Page:Quarterly Journal of the Geological Society of London, vol. 26.djvu/537

1870.] SHARP NORTHAMPTONSHIRE OOLITES. 371 It will have been observed that in " The Roylands," bed no. 3, much wood, and slabs ripple-marked, have been found. These, I take it, indicate estuarine or littoral conditions during the period of deposition.

In the " "White Pendle," no. 5, we have a prominent example of the limestone and slaty beds which I have found to occur at different points over a considerable area in the same position in the general section of the district. The calcareous nature of these beds, and the slaty character of the so-called " Colleyweston Slate" (no. 5, b), and indeed of the Colleyweston Slate itself, I consider to be attributable to accidental and local causes, as are also, within more limited areas, the remarkable variations upon the same horizon in beds described in former sections ; but I cannot but think that the persistency of this limestone band over a considerable local area indicates a passage in time, an alteration in the depth of the aqueous bottom, and possibly a change to more marine conditions, which raise that band above the synchronous and patchy variations so frequent in the beds of D. This persistency, although sometimes the slate bed and sometimes both beds have been wanting, has induced me, for my own guidance, to adopt these beds as a mark of separation between what I consider to be the Middle Division (D) and the Lower Division (E) of the Northampton Sand.

At a distance of a few hundred yards from this Duston " Old " pit, is the " Old Slate-quarry Close." Here a stone-pit (v) was opened a few years since, which exposed some of the old workings, carried on, at some unknown distant time, for the obtaining of slate alone. The old process was that still sometimes adopted at Colleyweston, and called " foxing." Shafts were sunk, and the slate was extracted from beneath the overlying beds by means of adits.

The section of this pit has a less elevation than that of the " Old pit ; " and the beds are imperfect continuations of those of the latter, exhibiting traces of both natural and artificial disturbance. The characteristic and crowded zone of Astarte elegans of the " Rough Rag," no. 5, of the last section, is continued into this section. I have also found this zone in two other sections in the Duston area, presently to be described, severally a mile and a half and two miles from this point, and also at the Harlestone pits, at v', more than a mile to the north-east of Duston " Old " pit ; so that this Astarte-elegans zone extends over an area at least three miles in diameter in one direction.

I have to thank the proprietor of these two stone-pits (Mr. Samuel Golby) for information communicated by, and fossils received from him.

In a small pit temporarily opened at a short distance east of v, I obtained from the limestone-bed no. 5 a, a very perfect tooth of Megalosaurus.

About a mile south of the " Old " Duston pit (at w), upon the escarpment of the hill overlooking the wide valley, some four miles in breadth, traversed by the southern branch of the river Nen, and by the main line of the London and North-Western Railway, (in which