Excursion to Aylesbury, Hartwell and Stone. Saturday, July 27th, 1912 - Geologists' Association excursion

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Geologists' Association Circular No. 146. Session 1911–1912. p.6-8

Excursion to Aylesbury, Hartwell and Stone. Saturday, July 27th, 1912. (Transcription from GA Circular )

DIRECTOR: A. MORLEY DAVIES, D.Sc., F.G.S.

EXCURSION SECRETARY: DOUGLAS LEIGHTON, 108, St. Julian's Farm Road, West Norwood, S.E.

Leave Marylebone Tro, arrive Aylesbury 2.27.

Take special half-day return tickets at the booking office, price 3s.

Walk to Locke's Pit, Hartwell (1 mile), tire famous locality for the Hartwell City. Olcostephanus pallasianus, Trigonia voltzi, Astarte hartwellensis, Astarte mysis (?) and other fossils may be found; and possibly the overlying lydite-bed may be seen

Walk on to the Bugle Pit (1 mile). This famous pit is bow no longer worked and this may possibly be the last opportunity for seeing the section, in which Lower and probably Middle Purbeck Beds, with a marked "wash-out" rest upon Portland Stone with Perisphinctes boloniensis.

Walk on (1 mile) to the Windmill Pit, Stone, where the false-bedded unfossiliferous Aptian Sands are well shown, and where a good view of the Thame Valley is seen.

Tea at the Bugle Inn, Hartwell. Plain tea 10d., with eggs 1s.

The return walk may be made, if time permits, through-Hartwell Park, past the Egyptian Spring-(at junction of Portland Sand and Hartwell Clay).

Total walking distance under 6 miles.

Return train Aylesbury 8.0, arrive Baker Street 9.28.

REFERENCES.

Geological Survey Map, 1-in. scale. Sheet 46 S.W. Price 5s. 3d.

Geological Survey Index Map, Old Series, Sheer 12. New Series, Sheet 15. Price 2s. 6d,

Ordnance Survey Map, 1-in. scale. Sheet 237. Price 1s.

1880. BLAKE, J. F.—"Portland Rocks of England." Quart. Journ. Geol. Soc., vol. xxxvi, p. 189.

1895. WOODWARD, H. B.—"Jurassic Rocks of Britain." Mem. Geol. Surv, vol. v, pp. 220-229, 278-280.

1897. DAVIES, A. M., AND EMARY, P.--"Excursion to Ayleshmy, IIartwell and Stone." Proc. Geol. Assoc., vol. xv, pp. 90–97. Price 6d.

1899. DAVIES, A. M.—"Contributions to the Geology of the Thame Valley," Proc. Geol. Assoc., vol. xvi. Price 1s.

1909.DAVIES, A. M.—" Buckinghamshire" in Geology in the Field.

Other earlier references will be found in these papers.

Images

Excursion to Aylesbury, Hartwell and Stone, July 27th 1912

List of photographs

Excursion to Aylesbury, Hartwell and Stone, July 27th 1912

Page 129 P805582 Bugle Pit, Hartwell, in Middle or Upper and Lower Purbecks. Excursion to Aylesbury, Hartwell and Stone, July 27th 1912. Though of no great thickness the Purbeck Beds of both the Lower and the Middle or Upper division are here shown. The Middle and Upper stages being characterized by the Ostracod 'Cypridea punctata'.
Page 129 P805583 Bugle Pit, Hartwell, in Middle or Upper and Lower Purbecks. Excursion to Aylesbury, Hartwell and Stone, July 27th 1912. Though of no great thickness the Purbeck Beds of both the Lower and the Middle or Upper division are here shown. The Middle and Upper stages being characterized by the Ostracod 'Cypridea punctata'.
Page 129 P805584 Bugle Pit, Hartwell, in Middle or Upper and Lower Purbecks. Excursion to Aylesbury, Hartwell and Stone, July 27th 1912. The Upper Limestone of the Portlandian include several beds of creamy blue hearted limestone with Natica ceres and above this a bed of 'Roach' full of casts of Trigonia and other fossils. Added note: Hard limestone with Trigonia casts; Calcareous sandy bed; Pendle (hard fissile small); Lower Purbeck; Upper or Middle Purbeck.[Bottom to top.].
Page 129 P805585 Bugle Pit, Hartwell, in Middle or Upper and Lower Purbecks. Excursion to Aylesbury, Hartwell and Stone, July 27th 1912. The most well known fossil from this pit is the large Ammonite (Perisphinctes boloniensis) which is frequently seen built into the walls of Hartwell Park and other buildings as ornament. Added note: Pendle of Upper Portland, Ammonites boloniensis; Lower Purbeck; Middle or Upper Purbeck; Stony clay. [Bottom to top.].
Page 131 P805586 Locke's Brick Pit at Hartwell. Excursion to Aylesbury, Hartwell and Stone, July 27th 1912. This Hartwell Clay is not separated from the Kimmeridge Clay on the map but was probably at a higher horizon than any part of the clay of Kimmeridge cliffs. It differs from it however in being not at all shaly but sandy and glauconitic.
Page 131 P805587 Locke's Brick Pit at Hartwell. Excursion to Aylesbury, Hartwell and Stone, July 27th 1912. This Hartwell Clay is not separated from the Kimmeridge Clay on the map but was probably at a higher horizon than any part of the clay of Kimmeridge cliffs. It differs from it however in being not at all shaly but sandy and glauconitic.
Page 131 P805588 Specimens built in wall of Hartwell Park. These concretions called 'Bowel Stones' are formed of a hard siliceous material in the lower or brown Ferruginous sand of the Upper Greensand. Excursion to Aylesbury, Hartwell and Stone, July 27th 1912.
Page 133 P805589 Aptian Sands at Windmill Pit, Stone (Lower Greensand). Excursion to Aylesbury, Hartwell and Stone, July 27th 1912. In this pit is seen a bed of white sand 9 feet in thickness and beautifully false bedded with bands of pebbles, carbonaceous sands and concretions. Above them with an apparent unconformity due to contemporaneous erosion is a bed of clay 5 to 6 feet thick with ironstone bands near the base. These sands have been bleached by the action of organic acids arising from the decomposition of vegetable matter which have run out the iron and other soluble substances leaving a nearly pure silica suitable for glassmaking.
Page 133 P805590 Aptian Sands at Windmill Pit, Stone (Lower Greensand). Excursion to Aylesbury, Hartwell and Stone, July 27th 1912. In this pit is seen a bed of white sand 9 feet in thickness and beautifully false bedded with bands of pebbles, carbonaceous sands and concretions. Above them with an apparent unconformity due to contemporaneous erosion is a bed of clay 5 to 6 feet thick with ironstone bands near the base. These sands have been bleached by the action of organic acids arising from the decomposition of vegetable matter which have run out the iron and other soluble substances leaving a nearly pure silica suitable for glassmaking.
Page 133 P805591 Aptian Sands at Windmill Pit, Stone (Lower Greensand). Excursion to Aylesbury, Hartwell and Stone, July 27th 1912. In this pit is seen a bed of white sand 9 feet in thickness and beautifully false bedded with bands of pebbles, carbonaceous sands and concretions. Above them with an apparent unconformity due to contemporaneous erosion is a bed of clay 5 to 6 feet thick with ironstone bands near the base. These sands have been bleached by the action of organic acids arising from the decomposition of vegetable matter which have run out the iron and other soluble substances leaving a nearly pure silica suitable for glassmaking.
Page 133 P805592 View of the Thame Valley at the foot of the Chiltern Escarpment from Windmill Pit, Stone. Excursion to Aylesbury, Hartwell and Stone, July 27th 1912.
Page 135 P805593 Fossils from the Hartwell Clay. [Printed illustration.]. Excursion to Aylesbury, Hartwell and Stone, July 27th 1912.