Excursion To Hatfield. June 28th, 1873 - Geologists' Association excursion
|From: A record of excursions made between 1860 and 1890. Edited by Thomas Vincent Holmes , F.G.S. and C. Davies Sherborn, F.G.S. London: Edward Stanford [For the Geologists’ Association], 1891. Source: Cornell University copy on the Internet Archive (Public domain work)|
Through little visited as a locality of geological interest, the neighbourhood of Hatfield presents sections both of the older and of the newer Tertiaries of considerable importance. Situated on the northern edge of the London Tertiary Basin, Hatfield is an advantageous point of departure for a geologist who wishes to trace the junction of the Secondary and Tertiary Beds. To enable the Members of the Association to traverse this line, and to inspect the principal section, the Marquis of Salisbury courteously threw open Hatfield Park.
On reaching the extreme eastern limits of Hatfield Park the party entered an extensive excavation, in which are seen all the beds occurring in this locality between the London Clay and the Chalk, which forms the bottom of the excavation, with the high level Post-Pliocene gravel capping the whole.
Mr. Whitaker, in "The Geology of the London Basin," p. 226, gives the following details of this section :
|Gravel composed of various sized pebbles of flints, white and pink quartz, quartz rock, and some other rocks, and subangular flints, in coarse whitish sand, in parts as much as||6|
|Stiff brown clay, more sandy towards the base||20|
|London Clay||Brown loam with green grains||about 7|
|Basement Bed||Thin bed of brown clay|
|Olive green and dull brown sand|
|Dull brown sand with green grains and perished shells|
|Brown loam with small nodules of stone and perished|
|Thin bed of flint pebbles, mostly small|
|Reading Beds||White and light-coloured sand, with layers of grey, laminated clay; at parts some very small pieces of ironstone, and here fr, and there a flint pebble; for the most part regularly bedded, but a little false bedding in the lower part|
|Bottom Bed—Flint pebbles and subangular flints; very dark green (almost black) outside, in sand; the upper part ironshot, the middle grey and greenish yellow, the base ironshot; greatest thickness||about 2|
|Chalk with flints. Junction even and with a dip about S.E.|
It will be noticed that the Thanet Sands are not present here, and that the beds immediately below the London Clay Basement Bed have the character of those near Reading rather than of those in the neighbourhood of Woolwich, while the mottled clay is entirely wanting. The sands overlying the Chalk might be mistaken for the Thanet Sands, but the thinning out of those deposits considerably to the south of this locality, and the evidence of other sections in the district, leave no room for doubt as to the age of these beds. A multitude of sand-martins find a home in the sands, which are quite honeycombed by these industrious excavators. The section having been explained, the party left the spot, and ascended to the higher level, where a brick-pit exposes a continuation of the section, and shows the High Level Gravels capping the London Clay, and thence proceeded, bya north-western route for about three miles, to a cutting on the Great Northern Railway, where a section nearly half a mile in length exposes the Middle Glacial Sands and Gravels, with a thin overlying sheet of Boulder Clay forming the subsoil of the land. The railway to Hatfield was then traversed, and the sections of the Glacial Beds along this part of the line were examined. On arriving at Hatfield the party took train for London.
[A second excursion to Hatfield was made on May 13th, 1876, the director being John Hopkinson. There is a brief report of this excursion in Proc. vol. iv. p. 518, Mr. Hopkinson referring the reader to the above account of the geology of the district. The following details, however, are from Mr. Hopkinson's report.]
Permission to see over Hatfield House, and to visit the Hatfield Park Kiln, had been kindly granted by the Marquis of Salisbury.
The house, which was first visited, is necessarily more of historical than geological interest. It is built on the site of the palace of Bishop Morton, which was erected about the end of the fifteenth century, and of which a fragment still remains; and on its site again, from the commencement of the twelfth century, an episcopal residence had existed. The present mansion was commenced in 1607, and the materials used in its construction by its builder and architect, Robert Cecil, Earl of Salisbury, consisted chiefly of Caen stone, with stone from Tattenhall, Worksop, and the Northamptonshire quarries, and bricks and flints from the old palace which had fallen into decay.
After spending a considerable time in the house and grounds, the party proceeded across the park to the brickfields, noticing on the way Queen Elizabeth's favourite oak, under which she was sitting when the news was brought to her that she was Queen of of England.
[Potter's Bar, Potterell's Park, and Hatfield were visited on April i9th, 1890, the Directors being Upfield Green and Dr. Morison. An excursion to Welwyn took place on May 15th, 1886, Director, John Hopkinson. A report, by the Director, appears in the Proceedings (vol. ix. p. 534).]