper Tertiaries of East Anglia." Pal. Soc. Supp. to the Mon. of the Crag Mollusca, etc. TAYLOR, J. E.-" Excursion to the Crag District of Suffolk." Record of Excursions, p. 187. 1885. WHITAKER, W.-" Geology of Ipswich," etc. Mem, Ceo!. Survey. Pricev cs. 1886. DALTON, W. H., and W. VVHITAKER-" Geology of Aldborough," etc. Mem. Ceo!. Survey. Price, IS. 1887. WHITAKER, W.-" Geology of Southwold, and of the Suffolk Coast." Mem. Geol, Survey. Price, zs. 6d. 1887. ------"Geology of Halesworth," etc. Mem. Ceo!. Survey, Price, IS. 1890 • PRESTWICH, JOSEPH-I< On the relation of the Westleton Beds," etc. Quart. J'ourn. Geol, Soc., vol. xlvi, p. 84. 1890. REID, C.-I< Pliocene Deposits of Britain." Mem. Geol. Survey. Price, 5s. 6d. 1896. HARMER, F. W.-" Pliocene Deposits of Holland, and their relation to the English and Belgian Crags." Quart. J'ourn. Geol. Soc.; vol. Iii, P: 748. 1896. SALTER, A. E.-" Pebbly Gravels from Goring Gap to the Norfolk Coast." PrOG. Geol, Assoc., vol. xiv, p. 389. 1898. HARMER, F. W.-" Pliocene Deposits of the East of England. The Lenham Beds, and the Coralline Crag." Quart. J'ourn. Geoi. Soc., vol. liv, p. 308. 1898. SALTER, A. E.-" Pebbly and other Gravels in Southern England." Proc. Geoi, Association, vol, xv, P: 264. ORDINARY MEETING. FRIDAY, MAY 6TH, 1898. J. J. H. TEALL, M.A., F.R.S., President, in the Chair. Miss G. E. Robinson, John W. Grime, and Thomas Draper were elected members of the Association. A paper was read by Mr. Horace B. Woodward, F.R.S., F G.S., entitled" Notes on Skye," and was illustrated by lantern slides, maps, and specimens. Mr. A. Strahan, M.A, F.G.S., then gave a lucid account of his observations in Lapland, dealing more especially with the Raised Beaches and with the glacial phenomena of Palseozoic and Pleistocene age in the Varanger Fjord. His remarks were illus trated by lantern slides. ORDINARY MEETING. FRIDAY, JUNE 3RD, 1898. J. J. H. TEALL, M.A., F.R.S., President, in the Chair. The following were elected members of the Association:- D. A. Louis, Miss Mary S. Johnston, Malcolm Poignand, M.D., and Martin A. C. Hinton. A paper was read by Mr. A. Smith Woodward, F.L.S., F.G.S., on "Fossil Sharks and Skates, with special Reference to those of the Eocene Period."