A Contribution to the Geological History of Suffolk (Part 2)

A CONTRIBUTION TO THE GEOLOGICAL HISTORY OF SUFFOLK Part 2 THE

GEOLOGICAL

HISTORY OF THE SYSTEM.

HAROLD E . P .

SPENCER,

ORWELL-GIPPING

F.G.S.

ALL evidence of the pre-Pleistocene geography and topography of the East Anglian region of the pre-Red Crag epochs has been destroyed by early glaciations and the incursion of the Red Crag Sea, of which a remnant of the pebbly beach deposit, about eleven feet thick and situated 150 feet above the present sea level, is preserved at Battisford, (GR 061538). From well borings west of that parish, some of which appear to have over one hundred feet of Crag Sands, there seems to have been an island here in the Crag Sea. Fossils of land faunas of earlier epochs prove the existence of former Continental stages, each of which was destroyed by subsequent marine incursions during the history of the region.

The late Professor P. G. H. Boswell recorded an abnormal thickness of Red Crag Sand at Woodbridge waterworks which may represent a pre-Red Crag Valley. The low base level of the Norwich Crag at Southwold (minus 170 feet), indicates a greater land area in an earlier period when the climate was probably extremely cold. The buried Channel at Ipswich was fjrmed at a later period.

The Gipping is a modest system consisting of a number of small streams draining the boulder clay uplands, just over 250 feet high, of eastern mid-Suffolk from Bacton in the north, Mendlesham in the east and Felsham in the west. Such streams are frequently dry during the summers. The name is generally supposed to be taken from its source in the Parish of Gipping, the fact is that the eastern stream only crosses the border for a short distance whereas the major branch flows from the west.

It is therefore considered possible the name Gipping commemorates the Anglo-Saxon settler Gippe. His settlement became mediaeval Gippeswyk, now corrupted into Ipswich.

A series of streams from Wetherden in the north, Felsham in the west (rising near Noah's Ark Farm) and the Finborough region in the south, having converged, join the Gipping immediately south-east of Stowmarket. The water from these tributaries unquestionably forms the major part of the system. A small stream rising just west of Battisford Tye and flowing via Coombs is one of a few which flow from south to north.

GEOLOGICAL

HISTORY

291

In this account of the area it is proposed to describe the geology from Stowmarket to the sea so far as commercial excavations and temporary sections have permitted observations to be made.

In Part 1 all the deposits have been described in their natural order and to avoid repetition it is hoped readers will refer thereto if necessary.

Only the two tills, Lowestoft and Gipping, occur in the upper reaches together with glacial sands and gravels in places. In one temporary excavation both tills were seen one above the other; the Gipping is normally uppermost except where it has been eroded.

Stowmarket Stowmarket brickworks apparently utilised Lowestoft Till and the site is now a market garden. East of the Station there are thick deposits of sand some of which may be part of the Crag series, or perhaps redeposited Crag sand. The pit on the east side of Old Newton Road (GR 502594) has produced botryoidal (grape-like) concretions unlike anything from other East Suffolk sands.

There are few geological sections in the upper reaches and only glacial tills (boulder Clays and outwash gravels have been exposed).

The former economic use of the tili was for "Wattie and Daub" for timber framed houses and "Clay lump" for cottages and farm buildings. Both required a coating of lime mortar prepared from chalk for protection against the weather.

Downstream to Needham Market the Gipping flows through low lying ground, some of which is marshland. Gravel occurs on the valley slopes but there has been no opportunity to ascertain its character.

Battisford A stream from Ringshall flows via Battisford and Badley to its confluence with the Gipping just north of Needham Market.

Near Valley Farm a pit was worked in the Red Crag Pebble Beach deposit where it rests on Chalk (GR 058535) at the 150 feet contour. Another exposure is on the west side of the Hascott Hill valley (GR 061538) where the pebble bed has been exposed to eleven feet. At the top of the bed impressions and casts of mollusca are poorly preserved but lower down near the water table shells occur between the stones some of which retain encrusting species of polyzoa. Shark's teeth and fragments of cetacean bone such as are found in the Crag Basement Bed sparsely occur.

292 Transactions of the Suffolk Naturalists',

Vol. 13, Part 5

T h e deposit is buried below glacial sand and Lowestoft Till.

A well in the village penetrated ninety-five feet of glacial drift and about 100 feet of grey and green Crag Sands. Incidentally the Crag is not normally red, the colour being due to the oxidation of iron Compounds by percolating water. In places the Crag is white owing to the absence of Glauconite in the original deposit; this mineral is a hydrous Silicate of iron and potassium.

N e e d h a m Market—Creeting St. Mary Commercial exploitation of chalk, gravel, and sand has revealed much of the geological history of the valley. A spur of tili capped chalk extends eastward from Barking and the chalk is quarried for agricultural purposes by Needham Chalks Ltd. ( G R 093541) from whom permission to visit must be obtained.

On the left bank at Creeting St. Mary, Broomhill (GR 09553 to 560) is riddled with excavations and can have few more secrets to reveal. T h e surface of the chalk has been denuded to about fifty feet and on it is a layer of flints, etc., resembling the Basement Bed of the Red Crag. Above this is some twenty feet of white sand rieh in small flakes of mica. Extremely rare internal casts of marine mollusca, such as Turritella occur proving its marine origin. This sand is beautifully current bedded and is slightly iron stained toward the top and there is a scatter of flints and non-flint silieeous sub-angular stones in the upper part where the deposit is thickest. This greyish sandy gravel occurs also at Bramford above the Red Crag sands. Exposed sections of the white sand are sculptured by wind which reveal a number of minor faults probably due to the v/eight of ice during a glaciation. This sand has been traced via Rushmere to Tuddenham and Hollesley where it lies on Red Crag. At Valley Farm, Sproughton (GR 115434) near Washbrook, the bedding passes down into the shelly Red Crag just above the watertable.

Formerly a thin Stratum of laminated clay, presumably that recorded in the first Ipswich Memoir of the Geological Survey as Chillesford Clay, is probably an outlier of the similar clay in Easton Bavent Cliff. The Baventian Clay has been proved by Dr. R. G. West from the pollen analysis to have been deposited in a cold sea towards the close of the Norwich Crag marine epoch.

T h e white sand has not hitherto been recorded in geological literature and the evidence so far implies it is part of the Crag Series. T h e laminated Baventian Clay at Creeting has now been destroyed together with about four feet of Lowestoft Till which rested on it (see FIG. 6).

Above the white sand, etc., is fifteen to twenty feet of current bedded outwash gravels of Gipping age which are interesting by reason of the quantity of derived Crag shell fragments contained therein, also of polyzoa from the Coralline Crag. T h e latter

GEOLOGICAL

HISTORY

293

implies there were Pliocene deposits to the north of vvhich no other evidence is known. Gipping gravels at Sproughton and Haugh Lane, Woodbridge similarly contain Crag debris. These gravels have been largely removed west of the lane along the hilltop and their relationship to the overlying Gipping tili is proved by the erratic rocks from both deposits which are similar.

T h e erratics (ice transported rocks, etc.) are important in unfossiliferous deposits in the determination of the relationship of glacial beds and together with the preferred orientation of the longer axes of the stones, indicate the direction from which the ice originated. Lowestoft ice conveyed rocks from the west side of the Pennines, the midland piain and the Isle of Ely where it picked up a quantity of Kimmeridge Clay which gives the tili its characteristic bluish slate colour. Gipping Till is usually greyish to buff in colour and contains rocks from Lowland Scotland, the Cheviots, Yorkshire, and Lincolnshire. Locally it may be excessively stony or chalky. A large boulder, four feet in diameter, could formerly be seen in a worked out pit at Creeting but it has since been buried; a similar eight feet boulder of Spilsby sandstone at Stone Farm, Blaxhall will presumably record the former eastward extent of Gipping ice for many years.

Coddenham A small stream from Ashbocking draining the boulder clay plateau and flowing via Hemingstone has cut down into the chalk at Coddenham joining the Gipping south of Bosmere Hall.

T h e lower part of this Valley has had all post Cretaceous beds eroded and a shallow quarry in the chalk is worked in the village (GR 132453). There is a small abandoned quarry beside the A140 at the north end of Shrubland Park Long Covert below an artificial mound (Beacon Hill), the surface of which is littered with flint artifacts, etc. There is a chalk exposure beside the road close by (GR 110543).

Gallows Hill Behind the garage a gravel pit formerly exhibited the folding of strata, a phenomenon typical of ice pressure on soft rocks past which it flows. T h e r e is now no evidence to show which glaciation was the cause of the disturbance.

Darmsden On the edge of the plateau above Gallows Hill a shallow gravel pit was made on the site of a Roman cemetery (GR 100532). T o the south of the Chapel a larger pit (GR 095525) destroyea the site of an Early Iron Age village dating from 400 B.C. which became Romanised and lasted to the fourth Century A.D. Part of the gravel consisted of alternating beds of pebbles and more

294 Transactions of the Suffolk Naturalist?,

Vol. 13, Part 5

normal gravel. The pebbles were probably derived from the destruction of part of the Red Crag beach deposits, remnants of which exist at Battisford. In the western part of the working Calcrete (sand or gravel concretions formed by the redeposition of Calcium carbonate from the Solution of chalk in overlying tili), exhibitiing unusual flow structure was observed. The circumstances of deposition of this gravel seem to have differed from the Gipping gravel at Creeting. The deposit is believed to rest on Lowestoft Till.

Baylham (GR 109521) Another Chalk spur, capped at its eastern end with a very coarse morainic gravel, (the small section is now obscured), causes a slight bend in the river near where the Roman Road from Colchester to Caister crossed it. Similar morainic gravels have been observed at the margins of glacial Channels at Ipswich.

Barham (GR 120515 and 109510) On the left bank between the site of Barham Workhouse and the river two firms work the Valley gravels. In Broomfield Pit to the north the floodplain gravel is now being worked below the marsh level. Formerly gravels to the south in slightly higher ground when worked proved to be complex, on the east and west of the area the gravels were mammaliferous and somewhat older than in the middle where patches of an admixture of chalky gravel (tili) suggest a Valley glacier of the last glaciation. This deposit was seen in places to be channelled with much coarser unbedded gravel of a later phase. Here the uppermost gravel consists of mainly frost shattered flints.

Eastall' s ^y the railway crossing is in a low knoll rising above the fifty foot contour consisting of current bedded sand and gravel with mammalian remains. The deposits are chalk free and have been worked to over twenty feet below the water table. Boulders of sandstone, limestone, igneous rocks, and occasionally garnetiferous schist from Scotland prove the gravel to be redeposited glacial outwash brought down by floodwater towards the end of last interglacial.

At, or near, the lower limit of excavation there is a grey silty Stratum of sand with seeds of aquatic plants and bones of Mammoth and Woolly Rhinoceros. There are also freshwater mollusca, of which a small species of Succinea sp.* are by far the most numerous, occurring in limited patches with small angular flints. Mammalian remains from this level are better preserved than those from the gravel above, the condition of which may indicate partial weathering before burial. Rhinoceros limb bones are often found to have been

*B. W . Sparks was unable to determine this species.

GEOLOGICAL HISTORY

295

gnawed by hyaenas which is supporting evidence for the weathering theory. Gnawed bones constitute the first evidence for the presence of hyaenas in Suffolk in post Crag deposits and the first fossil, an incomplete mandible with the carnassial tooth was eventually found by Mr. John Aldous of Haughley, to whose diligence many of the Barham fossils in Ipswich Museum are due.

He also gave a rhinoceros scapula and hyoid from the silt bed.

Fossil hyoids of mammals are of the greatest rarity and this specimen equals in size the same bone in our largest living species, the so called White Rhinoceros of Africa. Bones of the larger animals are more easily seen than those of smaller beasts and therefore are better represented in collections. Teeth of the Mammoth are common and representative of all age groups with a high proportion of juveniles; this is a feature common to all East Anglian mammaliferous deposits. Antler fragments of reindeer are fairly common but no bones have so far been found, but remains of a skull and antlers from a similar deposit at Bramford Road are in the Museum.

One pair of lower third molars of Parelephas trogontheri, are said to have come from above the water table and are so well preserved that they were probably protected by the much decayed mandible. Possibly the beam of an antler of a very large Red Deer, Cervus elaphus angulatus, with its bez tine, came from the same level representing different climatic conditions. This variety of deer has normally been found associated with a warm fauna at Brundon, Sudbury (GR 836417) and in the Stutton Brickearth (GR 14-33-), where the association of shells of Corbicula fluminalis and remains of the pond tortoise, Ernys orbicularis, now living no nearer than the R. Nile and southern Europe respectively, imply a warmer climate than we now enjoy. The shed base of a similarly large antler from the Hoxne Brickearth indicates angulatus also lived in Suffolk a quarter of a million years ago. Possibly the giant antler base from Kent's Hole named Strongyloceros spelaeus by Owen, circa 90 mm diameter* belongs to this variety of deer; incidentally "cave deer" seems a very inappropriate name.

Only a few bones and teeth of the small Barham race of horse are in the Museum but others are known to have had been taken by schoolboys who also took incomplete bones of the wild ox, Bos primigenius. There is one fine horn core of this species and sundry good portions of limb bones.

Remains of Reindeer, which have also been found at Bramford Road and in the Waveney Valley at Weybread, prove the low level deposits represent the deterioration of climate which heraided the last glaciation when the woolly elephant and rhinoceros became extinct in Britain. *Brit. Foss. Mammals (1846) p.469.

296 Transactions of the Suffolk Naturalists',

Vol. 13, Part 5

Fossils of large carnivors are not common but a few bones occur at many mammaliferous sites. Only one fossil is known from Barham, the lower end of a feline humerus. Remains of the larger cats have been generally referred to the so called "Cave Lion", Panthera (Felis) leo spelaea in the absence of diagnostic bones. The difficulty of determination is due to the very slight difference in the nasal bones and the inferior border of the mandible by means of which the lion can be distinguished from the tiger. If a mandible of lion is placed on a flat surface it will rock owing to the curvature of the inferior border of the bone, whereas the mandible of a tiger will stand firm. Tigers have a more northerly ränge than lions which within historic times ranged no further north than the Balkans, whereas the tiger ranges as far north as the Amur River (52°) in eastern Asia and up to the snow line in the Himalayas. Unfortunately feline jaw bones are all too rare and presumably many records of Cave Lion are based on arbitrary decisions of indeterminate bones. A mandible from the river terrace gravels at Brundon has proved that tigers were present in Suffolk during the last interglacial. It is interesting that a complete femur from Stutton, probably tiger, is half as long again as that of a modern lion and the Barham fragment of a humerus is a comparable size. The presence of wolf, Canis lupus, is proved only by an incomplete femur but it is known also from Brundon and recorded from the Stoke Hill Beds by Miss N. F. Layard early in the Century.

The Barham fauna, which is presumably duplicated in similar deposits of the Waveney Valley, includes:— Mammoth Woolly Rhinoceros Horse Wild Ox Reindeer Red Deer Tiger?

Hyaena Wolf

Mammuthus primigenius Parelephas trogontheri

common very rare*

Coelodonta tichorhinus Equus caballus Bos primigenius Rangifer tarandus Cervus elaphus angulatus cf Panthern (Felis) tigris Crocuta crocuta Canis lupus

very common not common common * very rare tooth marks common ?rare

The middle of the last interglacial is dated about 100,000 years B.C. while the late interglacial Barham Beds possibly date from about 25 to 30,000 years. At this time the river flowed at a lower level owing to the amount of water included in the expanding northern icecap having reduced the sea level.

The ancient trackway from Claydon Church through The Slade continuing past Barham Church to Sandy Lane, and once known as Chapel Lane, passes a small sand pit where many human " T h e s e two species probably represent a fauna of an earlier stage of the last interglacial.

GEOLOGICAL HISTORY

297

skeletons have been found. New Operations in the past few weeks have exposed the margin of a glacial Channel filled with Gipping Till of an unusual character. Normally this tili is a fairlv uniform sandy and chalky boulder clay varying from intensely stony to 90% chalk, but at Barham the tili is an odd mixture very sandy at the base, the ice having passed over mainly sandy gravel, with included pockets of ochreous sand and patches of flints.

T h e base of the tili slopes southward at about 30° at this site which is on the fifty feet contour. At the top of the S.W. section above the very sandy gravel, a section of a shallow Channel filled with very coarse gravel lies below a small patch of loess in a bed of exceptionally fine sand with tiny grains of chalk. Such deposits are usually associated with beds laid down underneath an ice sheet at East Suffolk sites.

Claydon A well dug at an unrecorded site in the Street yielded an incomplete humerus of an indeterminate rhinoceros. A recent excavation near the river bridge exposed the chalk at about ten feet proving the Ipswich buried Channel does not extend to that point.

Bramford T h e exposures above the chalk at the former noted Bramford (Coe's) Chalk Pit have no longer the admirable sections visited by many noted geologists because of the large scale removal of the gravels, neither is the chalk exploited. Boswell, in the 1927 Ipswich Survey Memoir, describes the deposits and a view of the pit is given on plate 1. T h e pit was worked by hand and the overburden removed in stages by small railways at each level.

It was here during the researches of J. Reid Moir that the first mammalian remains of Villafranchian deer were discovered in the Red Crag sand, but these were not recognised until twenty-five years later wlien they were recorded in these Transactions in 1963 (Vol. xii, p.261-6). Subsequent study of the fossils proves the following fauna were living during the Red Crag period:— Euctenoceros sedgwicki, E. falconeri, Dama nesti nesti, Ursus,

antler base of an immature deer. major part of antler related to the Fallow Deer part of tibia and fragment of canine tooth of an aged animal

Hystrix sp. (Porcupine) Cetacea, indeterminate, a vertebra

T h e presence of a tool using mammal related to man is indicated by an ovoid pebble discovered by the Abbe Brueil which bears striations from end to end obviously made by scraping with a flint tool, quite unlike abrasions, etc., caused by contact with other stones. This was preserved in the Ipswich Museum.

298 Transactions of the Suffolk Naturalists',

Vol. 13, Part 5

Here the sections were regarded as the most complete series in East Anglia consisting of Chalk; Thanet Bed, Reading Sand with clay pebbles; (London Clay missing); Red Crag sand with no shells but a typical Basement Bed; greyish gravel with a high proportion of non-flint siliceous erratics and vein quartz; Gipping gravel and Gipping Till. About a quarter mile south some twenty feet of London Clay was utilised for brickmaking. In the brickyard section the London Clay basal bed of slate coloured flint pebbles has now been shown to have been due to the destruction of the Oldhaven Sand of which a remnant was exposed at Hoghighland.

An excavation for the sewage disposal works near the former Station revealed a fine grained loess-like deposit below later river deposits. This is evidently the upper part of the buried Channel Alling, the existence of which was proved by a well boring at the Bypass Nurseries on the other side of the railway. T h e following sections were recorded:— 1.

at 2 4 ' 9" O . D .

Black soil Sand, chalk, and clay Loamy sand and bailast Firm black m u d Soft brown clay Gravel and sand Soft light grey clay (redeposited loess)

2.

1' 3' 4' w «r 15'

at 2 3 - 8 5 ' O . D .

Sand, ballast, and clay Coarse ballast and clay Sand and ballast Soft light grey clay

The Bypass Nurseries well boring log records:— 3.

at 4 0 ' O . D .

Yellow silty clay—?loess Sand and gravel Light grey clay (redeposited loess) Hard blue stony clay (?Lowestoft Till) Silt, sand, chalk, and clay Flint Blue clay Chalk rock

7' 5' 36' 53' 13' 1' 1' 1 1 6 ' t o chalk 64'

T o Chalk 116'

On the opposite side of Bramford Road is part of a chalk spur indicating the east side of the buried Channel must be almost vertical.

GEOLOGICAL

HISTORY

299

In a trench cut along Ship Lane in 1949, several portions of a very large antler of Caribou, the North American Reindeer, were discovered twelve feet below the road and nine feet above the river level. This unique specimen is comparable in size with the antlers of a very fine head in Ipswich Museum. Antlers of the Lapland Reindeer have usually been found below the vvater table well below the level in which the Caribou was discovered in dry loose sand below gravel. In the absence of other evidence no further comment can be made.

Great B l a k e n h a m (GR 105 to 110. 497 to 505) T h e extensive excavations for chalk and boulder clay at Great Blakenham for the manufacture of Portland Cement have revealed much evidence regarding the source of the ice which cut the buried Channel at Ipswich which there exceeds 130 feet in depth, but does not appear to extend downstream much below Cliff Quay.

This fact proves the "channel" to be a F I O R D E N and is not the result of a river cutting down to a lower level. This is confirmed by the nature of the beds in the channel which indicate it was a glacial lake during the retreat stage of the Lowestoft glaciation. Two borings at London Road, Ipswich penetrated to 110 feet without reaching the Chalk which is normally found at about nil feet O.D. locally. T h e lowest bed reached was thirty feet of Lowestoft Till succeeded by seventy feet of alternating beds of grey silty sand with abundant rounded chalk grains of an average thickness of one foot, and layers of buttery clay about two inches thick. T h e thick beds with chalk grains represent the summer melt and the thin clay layers a reduced volume of water in autumn or spring. At the top was river gravel containing Acheulean flint artifacts typical of the Great Interglacial.

This gravel is presumably the same as that seen in a trench section in 1938, between the lower and upper tills from which a horn core of bison was obtained, at Riverside Road, Ipswich (GR 14654525).

This F I O R D E N appears to have originated in a tongue of ice, in advance of the main Lowestoft ice front, following a preexisting Valley and ploughing down the vallev slope from the vicinity of the former College Farm (GR 110502) toward Claydon Hill where it was diverted southward. Evidence of ice pressure was recorded by Dr. George Slater at the old Claydon Chalk Pit in 1907 (GR 132495).

In the quarries of the Associated Portland Cement Company a number of interesting glacial phenomena have been observed as work progressed over many years. In the older clay pit the base of the Lowestoft Till has never been exposed and its thickness must exceed fifty feet. It is covered with Gipping Till and morainic gravel has been noted intervening at a few places.

300 Transactions of the Suffolk Naturalists',

Vol. 13, Part 5

Sections of Channels cut by melting water from the ice can be seen high on the south side of the older chalk quarry, these are filled with fine grey to ochreous sand. Parts of such Channels have been seen running between the tili and the chalk (see FIG. 7).

At the east end of the new chalk quarry, commenced in 1945, a section of a tili filled ice cut Channel of Gipping age can still be seen (FIG. 8). The vertical sides are partly indurated with calcium carbonate derived from dissolved chalk in the tili absorbed from melt water making the chalk as hard as marble. This hardening process has also proceeded below the tili while subglacial streams, sometimes torrential, were depositing fine sands and coarse gravel with well rounded stones. On the south side of the glacial Channel there are two curved hollows, small caves, which were originally sand filled but were cleared by rabbits (FIG. 8). On the right of the entrance to the old chalk quarry, below the tili representing the edge of the main glacial Channel, there is a large "lens" of sub-glacial sand. This is part of a stream deposit fiowing partly below and partly between the chalk wall and the Lowestoft ice, slightly to the east where the eastward dip of the chalk surface meets the road level another part of the deposit could be seen. At this point is the first exposure of the indurated chalk already mentioned; when the base of the tili, or more often the top of the sand or the sub-glacial gravel is hardened and the unconsolidated rock removed by water, wind erosion or by rabbits, a cavernous hollow is formed. To the left of the large lens in a former small side cutting two interesting sections of the south side of the main Channel were exposed.

That on the left face had a long streak of chalk in the tili parallel to the side of the Channel, on the right face was a fine sand with its thin bedding curved like the half section of an onion (see F I G S .

9 and 10). In the south-east section (old quarry) the edge of two parts of a sand filled Channel could be seen about half way down the chalk face at the "thrust plane" first mentioned by Dr. Slater, this indicates that melt water had made a passage through a considerable amount of chalk. [The Thrust Plane is an indication that the whole of the chalk above it has been displaced laterally by ice pressure.]

Above the chalk in the new quarry (begun about 1945), is a thick deposit of current bedded sands which appear to be outwash of the Lowestoft glaciation. This commercially valuable material has so far been dumped in various parts of the workings and may confuse future workers. Similar sand-filled small Channel sections occur high in the south face of the cutting between the quarries, and on the north side large pot holes were formerly exposed, formed by eddies in the sub-glacial torrent which deposited the coarse sub-glacial gravel, part of which has been cemented by redeposited lime forming a conglomerate.

GEOLOGICAL

HISTORY

301

Below the Lowestoft Till in the cutting to the new clay quarry sub-glacial gravel was exposed below what is now the road; at the west end of the excavation, however, fine richly ochreous sand only has beert observed.

In the south section there may still be seen (1966) remnants of buff coloured varved (laminated) clay which has been proved to be about twenty feet thick at Bramford Road (GR 133457) below Gipping Till. This type of deposit is attributed to the seasonal melt water from an ice front depositing the finest rock particles in a lake where the movement of the water is arrested.

(Similar deposits are produced today at gravel washing plants but the layers are due to each day's washing.)

This clay dates from post Lowestoft times but the colour is unlike varved clays which are known to result from the melting of Lowestoft ice, which are grey. Gipping Till is locally yellowish in parts owing to material included from the destruction of the laminated clay and it seems probable this deposit may be due to a retreat stage of the Gipping ice. The Gipping readvance was a major event which partly destroyed the clay at Great Blakenham (GR 506499). On the north side, now removed, there were curved shear planes in the tili clearly marked with yellowish traces of the clay. These being due to the subsequent pressure of Gipping ice, of which tili only a remnant remained on the plateau and this has largely been dug away.

Offton—Somersham Valley A stream from Gt. Bricett has cut down into the chalk which was formerly quarried at Offton and burnt for lime and this industry is commemorated by the Lime Burner's Arms Inn. This stream is generally dry but flooding occurs at Somersham.

The quarry at Little Blakenham has been reopened for agricultural chalk, here it is capped with glacial tili and gravel. At the present rate of progress Blood Hill, the site of a battle in Saxon times, will eventually be dug away (GR 112484). Lowestoft Till occurs on Chalk in the Valley bottom near Bramford.

Ipswich Reference to the presence of both tills in the Valley has been made and both have been exposed in trenches between the Norwich and Bramford Roads west of the railway. An isolated hummock of chalk exists a short distance west of Bramford Road railway bridge below which there is the Thanet Bed. To the south, across the river flood piain gravels have been exploited and the lower beds were proved to be mammaliferous: only Mammoth and Woolly Rhinoceros have been recorded.

302 Transactions of the Suffolk Naturalists', Vol. 13, Part 5 Bramford Road is an interesting area and possibly the best known in Ipswich. Opposite the Waveney Hotel mammalian remains of a fauna like that of Barham was pumped up during the extraction of gravel from thirty to forty feet below the road level.

Two portions of human limb bones presumably represent the people who produced the incredible number of flint artifacts of the Mousterian group of industries. The flints were variously patinated black, brown, yellow, and white indicating varying degrees of exposure before being buried, this implying changes in the topography during the last interglacial. Floods during the deterioration of climate towards the close of the interglacial drowned representatives of the fauna of this period and carried away earlier gravels which were redeposited with the bones downstream. An out-crop of Lowestoft Till at the northern end terminated the Operation.

On the Valley slope now behind the houses pale coloured sand below the Gipping Till was used for the manufacture of sand bricks. Subsequent trenching below the road exposed underneath a thin bed of tili (possibly slipped down from above), the top of a deposit of varved clay, similar to the remnants at Great Blakenham. Twenty feet of this bed was proved by boring without reaching the underlying Stratum, the lower laminae proved to be of increasing thickness and with a proportion of sand. When a large elm was blown down later its roots brought to light evidence of a hitherto unknown deposit of loess (wind borne dust not deposited in water).

Hadleigh—London Road The right bank of the Gipping-Orwell is generally less exposed than the left bank but some important data have been obtained from temporary excavations. (Incidentally the name Orwell is applied to the tidal estuary which extends to the London Road.)

The Hadleigh-London Road spur around which the river is deflected, was also an obstacle to the passage of the advance of the Gipping ice in its passage down the Valley. The results of ice pressure were revealed in the railway cutting across the end of this spur and the phenomena were closely studied by Dr. Geo. Slater in 1907, and 1915, in military trench systems. Here the strata have been overturned as by a giant plough as the ice exerted irresistible pressure while negotiating the bend in the Valley.

A typical example of the disturbed strata is shown in plate 1.

It has already been shown that the buried channel below this point was probably a glacial lake during the retreat stage of the Lowestoft glaciation because the Channel was undoubtedly ploughed out by ice of that period.

Gippeswyk Park The one inch geological map shows this area as London Clay but in fact the northern end is Gipping Till extending from

GEOLOGICAL HISTORY

303

below the railway to the oak wood (Waller's Grove). From the middle of the park a slight ridge runs southward marking the edge of the Red Crag and to the east of the ridge is all gravel.

In the trees of Waller's Grove a remnant of Lowestoft Till was observed tilted against an anticline of graded beds of chalky sand.

Each distinct bed from the bottom upward contained chalk grains from coarse below to fine at the top. To the south there was about four feet of Red Crag with much weathered septaria at its base.

Chantry Estate The numerous trenches exposed very thick gravels to twenty feet and in the upper part there were patches of white clay which may have been used by the Romans, if that is why they dug the pit which was found to be filled with fourth Century potsherds, etc.

The hillslope to Hawthorn Drive consists of thick deposits of gravel and sand to about fifteen feet, with thin beds of white clay.

Evidence of pre-Roman first Century occupation was also revealed at the edge of the plateau. On the south side of the Drive, west of Primrose Hill the vertical edge of a Gipping ice sheet was bisected and traced for a short distance westward. The area of Gipping Till is larger than is shown on the one inch geological map, extending south-westward beyond Sprites Hall Lane and into Chantry Park where it apparently thins out, the normal streaky base having been exposed in a trench parallel to London Road.

At Kesteven Road a Neolithic settlement was discovered at the old gravel pit on some twenty feet of gravel which extends down to the junction of Willoughby and Belstead Roads where Red Crag has been exposed. Saddle querns made of Sarsens from the river bed were used for grinding com.

Formerly there were brickyards in Burrell Road utilising London Clay and apparent Reading sands were temporarily revealed below Stoke Churchyard. Excavations in Vernon Street and Gower Street exposed boulder clay which may be Lowestoft Till.

Excavations for the new Telephone Exchange at Ipswich, were dug into thick deposits of gravel in the lower part of which a Mammoth tooth was found above the Gipping Till. Unbedded gravel with no indication of deposition by water, has been exposed at intervals from Barrack corner to Major's Corner. This, together with evidence from other sites, is regarded as a gravelly tili of the last (Hunstanton) glaciation of which the main ice sheet did not extend far into East Anglia and the Cromer Ridge probably marks the terminal moraine.

304 Transactions of the Suffolk Naturalists',

Vol. 13, Part 5

East of the Exchange large scale excavations for the underground car park were carried down to the chalk at Lady Lane.

Here only the Thanet Bed and the lower part of the Reading Sand were in situ at a depth of forty feet. The London Clay was found to have been sheared off and was discovered above the deposits of the Lowestoft glaciation of which a thrust moraine was well illustrated by the resulting formation on the north side, where deposits of the Gipping glaciation indicated pressure from the north also. Outwash sand and gravel was found present between the Reading Bed and the base of the Lowestoft Till which was tilted 80° to the west and 60° to the north and was exceptionally blue in colour. On the west side a thin Stratum of Gipping Till on Lowestoft Till, was succeeded by layers of fine sand and loessic silts below normal current bedded Gipping sands and gravel. Above all on the north-west face an unusual madder brown mainly fine grained deposit about four feet thick, probably belongs to the last glaciation, the deposits of which are seldom recognised.

Excavations for the new Civic Centre were entirely in sandy beds which may have the same relationship to the Lowestoft Till as the stoneless sands at Great Blakenham.

The "Orwell Flue", an arm of the Gipping now mainly bricked over, may possibly represent a former "oxbow" to which the low cliff at the town end of Handford Road and the Mount is due.

It runs from the first lock, via The Cattle Market to Stoke Bridge.

Deep trenches just south of St. Matthew's Churchyard exposed complicated structures due to ice pressure. Excavations on the former island at Constantine Road exposed fluviatile deposits with freshwater mollusca, mammoth and reindeer remains. With these were associated flint artifacts, including two fine "laurel-leaf" blades of the Solutrean industry. In lower Princes Street below ten feet of peat a weaving comb, made of deer antler, was discovered dating from the Early Iron Age which implies the peat accumulated in about two thousand years.

Ipswich owes its origin to the very numerous springs at the junction of the Red Crag with the London Clay which provided abundant water for both prehistoric and Anglo-Saxon settlers.

It is due to the action of these springs that the lateral Valleys have been formed and the process can be seen at Beggar's Hollow, Clapgate Lane, where at present the local authority is filling the Valley with refuse. The process consists of the spring water washing out unconsolidated sand and small shells forming a small, cavernous hollow of which the roof eventually collapses. T h e fallen material is in turn removed and the cycle begins again, thus the head of the Valley encroaches further into the plateau and is modified by drainage therefrom. Where these Valleys are from

GEOLOGICAL

IIISTORY

305

east to west the north facing slope is usually steeper because in winter the low sun cannot thaw the frozen surface. South facing slopes however are more often gradual because the thawed soil tends to slip downhill and the process is assisted by rainwash.

If there are side springs small lateral Valleys are developed, these are unusual but Beggar's Hollow was one example of which only one side Valley survives, that on the south has been levelled and now is a recreation ground.

Floghighland On the south side of Beggar's Hollow is a spur known as Hoghighland from the fact that pigs were once kept near the west end where the London and Reading Clays were exploited for brick and tile making at Gardiner's Brickyard. T h e stream from the Valley had cut down into the chalk just south of Cliff Brewery where the Bullhead Bed was exposed on the foreshore before the construction of Cliff Quay. For infilling behind the piling the end of the spur was cut back during the last stage of construction and the resulting section was given in Part 1 (FIG. 2). T h e site is notable for the exposure of Oldhaven Sand which was supposed not to occur in the region. This grey sand deposit was presumably destroyed by the London Clay Sea and the sparsely dispersed bluish flint pebbles therein became concentrated as the basement bed of the London Clay. T h e dorne shaped section of Oldhaven Sand lies conformably on the Reading Beds, which at this point are mainly sandy, but with a very marked unconformity below the London Clay. T h e teeth of sharks appear to be frequent and numerous fragments of crushed fragile shells were seen but nothing identifiable found. Another smaller outlier of Oldhaven Sand was noticed at Bobbitshole in the Belstead Brook Valley (GR 145419). Below the Sand, borings about half an inch in diameter up to six inches deep, made by marine organisms were found in the top of the Reading Bed. T h e London Clay was apparently deposited near a land mass with large rivers like the Amazon and Mississippi which annually convey vast quantities of Sediment into the ocean. In Suffolk it is extremely poor in fossils of which the pyritised wood is most abundant in places like the foreshore below Bridge Wood (GR 185403). Twigs, etc., of Cercidiphyllum spenceri, Brett, have been found embedded in blocks of Septaria. Once a group of the shells of Aporrhais sowerbii was discovered in one block and another contained a mixed group including:— Aporrhais triangulata, Gardner Dosinopsis orbicularis, Morris Nuculana partimstriata, Wood Sigata abducta, Deshays.

Buccinum concinnum, Sowerby Modiolus simplex, Sowerby Scaphander parisiennsis, d'Orb.

306 Transactions

of the Suffolk

Naturalists',

Vol. 13, Part 5

Resting on the L o n d o n Clay the Basement Bed of the Red Crag was f o u n d to be of an exceptional character consisting of fairly large rounded lumps, or boulders, of L o n d o n Clay amongst which the usual "coprolites", etc., were sparsely distributed. About a quarter of a mile to the south this bed at a lower level was normal b u t less thick with derived crustacean fossils from the L o n d o n Clay.

Above the Crag sands the plateau gravels were exposed in numerous sections behind the Cliff Quay Power Station and proved to be complex. Normally one would expect Gipping gravel of Creeting type and in all probability this is represented b u t the Gipping Till is represented only by rafts included in the upper gravel T h e lower gravel has been channelled and coarse gravels with Sarsen erratics f r o m the Reading Sand fill the Channels.

S o m e parts tend to be of Cannon Shot character with large spherical fiints.

A recent section in a deep trench at W y e Road ( G R 181430) revealed five to six feet of coarse u n b e d d e d morainic gravel with an argillaceous matrix which could be one of the extreme forms of Gipping Till or possibly the gravelly tili of the last glaciation, of which the main ice sheet did not reach so far south. Below this is three to four feet of grey clay resting on the Red Crag S a n d ; this may possibly be an outlier of the Baventian Clay but it could be a glacial lake deposit. T h e hill slope behind the Power Station is largely rainwash of decalcified Crag Sand and it contains scattered flint artifacts, like those f o u n d at the bottom of Beggar's Hollow in similar sand.

Piper's V a l e T h e base of the Crag slopes down to the shore level at the n o r t h end of Piper's Vale and before the construction of the Power Station ash disposal area shells, notably Neptunea contraria, were scattered by the higher tides on the foreshore. F o r m e r shelly Crag pits at each end of Piper's Vale have been long overgrown. Shelly Crag was exposed during the construction of the swimming pool. Originally the end of the high s p u r crossing the Vale apparently terminated in a cliff which collapsed some five thousand years ago. T h i s is proved by the subsequent establishment of the Neolithic settlement close to the never failing Crag springs. T h e black Stratum, two feet or more thick a n d fĂźll of b u r n t flints (cooking stones), is a cooking floor indicating prolonged occupation and it extends some sixty feet along the bank just above the high spring tide level. It is normally hidden behind the reeds. At the edge of the sand patch, ( G R 176415), below the grass roots is a series of thin black layers representing repeated burial of turf by sandy hillwash, an indication of present day geological processes. T h e sand itself contains scarce flint artifacts and shards of pottery have been f o u n d typical of the

GEOLOGICAL

HISTORY

307

Beaker Period. From the landslide a short length of London Clay cliff extends downstream to King John's Ness, the site of a former shipbuilding yard, near Pond Hall.

DĂźring the 1953 storm the talus which usually masks the Ness cliff was washed away exposing a complete section (FIG. 11).

London Clay formed an earlier clifF against which Red Crag with highly inclined bedding and Brickearth of Stutton type has been banked. The Brickearth was evidently deposited in stages, at each stage a small London Clay talus formed and this in turn became buried by more brickearth. The brickearth is mammaliferous but only one tooth of a young horse has been collected at this site. The gravel at the top of the section is apparently part of the brickearth (stony brickearth) the upper part of which is contorted by solifluction.

A small stream flows into the Orwell at this point where an alluvial flat is now being eroded by the tides but to judge from the worked fiints therein it was deposited in the Mesolithic period. Thirty years ago a cart track from Pond Hall led along the shore between the bank and a salting extending from the stream to Bridge Wood and about fifty yards wide, except for a very few Square feet at the south end this has been washed away.

The low bank is mainly brickearth with solifluction phenomena with a Neolithic horizon above, below the subsoil.

The next feature of the shore is a gravel cliff of about the same age as the Brickearth from which a limb bone of a horse is said to have come. From the cliff to the south end of Bridge Wood the surface of the London Clay has been denuded and steep sided Valleys give a marked undulating character to this side of the estuary down to Alnesbourne Priory. At the Priory end of the Wood, the end of a spur about seventy-five feet high collapsed perhaps some 200 years ago, to judge from the oaks growing on the still sharp ridges formed by the landslide. On the fallen surfaces there are traces of the Red Crag Basement Bed below decalcified Crag sand.

From Bridge Wood to Broke Hall the shore is low lying with three-quarters of a mile of salting with Samphire, Sea Lavender, etc. At the Mulbcrry Middle end westerly winds are the cause of the present accumulations of sand which form a spit that will in time enable the salting to extend upstream. The bed of Reeds, amongst the stems of which floating debris is trapped, helps to build up the shore level at this point and may play some part in the development now in progress. The lower end of the salting is suffering severe erosion and has receded some distance in recent years, an indication the natural processes of deposition and denudation proceed continuously in places.

308 Transactions of the Suffolk Naturalists', Vol. 13, Part 5 A small but strongly flowing streamlet from the Crag springs near the Priory joins the Orwell here.

Nacton Shore In the low river bank and both sides of the lane to the shore from Nacton village there are traces of Brickearth, this is stony in places and near Broke Hall it has become partly mixed with London Clay either by ice pressure or solifluction (GR 221389).

From Broke Hall toward Levington Creek there is another cliff of London Clay in which a landslide occurred only a few years ago.

Stratton Hall From the Creek to Sleighton Hill, Trimley (GR 255373), the shore is low and marshy owing to the spring water from the Crag, which is exposed in a small pit south-east of Stratton Hall. The Stratton Hall sea wall was damaged in 1953 and has not been repaired. Sleighton Hill terminates in a small cliff with a trace of the Crag Basement Bed on top. Except for a short Stretch of Fagborough Cliff near the Walton border it is all marshland to Landguard Common.

Felixstowe Formerly the River Stour flowed straight across the Landguard marsh area, traditionally into Hollesley Bay which is now silted up. Landguard was an island administered by Essex. The old sea cliff runs from Walton Ferry to Felixstowe pier consisting of London Clay capped with Red Crag and some gravel. Bomb craters on Landguard Common revealed shingly beach deposits proving the area is of recent origin.

Up to the 1914-18 period much of the Felixstowe Cliff was rather rugged weathered Red Crag with an abundance of shells; most of this is now concealed by steps, terraces, and gardens.

The Spa Pavilion commemorates a well 177 feet deep from which "Spa" water was sold for its medicinal properties; an advertisement of July, 1891, on the authority of "Dr. J. E. Taylor, F.L.S., F.G.S., etc." stated "It contains dissolved Chloride of Sodium, Carbonate of Lime, Magnesia, Iron, and Phosphates. The last is an important element, as it makes the water a capital medicine for those suffering from nervous prostration, depression, and overwork."

It was also claimed to be of the same class as the celebrated Continental waters of Weisbaden, etc.

The upper half of the cliff is Red Crag resting on London Clay which has only been exposed in recent years at Brackenbury Fort and large crystals of gypsum collected.

GEOLOGICAL HISTORY

309

On the soiith side of the pier up to 1914 the beach was very narrow and the shingle was cast up on the Promenade, it is now much wider showing the accumulation of shingle which built up Landguard Marshes continues.

Ipswich Returning to the right bank and proceeding downstream from the Chantry Estate we find that the former Crag pit near Gippeswyk Hall has been levelled and built over.

A strong spring from the Red Crag in the lower part of Birkfield Drive supplied water to Gippeswyk Hall and in all probability to the Neolithic settlement on the gravelly hill in Kesteven Road some 4,000 years earlier.

Ipswich Dock From the Dock the river flows southward to Bourne Bridge where it receives the water of Belstead Brook. The construction of the dock began in 1839 by closing at each end a bend of the river and the original lock gates were in the New Cut made to bypass the river water. A well at Cranfield's Flour Mill penetrated:— Boulder clav Sand a n d shells Fine sand Shingle and sand Pale l o a m Boulder clay a n d septaria R e d loamy sand R u n n i n g sand Chalk to

3' 4J' 3J' 3' 4' 4' 1' 4' 81'

2 7 ' t o chalk

108'

These deposits evidently represent the Alling at the margin of the buried Channel. At the Cliff Brewery the top of the chalk was exposed at half tide.

The Stoke Hill Beds Düring the construction of the railway in the 1840's bones of prehistoric animals were discovered, a few of which are in the Ipswich Museum. In more recent years two further excavations were made by Miss N. F. Layard (niece of Sir Hy. Layard) when a fully representative fauna was collected, it includes:— Mammoth Rhinoceros Horse Deer Wild O x Bison

Mammuthus primigenius indeterminate Equus caballus Cervus elaphus Bos primigenius Bison priscus

mostly y o u n g animals a large t y p e — c o m m o n fairly c o m m o n fairly c o m m o n rare

310 Transactions of the Suffolk Naturalist?, Bear Tiger, or ?Iion Wolf Fox Bird Reptile Mollusca

Vol. 13, Part 5

Ursus sp. rare Panthera (Felis) cf tigris rare Canis lupus rare C. vulpes rare undetermined Emys orbicularis scarce undetermined, shells crushed by pressure.

The greater part of the fauna is generally represented in other deposits of the same age but only in recent years have remains of the South European Pond Tortoise been discovered at other sites, at Bobbitshole and Stutton. At the latter place Emys is associated with Corbicula fluminalis not now found living nearer than the R. Nile. The association of these with a MammothRed Deer fauna is an indication of a warmer climate for the period.

The bones of a forefoot originally attributed to Cave Lion, belonged to a very large and aged beast and in view of the determination of the presence of tigers in SufTolk they are now referred to that species.

Most of the bones are from a thick bed of brownish loam or clay, others came from the Black Bone Bed of Miss Layard and a few from a seam of white clay near the Halifax signal box. The horses and wild oxen are indicative of open grassland in the district, while the Red Deer and wolf imply woodland; a conclusion confirmed by the fauna in the Stour Valley of the same age.

The Stoke Hill Beds occur about thirty feet above the present river proving that the Orwell-Gipping Valley 100,000 years ago was unlike it is today. A small outlier of the Eocene mottled Reading Clay at the Halifax box suggests a bend in the river which became an oxbow lake. To the west of the Reading Clay islet, in an exceptionally deep trench, the mottled clay passed down into a very fine sand similarly mottled with crimson blotches of Haematite. Across the river at the Power Station site, in one section the Haematite blotches were seen to be drawn out vertically for about a foot and then curved over to the west for six inches or so, then fading out; nothing like this has been observed elsewhere.

Belstead Brook—Bobbitshole About a mile to the south-west of the railway tunnel is Bobbitshole where excavations for a new sewage disposal works exposed a series of beds not previously recorded for the area. The site was discovered by the writer in 1952 during the course of his examination of the system of trenches for the Chantry Estate and their scientific importance led to invitations being extended to other geological specialists in order that all possible data might be obtained. The most important results were obtained by Dr. R. G. West and B. W. Sparks of Cambridge and are published in the Philosophical Transactions of the Royal Societv fVol 241 J V pp. 1-44, 1957).

GEOLOGICAL HISTORY

311

The description of the local stratigraphy by Dr. West is based on Boswell's 1927 Ipswich Survey Memoir and because of the lack of earlier excavations in the Valley bottom this is inaccurate.

The 1952 trenches from Bobbitshole to Bourne Bridge enabled the earlier erroneous conclusions to be corrected. The fact is Belstead Brook has cut its bed down into the top of the chalk the surface of which is only about thirty inches down near the railway, and the stream for the last mile flows in a C h a n n e l in the chalk. The whole of the Eocene formations having been eroded. Near Belstead House however the Brook flows along a C h a n n e l in Gipping Till.

From the railway westward along the right bank an escarpment only a few feet high marks the former limit of the high tides when this part of the stream was a tidal creek, before the railway was constructed. At that time the Bullhead Bed at the top of the chalk was exposed on the foreshore and prehistoric man came there to collect the flints for the manufacture of stone artifacts, leaving the waste chips behind. These were found to be included in a deposit formed of hillwash from the loess on the slope above.

The Bobbitshole beds include:— Fluvio-glacial gravel of the last glacial period lying on loess to the south and over the lake beds near the stream.

The loess at the southern margin was yellowish of an argillaceous character when wet but like a very fine dust in a dry condition and when rubbed between the fingers feels as fine and smooth as talcum powder. Here sixteen feet was proved by boring, the base not being reached. The surface was markedly irregulär below Gipping Till of which only the edge was exposed.

West assumed this tili had slipped down from the plateau above but it is undoubtedly in situ as similar circumstances exist at Bramford Road. Loess was also exposed in the Valley bottom below the peaty detrital mud of the lake bottom; an attempt to ascertain its thickness was defeated by the gruel-like consistency of the saturated rock when disturbed by the boring tool. Particular attention was given to the loess, the first to be scientifically determined as such in SulTolk, the analysis was made by Dr. I. W. Cornwall, whose report is as follows:—"Your sample turns out to be a quite typical calcareous (and therefore unweathered) loess:— Sand Silt Clay

( > 0-006 mm) 8% ( > 0-006-0-002 mm) 81% ( < 0-002 mm) 11%

there is no question that it is a wind sorted Sediment—a better loess even than the now famous Ebbsfleet series" in Kent. Dr. West's opinion that it was deposited in water is disproved by the marked absence of bedding characteristic of water laid deposits in the district with similar fine grained material.

312 Transactions of the Suffolk Naturalists',

Vol. 13, Part 5

The lowest lake deposit was rieh in non-marine mollusca with remains of perch and other fishes, also small amphibia (Pnewts).

This detrital mud contained quantities of twigs, etc., and hazel nuts and teeth of small rodents imply that these mammals were abundant while the lake existed. The deposit appears similar to that at present being formed in decoy ponds surrounded with trees.

A calcareous clay was next in the series, which was blotched with ferrous oxide stains and equally rieh in shells, etc., but without fossil wood. It was in this bed scanty remains of larger mammals were found and these were fragmentary owing to the use of excavating machinery. The fauna included mammoth, bison, and red deer; the latter was represented by part of a radius which had been split by prehistoric man to obtain the marrow.

One bone of beaver from the lower mud was found and in consideration of the fact that thick deposits of gravel occupied the lake bed levels immediately downstream, it seems probable the lacrustrine formations may be due to a beaver dam.

The upper fluvio-glacial gravel contains marked of the strata that clearly indicates that a subsequent to which is due an ice cut Channel filled with a stony found to have removed the north side of the lake

over-folding cold period tili that was beds.

A trench along the Valley slope to Stone Lodge exposed sections of small glacial Channels, some only twelve feet wide, filled with an odd mixture of gravel, sand and patches of Gipping Till (some of these were deealeified). These can only be the record of tongues of ice Spilling over from the plateau feeding the small valley glacier which cut through the Bobbitshole beds.

In this trench a long section of the lower part of the Red Crag was exposed resting on the Reading Beds, the London Clay having been entirely eroded and represented only by much weathered blocks of Septaria forming the Basement Bed of the Crag.

At the rear of Belstead Brook House an extraordinary deposit of waterlogged Reading Clay brecchia about ten feet thick was exposed which possibly is the result of a scree-like talus formed during a cold dry period at a former cliff face and subsequently quickly buried.

Belstead Brook originates at about 260 feet O.D. in the parish of Naughton and flows via Elmsett, Burstall (where it reeeives small tributaries) and Washbrook; like the other streams of the system it drains the chalky boulder clay uplands. At Flowton stones in the shallows become encrusted with a rough grey calcareous deposit similar to that produced by so-called petrifying springs.

PLATE

1

P a r t o f t h e east s e c t i o n o f t h e H a d l e i g h â&#x20AC;&#x201D; L o n d o n R o a d r a i l w a y c u t t i n g , 1934, s h o w i n g t h e m u c h d i s t u r b e d strata r e s u l t i n g f r o m ice p r e s s u r e as t h e G i p p i n g G l a c i e r passed r o u n d t h e h e n d i n t h e Valley.

Gipping T i l l

{

« '

«A»

^

r c* ^ Undermelt deposit

G i p p i n g outwash Gravel and sand

Lovvestoft T i l l Baventian Clay •Siliceous non-flint and flint gravel passing d o w n into Creeting W h i t e Sand

Chalk

FIG.

6

Ideal section at Creeting St. M a r y showing the sequence of deposits. ( N o t to scale).

FIG. 7

U p p e r part of chalk section i n the old chalk quarry at Great Blakenham.

1 crushed chalk, 2 sections of sand filled Channels formed by melt water, 3 normal chalk Solution pipe, 4 chalk. F r o m a photograph.

FIG.

8

1 natural chalk, l a edge of ice cut Channel, 2 chalk indurated w i t h secondary Calcium carbonate, 3 G i p p i n g T i l l , 3a indurated t i l i at margin of ice, 4 Channels cut by sub-glacial streams originally filled w i t h sand, 5 soft t i l i washed out by rain.

FIG.

9

Section exposed i n 1947 showing part of the south side of the Channel cut i n the chalk by Lowestoft ice. 1 displaced chalk, 2 gravel deposited by sub-glacial melt water, 3 chalk in situ, 4 fine sand and small stones. Assoc.

Portland Cement Co's. quarry, Great Blakenham.

FIG.

10

Section on the opposite side of the c u t t i n g showing abnormal bedding of sand deposited by m c l t water flowing between Lowestoft T i l l and the chalk at the m a r g i n of the glacier. Section novv obscured by talus. Height about 8 feet.

London Clay

Red Crag FIG.

11

Representation of the cliff at K i n g John's Ness on the left shore of the Orwell, near Ipswich, as it appeared after the storm of 30th January, 1953.

GEOLOGICAL

HISTORY

313

Frestonâ&#x20AC;&#x201D;Wherstead Red Crag was exposed when cuttings through both Wherstead and Freston Hills were widened and it must be noted that loads of shelly Crag sand were conveyed to Earl Stonham and dumped on the south side of the road to Stowmarket at GR 113588.

The right shore of the Orwell is obscured by the parkland to Pin Mill where streamlets from Crag springs merge before joining the main river. Downstream for about a mile the Crag cliff is overgrown and likewise the short cliff near Hill House, Shotley.

Several deep trenches at Shotley were dug entirely in decalcified and otherwise featureless Red Crag sand.