| Anon. (2004). An earlier excursion, Bull Croydon Nat Hist Sci Soc, 124: 12. |
An earlier excursionOn Saturday, June 25 this summer Paul Sowan will be leading an excursion to Gilbert's pit SSSI (Site of Special Scientific Interest) which, as can be seen in the Annual Report for 2004, was the subject of advice* provided by Paul to the London Boroughs of Lewisham and Greenwich. Unlike members of the Society on August 19, 1892, anyone going to the pit this June will not have the benefit of the knowledge of Mr Gilbert, but they may care to read this description of an earlier visit by the Society. 'The Roman camp at Charlton, which was the next object made for, stands on a hill overlooking the Thames and the marshes bordering it on the Kent and Essex shores. The ramparts, much obliterated by the hand of Time, remain only on the W. and S. sides, the hill on which the N. and E. walls of the camp stood having been quarried away by a series of extensive excavations for the purpose of getting gravel, &c. An excavation on the N.W. side of the hill on which the camp stands shows the Thanet sands resting on the chalk. The junction of the two formations is marked by a bed called "bull-head" consisting of green-coated unworn flints, and ranging in thickness from 6 to 18 in., being thicker where it fills up inequalities in the surface of the adjacent chalk. (The same bed is to be met with in the chalk-pit at Park Hill, Croydon). The lowermost 7 ft. of the Thanet sand are locally called "black-foot" or "strong loam," and are valuable for foundry purposes, being well adapted for moulds for brass castings. The next 12 ft. above the "black-foot" consist of "mild loam," larger grained and less cohesive than that below, and better adapted for moulds for iron castings. These loams are exported for foundry use to parts of the world so distant as India and China. The upper part of the Thanet sand is a white sand. On the steep face on the E. side of the Camp hill this white sand is the lowest bed now exposed. Above it is a greenish sand, with rounded black flint pebbles, the lowermost of the Woolwich beds; above this again is a bed of strong reddish loam, also used for foundry purposes. Next above this come some 8 ft. of laminated grey clay, crowded with fossils, mostly fragmentary. Though individuals are abundant, the species represented are comparatively few. The following only were found :–Ostrea tenera and bellovacina, Cyrena cuneiformis and cordata, Melania inquinata, and a Cerithium. Above the shell-bed is a clay with few fossils, and above this again are the pebble-beds of the Oldhaven series, here some 14 ft. thick. Some fossils from the chalk were obtained from the workmen, among them being fish remains, Inoceramus sp., Terebratula semiglobosa, Ananchytes ovatus, Micraster cor-anguinum, and a spine of Cidaris. The party were indebted to Mr. Gilbert, of Charlton, by whom the pits are worked, for much valuable information, as well as for permission to visit them.'
* Extract from the 'Library' section of the Directors' Report for 2004: "It was especially pleasing to be able to assist the London Boroughs of Lewisham and Greenwich with evidence relating to the former use of Gilbert's Pit (Charlton), a geological SSSI, which enabled them to obtain a grant of £ 5,000 under the Aggregates Levy Sustainability Fund for the creation of new signs explaining the importance of the site." |
Last updated
March 22nd 2005 |