Excursion to Bushey, Oxhey, and Watford Heath

278

EXCURSION TO BUSHEY, OXHEY, AND WATFORD HEATH.

and now inviting further criticism from the more numerousreaders of the PROCEEDINGS. NOTE BY THE EXCURSION SECRETARY,

A. C.

YOUNG.

At 4 p.m, the members motored back to Cambridge via Foxton and Trumpington, At Clare College they were sumptuously entertained by Prof. and Mrs. Hughes in the College Hall, after which a very hearty vote of thanks was accorded to our hosts. At 6 p.m. members proceeded to the Sedgwick Museum, where the Director and his assistants, especially Mr. R. H. Rastall, conducted them over the various galleries, lecture rooms, students' working rooms, libraries, etc., and the Director discoursed in his peculiarly interesting way on some of the more interesting specimens and those which had special reference to the Barrington gravels visited during the afternoon. At 7.3° the members strolled about the" backs" of the Colleges and other places of interest, and returned to London by the 8.45 train.

EXCURSION TO BUSHEY, OX HEY, WATFORD HEATH. SATURDAY, JUNE 24TH,

AND

1911.

Directors: H. KIDNER, F.G.S., AND J. H. WOODHEAD, F.G.S. Excursion Secretary: G. J. ROBERTS. (Report by

MR. KIDNER.)

A PARTY of 22 were met at Bushey by the Directors about 3 p.m. The Hertfordshire Natural History Society took part in the excursion. The party was conducted southwards through the Bushey Cutting. Mr. Woodhead explained that by the platform at Bushey Station there had been found a mass of Chalk 3 or 4 ft. higher than the general level of the Chalk surface, and at the top of the Chalk there were a number of large nodular flints. Immediately south of the platform, near the signal box, the" bottom bed" of Reading pebbles occurs; and Mr. Woodhead said that from the signal box all the way to the first bridge, and a few yards beyond, the rail way line is on the "bottom bed" of pebbles, excepting two or three places where higher beds have been let down by dissolution of the Chalk. Irnrnediatelv south of the signal box, the" bottom bed" had been seen to "a thickness of 7 ft. The top of the bed was about 4 or 5 ft. above the level of the rails, and its total thickness here apparently cannot be more than 8 to 10 ft. The writer described

PROC. GEOL. A~SOC" VOL.

XXII.

PLATE

XLI.

FIG. I.-ELEPHANT AND RHIN OCEROS IN THE BARRINGTON BEDS.

J

If

/I

FIG . 2.-HI PporOTAMUS IN THE BARRINGTON BE DS.

To fa ce page

278 .

EXCURSION TO BUSHEY, OXHEY, AND WATFORD HEATH.

279

a section which he had seen south of the Bushey Station signal box. An excavation along the highest part of the retainingwall exposed the beds for about 40 yards to a depth of 7 or 8 ft. At each end of the section could be seen the "bottom bed" of Reading pebbles, but in the middle part of the section, for about 30 yards, the pebble-bed had disappeared, owing to dissolution of the Chalk, and higher beds of sand and pebbles had been let down so as to form a synclinal trough between the two ends of the pebble-bed. The" bottom bed" presented a striking contrast to the higher beds of pebbles. Its matrix was a greenish clayey sand, coarser than the usual pale sand of the Reading series, and giving to the pebble-bed the appearance of ordinary gravel as described by Prestwich. * The pebbles were mostly small, averaging less than one inch. A few were considerably larger. A little to the south of the retaining-wall the beds appeared to have undergone disturbance through dissolution of the Chalk. Midway between the Bushey Station and the bridge the bed of pebbles was a remarkable sight. Recent rains had removed the sandy matrix, and along the bottom of the cutting as far as the bridge nothing but pebbles could be seen. The pebbles were all of flint, mostly black, averaging about an inch, but some two or three inches. The top of the pebble-bed, which was 5 ft. above the railway lines near Bushey Station, instead of dipping with the beds, as would be expected, increased in height southwards to 7 and 8 ft. above the lines opposite the Engine House. It appears, therefore, that between Bushey Station and the bridge the pebble-bed thickens rapidly to at least IS ft. Close up to the bridge shown in the illustration, and on both sides of it, the pebble-bed was seen by the party j and a few days later the writer saw a clean-cut section of the pebble-bed and overlying sand close to the unfinished wall shown south of the bridge. The top of the bed here was 4~- ft. above the rails, and the division between the pebble-bed below and the greenish Reading sand above was clear and sharp. There were very few scattered pebbles in the sand above the pebble-bed. The matrix of the bed of pebbles was slightly clayey and greenish above j but a shallow hole showed that the matrix was brown below. The colour of the Reading sand immediately north of the bridge varied, being brown above, pale or white in the middle part, and green below. In about 80 yards the pebble-bed rapidly disappears south of the bridge. Close to the northern side of the bridge about 3 ft. of brown loam was seen, but it is doubtful whether this was any part of the" basement bed" of the London clay in situ. Beneath the loam, less than 3 ft. of Reading clay was seen, but in a few yards northward this was cut out by later gravel, which then rests on the Reading sand. Near the bridge, on its southern side, the Reading clay

* Quatt.lOllm. Geol. Soc., vol, x, p. 9'.

280

EXCURSION TO BUSHEY, OXHEY, AND WATFORD HEATH.

above the sand is 5i ft. thick. Concurrently with the rapid disappearance of the pebble-bed here at the bottom of the cutting, and with the assumed thinning of the pebble-bed south of the bridge, the Reading clay thickens gradually to 6 ft. midway between the two bridges, and then somewhat rapidly to 10 ft. or more near the southern bridge, where it is mottledgreen and red. Here Mr. Woodhead, with regret, was obliged to take leave of the party. From measurements and levels. taken by Mr. Woodhead, and the writer's observation of the beds on frequent occasions, the section at that part of the Bushey Cutting, shown in the illustration, is as follows :-Later clayey gravel 3 ft., London clay (sandy below) 4 ft., band of flint pebbles 3 in., loamy basement bed 6 ft., Reading clay 5 ft. 6 in., Reading sand 14 ft., Reading pebbles (" bottom bed ") showing 4 ft. 6 in.; total 37 ft. 3 in. The thickness of the "bottom bed" here is probably 14~ ft., which gives a total thickness of 34 ft. for the Reading beds at Bushey. Crossing the line by the southern bridge, the party walked by the footpath parallel with the railway to the Oxhey Golf Course, where they were met by Colonel Fulton. Near the railway Reading sand is everywhere close to the surface, with a covering of surface wash of slightly clayey sand and pebbles. from 1 to 3 ft. thick. The sand was exposed at several newlymade bunkers. About 75 yards E. of Oxhey Warren a pit showed 9 ft. of pale-greenish sand with four or five beds of large and small flint pebbles. In the middle of the course, 550 yards a little S. of W. from Oxhey Warren, a pit 30 yards long showed 7 ft. of Reading sand, greenish streaked with brown, with a narrow bed of flint pebbles. This and the foregoing section were similar to sections seen on the excursion to the neighbouring Sandy Lodge Golf Course.* North of this pit and due west of Oxhey Warren is a narrow copse, extending E. and W. Alongside the greater part of this copse pale greenish Reading clay had been exposed in a shallow trench, but this could not be seen by the party. The junction of the Reading sand and clay cannot be far, possibly about 70 yards, west of the pit just referred to. The junction would extend round to the top of Big Wood, or a little above it; but nowhere could it be seen. Near the S.W. corner of Big Wood the bottom pebble-bed of the Reading series had been exposed to a depth of 6 ft.; but this had been covered, and only a heap of sand and of the smallest pebbles, which had been sifted out, could be seen. West of Big Wood, Reading sand was seen to be everywhere at or near the surface, with pebbles in places, and five shallow exposures were examined. At the northern end of a copse at Long Spring, IIO yards west of a chalk pit, a section showed 3 ft. of the-

* See

Proc, Geol, Assoc.,

\'01.

xxl, p. 477.

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282

EXCURSION TO BUSHEY, OXHEY, AND WATFORD HEATH.

bottom pebble-bed, with 2 ft. of surface wash of sand and pebbles. The top of the Chalk could be seen near at hand, a little lower than the pebble-bed, in an old disused pit. Also the top of the Chalk in the large pit was observed to be approximately level with the bottom of the bed of pebbles along the line of strike. There was no time to examine the Chalk; no fossils had been found j but the pit is probably in the Cor-anguimon Zone. On the high ground N.N.E. of Big Wood, near a pond, at .about 278 ft. O.D., was seen 4 ft. of Pleistocene gravel, mostly of flint, but quartz pebbles were common, and a few specimens of quartzite, sandstone, and clay ironstone were found. At the top of the high ground, N.E. of Big Wood, about 285 ft. O.D., a hole showed 4 ft. of slightly coarse brown sand, underneath I ft. of surface soil. Water was held up in the hole 4 ft. below the surface. No trace of the "basement bed" of the London day had been found. The shallow trench previously mentioned had been dug across the top of the high ground, and this showed the top of the hill to consist of a capping of sand. If the "basement bed" is entirely absent, the Reading clay here must be 10 or 12 ft. thick. On the proposal of Dr. Evans, seconded by Mr. A. Sutton, a vote of thanks was passed to the Directors of the Golf Club, and to Colonel Fulton, who accompanied the party over the course. Taking the road from Oxhey Warren .and a field-path, the party walked to Watford Heath, where tea was taken at the "Load of Hay." The usual vote of thanks to the Directors was passed. After tea a short walk was taken to Mr. H. W. Stone's brickfield, referred to by Mr. Whitaker on p. 254 of the Geology of London as the" Watford Heath Kiln." The section here showed pale Reading sand 16 ft. j basement bed of London clay (with thin band of flint pebbles at the bottom and a 3 in. band of pebbles at the top) 7 ft. 6 in. j sandy clay with" race" in places 5ft. j brown London clay IS ft. j total 43 ft. 6 in. An interesting feature here was the total absence of the Reading clay, the '" basement bed" being seen to rest immediately on the Reading sand. The writer quoted reports of visits to the pit on two previous occasions, viz., on 23rd June, 1870, when Mr. J. Hopkinson was Director, and on 13th April, 1872, when the Directors were Mr. Whitaker and Mr. Hopkinson. The partial .absence of the Reading clay was observed in 1872 j "the basement bed reposing in one part of the pit immediately on the mottled clay, and in another on the sand."* Traces of clay can now be found among the pebbles at the bottom of the basement bed. In the basement bed fragmentary fossils were observed j also several teeth of Lamna and one of Odontaspis (?) were found in the upper band of pebbles. * See" Record of Excursions," Geologist Association, pp. 153 and 156.

PROC. GEOL.

Assoc.,

VOL.

XXII.

PLATE

I'lt

'jJ"J

XLII.

T.II "oR ,

I · In".

BUSHEY CUTTING (LOOKING NORTH).

(a) Easement Bed of London Clay; (0) Reading Clay; (c) Reading Sand with bottom bed of pebbles showing below.

To face talie

282.

EXCURSION TO GUILDFORD, COlIPTON, AND GODALilIING.

283

,supplementary Note to previous Report, ante pp. 155 and 156. Before leaving Mr. Stone's pit, the writer referred again to the thickening of the Reading clay southward of the Bushey Cutting. A few days previously he had measured the Reading ,clay in the cutting near Sandpit Wood. Up the slope of the .cutting the clay measured 24 ft., and as the slope gil'es a thickl1eSS of 2 to I, the Reading clay is here 12 it. thick. The top .band of flint pebbles of the basement bed of the London clay runs out at the top of the cutting, on the west side, opposite the southern end of Sandpit Wood, between the fifth and sixth 'telegraph posts north of Little Oxhey Lane Bridge. REFERENCES. Geological Survey Map, London District (Drift), Sheet I. N.W. Fieldpath Map of the Watford District, Stanford. Price IS. and 25. 1854. PRESTWICH.-Qllart. yourn. Ceo!. Soc., vol. x, p. g1. 1889. WHITAKER, W.-" Geology of London." Ment. Geol. Survey, vol. i. 19o9. WOODWARD, H. B _ I I The Geology of the London District." Mem. Ceo!. Survey. Price 15. IglO. BARROW, G., and KInNER, H.-" Excursion to Sandy Lodge," Proc, Ceo!. Assoc.; vol. xxi, p. 477.

EXCURSION

TO

GUILDFORD,

COMPTON, AND

GODALMING. SATURDAY, JULY 1ST, 19I1.

Directors:

GEORGE

W. YOUNG, F.G.S., AND DOUGLAS LEIGHTON.

Excursion Secretary .. A. H.

WILLIAlIIS.

(Report 0)' THE DJRECTORS.)

ON arrival at Guildford the party, numbering 18, proceeded

along the towing-path through the gorge of the River Wey. The outcrop of the Chalk is very narrow, and St. Catherine's Hill, a steep river cliff of Folkestone or Upper Ferruginous Sands, was soon reached and ascended. Here a general description of the geology of the district was given.s The succession of the local subdivisions of the Lower Greensand in this district is very similar to that at S1. Martha's Hill (see p. 243), with the exception that the Bargate Stone is developed in a far greater degree. It is considerably thicker and extends much farther south than anywhere to the east, while its influence on the physical structure of this district is most remarkable. * See Report of Excursion to GuiJdford, 1897. Proc, Geel. Assoc., vol. xx. p. '74·