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EXCURSION TO HITCHIN AND ARLESEY.

SATURDAY, MAY 5TH, 1900.

Director: WILLIAM HILL, F.G.S.

Excursion Secretary .. A. K. C OOMARA SWAMY, F.G.S.

(Report by THE DIRECTOR.)

THE party arrived at Arlesey (Three Counties Station) at a littlebefore three o'clock, and proceeded at once to the large Gault pitin Messrs. Beart and Co .'s br ickyard. On the eastern side of thispit a section was seen which included the lower 10 ft. of the ChalkMarl, the thin Cambridge Greensand, and the Gault. TheCambridge Greensand was only exposed for some 12 or 15 yards,the bed having been thoroughly worked out in this district for thecoprolites it contained, which in the heyday of agriculture were ingreat demand for making artificial manures. The few yards nowseen had been preserved by an old kiln, which it did not payto remove when the coprolites were dug.

The President pointed out that the bed was evidently a line oferosi on; though the base of the Greensand was sharply markedthe upper sur face of the Gault on which it rested was uneven. Itcontained two sets of fossils, one derived from the Gault, and theother indigenous to the bed itself; the latter more closelyrelated to th e Chalk than to the Gault fauna. The bed passed upgradually to the Chalk Marl, and was regarded as the base of theChalk. Members were able to obtain a good view of thisinteresting bed now so rarely seen; below it the large pit atthe brickworks exposed some 50 ft. of un fossiliferous Gault.

The quarry of the Arlesey Cement Works was next visited.The upper part of the Chalk Marl , together with the TotternhoeStone and some 10 or IS feet of the chalk above it were exposed.The Director pointed out that the Chalk Marl was here about70 feet thi ck; the bluish-grey marl seen at the base of this .quarrywas the upward continuation of the whiter marl above the Cam­bridge Greensand. There was a considerable difference in thetwo marls: that just above the Greensand contained only 26 percent. of argillaceous (insoluble) matter, while the bluish-grey marlcontained 46 per cent. It was seen that the bluish-grey marlpassed rapidly upward into a whiter and more calcareous deposit.The aspect of the Totternhoe Stone seen in the quarry was some'what different from that at Totternhoe. At Totternhoe there issome 30 feet of evenly grain ed stone, suitable for building purposes,while her e the stone consists of two beds of rath er rough andrugged sandy (shelly) chalk, together about 12 feet thick. Thebed forms the upper limit of the Chalk Marl, and above it is thezone of H olaster subglobosus.

But few fossils were found in this quarry during the visit of the

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EXCURSION TO HERTINGFORDBURY, BAYFORD, ETC. 447

Association, though in the experience of the Director it hadproved exceptionally interesting from a collector's point of view.

Leaving the quarry the party took the high ground, walkingalong a field-way in the direction of H itchin. F rom a command­ing position the Direct or drew attention to the fact that the wholeoutcrop of the Cretaceous series, from Lower Greensand to UpperChalk, was in view. The President remarked that the outcrop of theGault in this district is some miles wide, while in Surrey that out ­crop is less, and often very much less, than a mile wide, th is beingdue to the steeper dip of the beds in Surrey.

On gaining the high road the part y proceeded over Wilbury Hilltowards Hitchin , crossing the old " Icknield Way" at right angles,th e Director drawing attention to some facts of antiquarian interest.They then visited a small but very typical exposure of the Mel­bourn Rock and after a brisk walk arr ived at H itchin at 6.30 p.m.

After partaking tea the members separated, those who had notalready seen the freshwater depos it at the Folly, H itchin, joinedthe Director in a visit to this interesting section. It has alreadybeen described in the PROCEEDINGS,'!l' but since the last visit of theAssociation Mr. Clement Reid has investigated the bed, and theresults of his work are published in the Proc. R. Soc. , vol. lxi,p. 40 (1897), repr inted in Trans. Herts. Nat. Hist. Soc., vol. x,pt. i, pp. 14-22 (1898).

Other members visited some interesting gravel pits, or spenttheir time in the quaint old town of Hitchin. Joining again atthe station the party returned to town by the 8.24 p.m. train,having spent a most enjoyable afternoon.

REFERENC ES.

Ordnan ce S ur vey Map , New Series, Sheet 221.Geologi cal Survey Map, Sheet 46, N. E.

1875. J UKES-BROWNE, A. J.-" On the R elations of the Ca mbridge Gaultand Greensand ." Quart . Journ . Geol. Soc., vol. xxxi, p. 256.

1886. HI LL, W., and J UKES-BROWNE, A. J. - " The Melbourn Rock."Quart. J'ouI·n. Geol , Soc., vol. xl ii, p. 216.

1887. . " O n the Lower Part of the U pper Cretaceous Series inW est Suffolk an d No rfolk." Quart . J'ourn. Geoi. Soc., vol, xliii,P·544·

EXCURSION TO HERTINGFORDBURY, BAYFORD, ANDBRICKENDEN GREEN,

SATURDAY, MAY 19TH, 1900.Director : A. E. SALTER, B.Sc., F.G.S.

Excursion Secretary: A. K. COOMARA SWAMY, F .G.S.(Report 6y THE DIRECTOR.)

THE party arrived at Hertingfordbury Station (G.N.R.) about2.30 p.m., and immediately set off to visit two large pits showinggravel and clay rest ing upon Chalk. Owing to the presence of pipes

* Vol. xiv , pp, 415'419.PROC. GEOL. Assoc., VOL. X VI., PART 8, J ULY, 1900.]