Excursion to Harefield. Saturday, April 26th, 1913 - Geologists' Association excursion

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Geologists' Association Circular No. 154. Session 1912-1913. p.6-7.[edit]

Excursion to Harefield. Saturday, April 26th, 1913. (Transcription from: GA Circular No. 154. Session 1912-1913. p.6-7)[edit]

DIRECTORS: WHITAKER, B.A., F.R.S., F.G.S., and R. F. DE SALIS, F.G.S.

EXCURSION SECRETARY: T. W. READER, 17, Gloucester Road, Finsbury Park, N.

Leave Marylebone (G.C.R.) 1.55, arrive Denham 2:20 p.m. Take ordinary day excursion tickets to Denham, 1s. 1d. each.

The first section to be visited is that of the great pit, of the British Portland Cement Company at Harefield, This, starting in London Clay at the top, shows the loamy basement-bed of that formation, with broken shells ; then the mottled clays and sands of the Reading Beds, and beneath these the Upper Chalk with flints.

The junction of the Reading Beds and the Chalk is even, init. the top of the latter to a depth of more than a foot is riddled with small tubular borings, filled with green sand from above.

The Chalk belongs to the Micraster cor-anguinum-zone, as far as is known ; it issuggested that some of the more agile of the party should try to find a higher zone. Many species of fossils have been recorded from the Chalk of Harefield.

All the clays and the chalk of this pit are used in the making of cement, and bricks are also made from the Tertiary beds. The artificial making of flint pebbles in the pug-mills can be studied at the works. The process of cement-making will be explained by the manager, Mr. Downes.

The party will then go on to another large pit, northward, now in the hands of the Gelatinous White Cali, whose manager, Mr. Grivot, will explain the process of making the distemper. Whitening is also made. The section here is notahle as being. probably the best illustration we have of the formation of gravel-pipes in the chalk, many of those to be seen being very large, and some reaching down from top to bottom of the pit. Photographers, please note. The wash of gravel down a slope is also shown, and some of the difficulties of gravel-mapping are in evidence.

Tea at Challis's Restaurant, Harefield, price 9d. each, with eggs, 1s. each, after which walk back to Denham Station. Return train 8.5, arrive Marylebone 8.40.

Total walking distance 6 miles.

REFERENCES.

1 inch Geol. Survey Map, London, Sheet I, or the older map Sheet 7.

1889. WHITAKER, W.—"Geology of London, etc." Mem. Geol. Surv., vol. i.

1899. "Excursion to Harefield," Proc. Geol. Assoc., vol. xvi, P. 244.

JUKES-BROWNE, A, J.—"The Cretaceous Rocks of Britain," vol. iii. Mem. Geol. Surv.

Images[edit]

Excursion to Harefield, April 26th 1913[edit]

List of photographs[edit]

Excursion to Harefield, April 26th 1913[edit]

Page 19 P804538 Woolwich and Reading Beds. Excursion to Harefield, April 26th 1913.
Page 19 P804539 Woolwich and Reading Beds. Excursion to Harefield, April 26th 1913.
Page 21 P804540 London Clay. Excursion to Harefield, April 26th 1913.
Page 21 P804541 Flint pebbles. Excursion to Harefield, April 26th 1913. Added notes: Natural sea-worn flint pebbles. Flint pebbles made in the pug mill in 24 hours. [Bottom to top.].
Page 23 P804542 Excursion to Harefield, April 26th 1913. [Two photographs combined to give continuous landscape view.].
Page 23 P804543 Pipes in Chalk. Excursion to Harefield, April 26th 1913.
Page 23 P804544 Pipes in Chalk. Excursion to Harefield, April 26th 1913. [Building.].
Page 25 P804545 Pipes in Chalk. Excursion to Harefield, April 26th 1913.
Page 25 P804546 Pipes in Chalk. Excursion to Harefield, April 26th 1913.
Page 25 P804547 Pipes in Chalk. Excursion to Harefield, April 26th 1913.
Page 25 P804548 Pipes in Chalk. Excursion to Harefield, April 26th 1913.