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Excursion to Epsom and Dorking
896
EXCURSION TO TILBURY DOCKS.
covered at many other places in its valley at heights of from 20ft. to 50ft. above the present stream. Now it is evident that to class together under the name palreolitbic human remains or implements found in these older alluvial beds and those of the recent alluvium of Tilbury marshes is to ignore the great interval of time indicated by the change in the physical geography of the district, and to group together the relics of widely separated eras. Every member of the party must have felt how much the pleasure of the excursion was due to the dryness of the weather, which allowed of the free ascent and descent of the clay slopes without the slightest inconvenience. About forty visitors returned to London by an early train, the remaining sixty crossing the river to recruit their exhausted energies at the New Falcon Hotel.
EXCURSION
TO
EPSOM
AND
DORKING.
MAY 24TH, 1884. Directors :-W. H. DALTON, F.G.S., of the Geological Survey, and H. H. FRENCH. ~RepQrt
by
MR. DALTON.)
On arriving at Epsom, shortly before noon, the party proceeded by pleasant country roads and lanes to the Downs. Here, at the back of the rifle butts, they examined a pit in the Upper Chalk, the beds of flint in which served as indications of the amount of dislocation of a fault which throws down the beds about eight feet to the south-east. Several slickensided faces were observable on joint planes of parallel direction, and although such surfaces have been attributed to pseudomorphism of aragonite, &c., it was agreed that no such hypothesis was requisite in such cases as the present, where relative movements of the different portions of rock were in evidence. At one point of the fault a vertical sheet of flint had been formed, probably by replacement of chalk in water occupying a temporarily-open fissure. Traversing the race-course, where preparations for the approaching" Derby" were in full swing, the party ascended the hill on which stands the village of Walton. The summit of the hill consists of a thin sheet of Thanet Sand, overlaid with crimson-mottled brickearth and gravel. An old brickyard here was open in 1860, when Mr. Whitaker saw a section in the Thanet Sand, eight feet deep, under the brickearth. Speculations were rife among the party as to the course of the
EXCURSION TO EPSOM AND DORKING.
397
river which formed this gravel, and as to the cause of the survival of the Thanet Sand outlier, some maintaining its probable protection by beds locally harder than usual (although the several outliers reach to different horizons of the Lower Tertiary series), whilst others preferred the hypothesis of a slight synclinal undulation parallel to the general strike of the Chalk and Tertiaries, patches of the latter being preserved in a discontinuous trough ranging for about eight miles, Walton being nearly midway between the extremities. On Walton Heath some typical exposures of " clay with flints" were visited, and the Directors of the party were pressed, but in vain, to commit themselves, jointly or severally, to one of the many theories of the origin of this deposit. That which attributes it to the solution of chalk by percolating water plus relics of Tertiary beds is the theory which in these days of compromise and tolerance is perhaps the safest. The thickness of the deposit and its continuous occurrence along the escarpment attest the great denudation which the Chalk has undergone. From the heath a fine view was obtained of Pebble Hill and Leith Hill, the former being part of the Chalk escarpment close by, whilst Leith Hill is on that of the Lower Greensand several miles to the south-west. Descending the hill by a deep-cut road, whose high banks thickly sprinkled with wild flowers and herbage, only showed the Chalk, decomposed into amorphous marl, at intervals, the botanical members of the party discussed the floral beauties they met with, and the previously compact group became a straggling chain, to be re-united on reaching a large pit in the Upper Greensand, where, under a head of Chalk rubble, was seen the Chloritic Marl, highly fossiliferous, overlying tho Hearthstone beds, for which the pit is opened. The two divisions are of very similar lithological character, calcareous clayey sand, with abundant glauconite grains, which on a surface bruised by a frictional stroke of the hammer form green streaks. The absence of fossils from the Hearthstone appears to be the only difference noticeable. The Chloritic Marl and the Chalk rubble are carried across the pit on staging, and the Hearthstone is raised vertically by a windlass from the floor of the pit. At a lower level occnrs the Firestone, used for furnace-lining, &c., to obtain which slanting tunnels have been carried far in under the hill. This stone has also been used for building, for instance, in Windsor Castle and in Henry VIII.'s Chapel, Westminster Abbey. Passing through Betchworth, the party next entered a large pit
398
EX CURS IO N TO EPSOM AN D DORRI N G.
in the Lower and Middle Chalk, the Upp er Chalk having been denud ed back from th e escarpment. The local name here is " grey ston e," in contradi st inction to the white Upp er Chalk. A considerable number of nodules of iron pyrites were here noticed in the lower part of th e pit, generally un altered within, th ough oxidised t o a rich rust colour on th e surface: in th e proximity of joints, however, th e oxidat ion exte nded deeper, and in small nodules was complet e. Th e chemical action consist s in th e absorpt ion of oxygen dissolved in percolat ing water , forming ferric sulph ate , which by conta ct with the sur rounding Chalk forms sulphate of lime and carbonate of iron, th e latter speedily passing, by addition of further oxyge n, into th e red peroxide of iron. F ew fossils were obtained from this pit , but in another close by were purchased from th e workmen some fragments of fish remain s, and some of the char acteristic sheJls, T erebratula, &c. The elaborate kil ns here used for burnin g th e chalk into lime were examined with much interest, and th e party the n defiled along the narrow winding wood-embosomed path known as th e Pil grim 's W ay (which extends from Alton, in Rants, to Cant erbury), to th e Brockham brick and firestone pits, where the lower beds of th e Upper Gr eensand, and nearly th e highest-of th e Gault Clay are exposed, thou gh not in continuous section. Neith er are fossiliferous, and no long stay was here made, but it may be not ed that th e upper part of th e Gault section was crowded with nodules of "race," seg regations of carbonate of lillie from th e surrounding clay, and that thin veins of fibrous gypsum are formed by the decomposition of pyrites and neutralisati on by carbonate of lime, as described above. It may here be noted that th e P ilgrim 's Way on the Gault and Upper Green sand is bord ered almost continu ously by yew-trees, whil st east of Reigate, wbere it passes into the Lower Geensand, the ash replaces the yew, a st riking exampl e of th e relation between geological structure aud vegetation . The firestone h ere is work ed by tunnel, the rock at the mouth appearing to differ in no respect from th e Hearth st one previou sly examined. After half an hour's walk the Lower Greensand was reached at l\ mill turn ed by the Mole, and th e coarse ferr ugi nous sandstone was briefly examine" , This uppermost division is known as the Folkestone Beds, and its colour is due to peroxidat ion of its contained iron. A fine secti on of similarly t inted sand and sandst one
EXCURSION TO
EPSO~r
AND DORKING.
399
is exposed on the railway a short distance further west, but time did not permit of its examination j so the party pushed on to Dorking station, reaching it but a. few minutes before the starting of the return train.
EXCURSION TO CAMBRIDGE. WHIT-MoNDAY AND TUESDAY, JUNE 2ND AND BRD, 1884.
Director:-PROFESSOR T. McKENNY HUGHEfI, F.G.S. (Report by
TilE DIRECTOR.)
OU their arrival, the members met in the Woodward ian Museum, where they were received by the Woodwardian Professor, the Rev. Osmond Fisher, F.G.S., Rector of Harlton j the Rev. E. Hill, F.G.S., Fellow and Tutor of St. John's CoIl. j Dr. R. D. Roberts, F.G.S., Fellow of Clare Coll., and University Lecturer on Geology j Mr. J. E. Marr, F.G.S., Fellow and Lecturer on Geology, St. John's ColI. ; Mr. A. Harker, F.G.S., Demonstrator in Petrology j Mr. Thos. Roberts, F.G.S., Assistant to the Woodwardian Professor. Under their guidance, the Association, in groups, according to the various branches of the subject in which they were interested, spent the greater part of the day, examining the Geological Museum. The collections date from the middle of the 17th century j the oldest being that of Agostino Scilla, described in his work • La Vana Speculazione disingannata dal Sense,' which was published in 1670. This collection was acquired by Dr. Woodward, who continued to accumulate specimens of "native" and "extraneous" fossils in illustration of his views as to their origin until his death, in 1728, when he bequeathed most of them to the University. No great addition was made till the time of Sedgwick (18181873), who made the museum what it is-one of the richest educational museums in the world. Mr. Marr explained tho arrangement of the Cambrian and Silurian fossils, a collection which had been much enriched by the President of the Association (Dr. Hicks). Mr. Harker, assisted by Mr. Small, drew attention to some of the more interesting petrological specimens, and exhibited a series of illustrative slices under the students' microscopes. Tho Association then examined the stones employed in some of the more important buildings. The Mineralogical Museum was
EXCURSION TO TILBURY DOCKS.
covered at many other places in its valley at heights of from 20ft. to 50ft. above the present stream. Now it is evident that to class together under the name palreolitbic human remains or implements found in these older alluvial beds and those of the recent alluvium of Tilbury marshes is to ignore the great interval of time indicated by the change in the physical geography of the district, and to group together the relics of widely separated eras. Every member of the party must have felt how much the pleasure of the excursion was due to the dryness of the weather, which allowed of the free ascent and descent of the clay slopes without the slightest inconvenience. About forty visitors returned to London by an early train, the remaining sixty crossing the river to recruit their exhausted energies at the New Falcon Hotel.
EXCURSION
TO
EPSOM
AND
DORKING.
MAY 24TH, 1884. Directors :-W. H. DALTON, F.G.S., of the Geological Survey, and H. H. FRENCH. ~RepQrt
by
MR. DALTON.)
On arriving at Epsom, shortly before noon, the party proceeded by pleasant country roads and lanes to the Downs. Here, at the back of the rifle butts, they examined a pit in the Upper Chalk, the beds of flint in which served as indications of the amount of dislocation of a fault which throws down the beds about eight feet to the south-east. Several slickensided faces were observable on joint planes of parallel direction, and although such surfaces have been attributed to pseudomorphism of aragonite, &c., it was agreed that no such hypothesis was requisite in such cases as the present, where relative movements of the different portions of rock were in evidence. At one point of the fault a vertical sheet of flint had been formed, probably by replacement of chalk in water occupying a temporarily-open fissure. Traversing the race-course, where preparations for the approaching" Derby" were in full swing, the party ascended the hill on which stands the village of Walton. The summit of the hill consists of a thin sheet of Thanet Sand, overlaid with crimson-mottled brickearth and gravel. An old brickyard here was open in 1860, when Mr. Whitaker saw a section in the Thanet Sand, eight feet deep, under the brickearth. Speculations were rife among the party as to the course of the
EXCURSION TO EPSOM AND DORKING.
397
river which formed this gravel, and as to the cause of the survival of the Thanet Sand outlier, some maintaining its probable protection by beds locally harder than usual (although the several outliers reach to different horizons of the Lower Tertiary series), whilst others preferred the hypothesis of a slight synclinal undulation parallel to the general strike of the Chalk and Tertiaries, patches of the latter being preserved in a discontinuous trough ranging for about eight miles, Walton being nearly midway between the extremities. On Walton Heath some typical exposures of " clay with flints" were visited, and the Directors of the party were pressed, but in vain, to commit themselves, jointly or severally, to one of the many theories of the origin of this deposit. That which attributes it to the solution of chalk by percolating water plus relics of Tertiary beds is the theory which in these days of compromise and tolerance is perhaps the safest. The thickness of the deposit and its continuous occurrence along the escarpment attest the great denudation which the Chalk has undergone. From the heath a fine view was obtained of Pebble Hill and Leith Hill, the former being part of the Chalk escarpment close by, whilst Leith Hill is on that of the Lower Greensand several miles to the south-west. Descending the hill by a deep-cut road, whose high banks thickly sprinkled with wild flowers and herbage, only showed the Chalk, decomposed into amorphous marl, at intervals, the botanical members of the party discussed the floral beauties they met with, and the previously compact group became a straggling chain, to be re-united on reaching a large pit in the Upper Greensand, where, under a head of Chalk rubble, was seen the Chloritic Marl, highly fossiliferous, overlying tho Hearthstone beds, for which the pit is opened. The two divisions are of very similar lithological character, calcareous clayey sand, with abundant glauconite grains, which on a surface bruised by a frictional stroke of the hammer form green streaks. The absence of fossils from the Hearthstone appears to be the only difference noticeable. The Chloritic Marl and the Chalk rubble are carried across the pit on staging, and the Hearthstone is raised vertically by a windlass from the floor of the pit. At a lower level occnrs the Firestone, used for furnace-lining, &c., to obtain which slanting tunnels have been carried far in under the hill. This stone has also been used for building, for instance, in Windsor Castle and in Henry VIII.'s Chapel, Westminster Abbey. Passing through Betchworth, the party next entered a large pit
398
EX CURS IO N TO EPSOM AN D DORRI N G.
in the Lower and Middle Chalk, the Upp er Chalk having been denud ed back from th e escarpment. The local name here is " grey ston e," in contradi st inction to the white Upp er Chalk. A considerable number of nodules of iron pyrites were here noticed in the lower part of th e pit, generally un altered within, th ough oxidised t o a rich rust colour on th e surface: in th e proximity of joints, however, th e oxidat ion exte nded deeper, and in small nodules was complet e. Th e chemical action consist s in th e absorpt ion of oxygen dissolved in percolat ing water , forming ferric sulph ate , which by conta ct with the sur rounding Chalk forms sulphate of lime and carbonate of iron, th e latter speedily passing, by addition of further oxyge n, into th e red peroxide of iron. F ew fossils were obtained from this pit , but in another close by were purchased from th e workmen some fragments of fish remain s, and some of the char acteristic sheJls, T erebratula, &c. The elaborate kil ns here used for burnin g th e chalk into lime were examined with much interest, and th e party the n defiled along the narrow winding wood-embosomed path known as th e Pil grim 's W ay (which extends from Alton, in Rants, to Cant erbury), to th e Brockham brick and firestone pits, where the lower beds of th e Upper Gr eensand, and nearly th e highest-of th e Gault Clay are exposed, thou gh not in continuous section. Neith er are fossiliferous, and no long stay was here made, but it may be not ed that th e upper part of th e Gault section was crowded with nodules of "race," seg regations of carbonate of lillie from th e surrounding clay, and that thin veins of fibrous gypsum are formed by the decomposition of pyrites and neutralisati on by carbonate of lime, as described above. It may here be noted that th e P ilgrim 's Way on the Gault and Upper Green sand is bord ered almost continu ously by yew-trees, whil st east of Reigate, wbere it passes into the Lower Geensand, the ash replaces the yew, a st riking exampl e of th e relation between geological structure aud vegetation . The firestone h ere is work ed by tunnel, the rock at the mouth appearing to differ in no respect from th e Hearth st one previou sly examined. After half an hour's walk the Lower Greensand was reached at l\ mill turn ed by the Mole, and th e coarse ferr ugi nous sandstone was briefly examine" , This uppermost division is known as the Folkestone Beds, and its colour is due to peroxidat ion of its contained iron. A fine secti on of similarly t inted sand and sandst one
EXCURSION TO
EPSO~r
AND DORKING.
399
is exposed on the railway a short distance further west, but time did not permit of its examination j so the party pushed on to Dorking station, reaching it but a. few minutes before the starting of the return train.
EXCURSION TO CAMBRIDGE. WHIT-MoNDAY AND TUESDAY, JUNE 2ND AND BRD, 1884.
Director:-PROFESSOR T. McKENNY HUGHEfI, F.G.S. (Report by
TilE DIRECTOR.)
OU their arrival, the members met in the Woodward ian Museum, where they were received by the Woodwardian Professor, the Rev. Osmond Fisher, F.G.S., Rector of Harlton j the Rev. E. Hill, F.G.S., Fellow and Tutor of St. John's CoIl. j Dr. R. D. Roberts, F.G.S., Fellow of Clare Coll., and University Lecturer on Geology j Mr. J. E. Marr, F.G.S., Fellow and Lecturer on Geology, St. John's ColI. ; Mr. A. Harker, F.G.S., Demonstrator in Petrology j Mr. Thos. Roberts, F.G.S., Assistant to the Woodwardian Professor. Under their guidance, the Association, in groups, according to the various branches of the subject in which they were interested, spent the greater part of the day, examining the Geological Museum. The collections date from the middle of the 17th century j the oldest being that of Agostino Scilla, described in his work • La Vana Speculazione disingannata dal Sense,' which was published in 1670. This collection was acquired by Dr. Woodward, who continued to accumulate specimens of "native" and "extraneous" fossils in illustration of his views as to their origin until his death, in 1728, when he bequeathed most of them to the University. No great addition was made till the time of Sedgwick (18181873), who made the museum what it is-one of the richest educational museums in the world. Mr. Marr explained tho arrangement of the Cambrian and Silurian fossils, a collection which had been much enriched by the President of the Association (Dr. Hicks). Mr. Harker, assisted by Mr. Small, drew attention to some of the more interesting petrological specimens, and exhibited a series of illustrative slices under the students' microscopes. Tho Association then examined the stones employed in some of the more important buildings. The Mineralogical Museum was