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Chadwell Spring, the original source of the New River. Excursion to Hertingfordbury and Hertford, March 20th 1909. BGS Image P805315.
Chadwell Spring, the original source of the New River. Excursion to Hertingfordbury and Hertford, March 20th 1909. BGS Image P805316.

Geologists' Association Circular No. 106 Session 1908–1909 p.2-3.[edit]

Excursion to Hertford Area. Saturday, March 20th, 1909. (Transcription from GA Circular No. 106 Session 1908–1909 p.2–3)[edit]

DIRECTOR : G. BARROW, F.G.S.

EXCURSION SECRETARY : A. C. YOUNG, 17, Vicar's Hill, Lewisham, S.E.

Leave King's Cross (G.N. Railway) at 1.15 ; arrive at Hertingfordbury at 2.11. (Change at Hatfield). To obtain Special Return Tickets to Hertford, price 2s. 6d., meet Excursion Secretary in. Local Booking Office not later than 1 p.m. Alight at Hertingfordbury.

On the north side of the Lea the party will visit the gravel pits close by, where an exceptionally fine section of Chalky Boulder Clay, resting on bedded Glacial Sands and Gravels, has been recently exposed. The exceptional thickness of both will be noted. The special feature of the thick mass of Boulder Clay is the peculiar abundance of fossils in the basal part of it. The occurrence of numerous fossils in the Hertford Boulder Clays has long been known, and a collection of them has been made and is preserved in the Museum in the High Street. At Hertingfordbury, in addition to being abundant the fossils are extremely well preserved ; in many cases Ammonites have their keels and the Belemnites the sharp points quite intact. The fossils range in age from Lower Lias to Chalk. Time allowed from station to leaving pit, one hour.

At 3.15 p.m. the party will drive nearly two miles to another pit on the south side of the Lea, where an additional bed is seen, an upper sand and gravel resting on the Boulder Clay now much thinner. It will be pointed out that this three-fold division of the drifts continues all along the south side of the Lea for some distance east of Hertford. The upper sands have a singularly even surface over a considerable area, and the "plateau-nature" of the ground covered by them in this part of the country at once catches the eye.

At 4.0 the party will drive four miles to Chadwell Spring, which, 300 years ago, was taken by an aqueduct to form the water supply of London. Its maximum flow is not known, but quite recently it has yielded 5,000,000 gallons a day. The water issues from a swallow-hole in the Chalk, the normal working of which is reversed; instead of the water sinking down into it, the water rises up through it.

At 4.45 the party will drive about one and a-half miles to see a small section of the Reading Beds under the drift. From this point a walk of half-a-mile or so will bring them to another large pit in drifts, showing the three-fold division of these deposits. The stones in the drift will be examined and the assistance in their determination by experts is invited.

The party will then walk about a mile to the "Salisbury Arms," Hertford, where tea will be provided at 6.30. Price of tea, plain, is., or with eggs, is. 3d. Cost of drive, 1s. 3d. each. Total walking distance about five miles.

At 8.20 the train leaves Hertford for King's Cross, arriving at 9.15.

Those wishing to attend are requested to send in their names to the Secretary, so that they may be included in the arrangements for the drive.

Photographers are requested to bring their cameras.

REFERENCES.

Old Series 1-inch Geological Maps, 46-47.

Topographical Map, New Series, 239.

Papers in Quart. Journ. Geol. Soc. by Prof. HUGHES and Prof. PRESTWICH and others deal with the gravels in these adjacent areas.

Papers bearing on this subject have been published from time to time in the Transactions of the Herts Natural Hist. Soc.

List of photographs[edit]

Excursion to Hertingfordbury and Hertford, March 20th 1909[edit]

Page 59 P805315 Chadwell Spring, the original source of the New River. Excursion to Hertingfordbury and Hertford, March 20th 1909.
Page 59 P805316 Chadwell Spring, the original source of the New River. Excursion to Hertingfordbury and Hertford, March 20th 1909.