Page:Quarterly Journal of the Geological Society of London, vol. 26.djvu/545

 ft. in. ft. in. 4. Soft marly bed, with Ostrea Sowerbyi abundant 1 0

5. Compact marly limestone 2 3

6. Marly limestone, very soft, with Ostrea Sowerbyi, large Trigonia Moretoni, Modiola, and other Great-Oolite fossils 1 3

7. Dark-grey clay, with numerous Ostrea Sowerbyi 1 6

8. Ironstone band, with Ostrea Sowerbyi, Modiola imbricata, Pteroperna plana, Perna rugosa, var. quadrata, Natica (Euspira) pyramidata, &c. 0 9 to 1 0

9. Very variable sandy clay, sometimes more arenaceous than argillaceous, with vertical plant-markings 2 0 to 3 0

10. Orange sand, with nodules of ferruginous sandstone 3 0

11. Course of compact rock, occasionally calcareous 1 0 to 1 3

12. Compact rock, more ferruginous, and occasionally argillaceous 1 6

13. Ironstone beds — cellular ironstone, with ochreous, sandy, or green cores : towards the bottom the blocks are larger, and consist in the mass of green arenaceous material coated with iron-ore, as at Duston 10 0 to 12 0

The beds, 2 to 6 are limestone of the Great Oolite, and are probably equivalent to the lower beds of the last section ; but, lying near the surface instead of low down as in the limestone quarry, they have been altered by atmospheric action.

In the General Section, these beds would be referred to A ; 7 and 8 would, I think, represent B ; 9, with its plant-bed, C ; 10, and perhaps 11, D ; 12 may be considered perhaps debatable ground ; but 13 would doubtless be included in E.

The fossils obtained in these ferruginous beds are all of kinds collected from the Duston Ironstone ; but the zones of Astarte elegans, corals, and plants, seem here to be wanting.

The junction of the Ironstone beds with the Upper Lias is seen on the road-side at e e, well up on the hill between Blisworth and the railway station.

At Gayton, about a mile to the west, ironstone is also largely dug, the beds having very much of the character of, and yielding nearly the same fossils, as those of Blisworth, — very fine Pygoster semisulcatus, Cidaris Fowleri (confirmed by a fragmentary impression found by the late Dr. Berrill at the Northampton Asylum), very large casts of Ceromya bajociana and Isocardia (a hew species), Pleuromaria arinata, Astarte rhomhoidalis, Phil., and Hyboclypus ovalis, Wright, being noticeable. The overlying beds consist of the same series as in the other areas, but have been very much disturbed. The bottom bed of the limestone has yielded many large examples of Rhynchonella concinna.

[Note. — Since the reading of this Memoir before the Society, I have been favoured by a visit from Dr. Lycett, who examined the majority of the sections which I have described, and who obliged me with the following written opinion as to the geological equivalency of the white-limestone beds of the district : —

" The Great-Oolite beds of Kingsthorpe, Duston, and Blisworth appear to me to correspond, both in their lithological character and included fossils, with the beds of Forest Marble to the eastward of Minchinhampton. The Pholadomyoe, the Cardia, the Bulloe, the Corals are identical; and the association of these forms in the

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