Excursion to Swanscombe, June 7th, 1913 - Geologists' Association excursion

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Geologists' Association Circular No. 156. Session 1912-1913. p.4-5

Excursion to Swanscombe. Saturday, June 7th, 1913 (Transcription from: GA Circular No. 156. Session 1912-1913. p.4-5)

DIRECTORS: DEWEY, F.G.S., and REGINALD A. SMITH, F.S.A.

EXCURSION SECRETARY: E. C. MARTIN, "Hatfield," Lower Park Road, Loughton, Essex.

Leave Cannon Street 1.16 p.m., arrive Greenhithe 2.20 p.m. To obtain cheap tickets, 2s. 6d. return, meet. the Excursion Secretary under the clock not later than 11.0 p.m.

Walk to Globe Pit ; examine section of gravel filling channels in Thanet and and overlain locally by brick-earth. There is no stratification ; the deposits apparently being derived from tumultuous waters. Palaeoliths referable to St. Acheul II type, with white patina and reversed S twist, have been found in the brick-earth, along with others of Le Moustier character. These deposits lie on Thanet Sand and Chalk at about 100 feet above O.D.

Proceed to Barnfield Pit (Milton Street) to study, by kind permission of the Associated Portland Cement Manufacturers, the well-stratified gravels and barns explored recently by the British Museum and Geological Survey. The sequence is in descending order.

Upper Gravel

Upper Loam

Middle Gravel and current bedded sand

Lower Loam

Lower Gravel

——————

Thanet Sand—Chalk

The Lower Gravel is coarse and contains mammalian remains, chiefly Elephas aniiquus; but no true palaeoliths. Worked flakes are abundant, and cylindrical flints fashioned into points and chisel edges have been met with. They resemble the Strépy type of Dr. Rutot's classification.

The Middle Gravel is most productive of palLeotiths. These occur throughout the gravel hut most commonly in its lowest part. An evolution of type can be traced among the implements. They are for the most part Chelles type, but some examples from the higher beds of the gravel are early St. Acheul in character. It is doubtful if the Tipper Gravel is a river deposit it contains white patinated implements of St. Acheul period.

The base of these deposits maintains an average height of 90 feet above O.D., and the terrace has in consequence been termed the 100-foot terrace.

Proceed to Southfleet Pit (Baker's Hole). This pit is in a valley (of the Ebbsfleet) cut through the gravels of the 100-foot terrace for a depth of fifty feet, and itself partly mulled with Chalk rubble, loam and sand in gnarled and irregular masses. This rubble is the "Coombe Rock" and contains abundant remains of Elephas primigenius, Rhinoceros tichorhinus and other forms. Beneath it a palaeolithic floor was discovered whence many thousands of implements have been collected. These all are referable to the Le Moustier period (Levallois flakes), and lie as they were left by their manufacturers, under the sludge stream which overwhelmed them. The 100-foot terrace forms a characteristic feature on both sides of the Ebbsfleet Valley, respectively at Swamcornbe and Northfleet.

Tea (1s.) at 5.30 at the Factory Club, Northfleet.

Return to town by 7.8 train from Northfleet, due Cannon Street 8.12.

Total walking distance about four miles.

Many sections are worth photographing.

REFERENCES.

1 inch Geological Survey Map, London, Sheet 4, colour printed.

1 inch Geological. Survey Map, Old Series, London, hand coloured.

1 inch Ordnance Map, New Series, Sheet 271, Dartford.

HINTON AND KENNARD.—Essex Naluralist, vol. xv, pp. 56–88

HINTON AND KENNARD.—Proc. Geol. Assoc., vol. xix, pp. 76–100, 1905.

POCOCK, T. I.—Mem. Geol. Surv., Summ. of Progress for 1902, pp. 199–207, 1903.

SMITH, R. A.—Archaeologia, lxii, 1911, p. 515.

WOODWARD, H. B. .—Mem. Geol. Surv., Geology of London, 1909.

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