Collyweston and Easton area:  In addition to this still being an active extraction area, the extraction of slate in this area has been extensive for some time. The Jurassic Rocks of Britain (1894) notes that slate had been quarried there for over three centuries, as well as in other places. The Geology of Rutland and Parts of Lincoln, Leicester, Huntingdon and Cambridge (1875) by Judd says that at the time of writing Collyweston was being extensively worked for slate, but that only a small working at Deene was working at the same time.

Burghley Park:  At the south end of Burghley Park there is a quarry shown on 19th century mapping adjacent to a road marked as Barnack Drift (now Green Drift). The location of the quarry, at the base of the limestone, and the associated place name would suggest a source of slate from both the quarry and an unidentified mine. Lockwood’s A treatise on metalliferous minerals and mining of 1881 refers to Burghley Park Ironstone Quarry with Collyweston slate on the top of the sequence before passing to sand and ironstone. This probably refers to this quarry marked on the mapping. This is also mentioned by Judd, and although it is referred to as an ironstone quarry it is unlikely that the slate would have been ignored during extraction.

Duddington:  The historical extraction of slate is mentioned in both the Jurassic Rocks of Britain and by Judd, the latter is more detailed and describes how a number of slate pits existed by the River Welland, however they were believed to have been abandoned after flooding from the river. The site of these pits is not visible on old mapping.

Dingley:  Judd mentions that a pit south of Dingley contained beds representative of Collyweston Slate where stone was extracted. This is not visible on the early mapping, however as with other locations there are interestingly shaped boundaries to small enclosures which may indicate the presence of unmarked mine entrances/drifts.

Wittering:  Although Judd discusses that Wittering Pendle flagstone had been considered the same as Collyweston Slate, he does point out there are some differences. However Howe in The Geology of Building Stones (1910) notes that Wittering Pendle flagstone comes from the same beds as the Collyweston Slate at Wittering, suggesting that both might have been extracted in the area. There are certainly areas of quarrying shown on historic mapping, but these are not identified as specifically for slate.

Wothorpe:  Judd suggests old pits are traceable between Wothorpe near Stamford and the west side of Collyweston. The southern half of this line would include the existing quarries around Collyweston and Easton but it would appear that the beds were previously extended further north, although Judd must have observed the evidence on the ground as they are not visible on old maps.

Medbourne:  The Jurassic Rocks of Britain (1894 ) notes that historically Collyweston Slate was extracted at Medbourn although nothing is visible on historic mapping.

Neville-Holt Hill:  Judd suggests that old pits existed at Neville-Holt Hill (east of Medbourne) no definite mines but several quarries of different types and pits are visible on historic mapping, however none are marked as slate extraction on the mapping in the beds that are at the horizon of the Collyweston Slate.

Kirby:  There are numerous references to slate quarrying at Kirby, including those in the Geology of Kettering (BGS 2005), as well as the Jurassic Rocks of Britain (1894) and by Judd (1875). The latter is typically the most detailed, describing the pits around Kirby as extensive and in the ownership of Lord Winchelsea. This is one location that does identify the extraction of slate on historic mapping as well as showing how extensive at least one quarry was.

Deene:  Mentioned in the Jurassic Rocks of Britain and by Judd, there were known workings in the Deene area. In fact at the time of Judd’s work the small pit near Deene Lodge, on the border of Long Mantle Wood, was the only slate extraction left outside of Collyweston and Easton. It is also noted that the slate was present at Deene Brickyard. The presence of the slate was further discussed in Special Reports on the Mineral Resources of Great Britain (1924) which notes that in the Deene Pit near Corby there are large bullions of Collyweston slate which retain the fissility found elsewhere but set in a matrix similar to the Estuarine beds.

Others locations:  As well as the quarries open in Collyweston parish, Judd remarks on a small pit open at the time of his writing between Deene and Rockingham. It is unclear where this location is as the pit he mentions at Deene Lodge is on the other side of Deene, and the Kirby works are substantial rather than small. A search along the road on old maps reveals no obvious workings.

Geological sections were the slate was observed elsewhere:  Apart from known places of extraction, Collyweston Slate or beds representative of Collyweston slate horizon, have been mentioned at a number of other places, confirming that it was considered as a particular named type of stone over a much broader area than Collyweston itself.

In the discussions on the general geological sequences, the slate has been identified at Rushton Park, Stamford bridge, Exton, Wakerley and between Ufford and Marholm. In 1940 the Proceedings of the Geologists Association (Volume 1) records that “palaeontological evidence for the occurrence of a representative of the Collyweston Slate was obtained in the Station Quarry, Ancaster”.

Thanks to Philip Jefferson for this.

© Philip Jefferson 2014

Judd 1875 Geology of Rutland and Parts of Lincoln, Leicester, Huntingdon and Cambridge

As next in importance to the building stones of the Lincolnshire Ochres we must notice the fissile rock (Collyweston slate) which, as we have already seen, is procured from the lowest beds of the formation and has been largely employed as a roofing material.

We have already noticed how the quarrying of this material has declined of late years owing to the comparatively greater lightness, cheapness, durability, and convenience of Welsh slates, now rendered, by the improved railway communication of the district, everywhere available.

The beauty of the Collyweston slate and the manner in which its colour harmonizes with that of the stone employed in the walls of many ecclesiastical edifices, prevents the total abandonment of the industry. and many Gothic, architects, and notably Sir Gilbert Scott among others, continue to employ the material in the construction of modern churches. Hence a number of quarries, all in the parish of Collyweston, still remain open. At the period of the Geological Survey of the districts as already mentioned, a little pit was still open between Deene and Rockingham, from which small quantities of slate were raised for local purposes.

The Collyweston Slates have been dug over a considerable area in Sheet 64, old pits being traceable from Wothorp near Stamford to the western side of Collyweston, a distance of more than three miles

At the first of these places they are said, by tradition, to have been met with much nearer the surface than in the present workings, and this statement is confirmed by the geological relations of the beds in this neighbourhood. The valuable fissile character of the beds is merely a local accident and in some directions the bed of stone has been followed and found to become non‑fissile and in consequence worthless for roofing purposes. There is only a single bed of stone (the lowest limestone of the series) which is used for making roofing slates. This varies greatly in thickness, being often not more than 6 inches thick, hut sometimes swelling out to 18 inches, and in rare cases to 3 feet; while, not infrequently, the bed is altogether absent and its place represented by sand. Rounded mamillated surfaces, like the pot‑lids of Stonesfield, abound in those beds.

The slates are worked either in open quarries or by drifts (locally called 'f'ox‑holes") carried for a great distance underground in which the men work by the light of candles The upper beds of rock are removed by means of blasting, but the slate, rock itself cannot be thus worked, for though the blocks of slate rock when first removed appear to be quite uninjured yet when weathered they are found to be completely shivered and consequently rapidly fall into fragments. The slate rock is therefore entirely worked by means of wedges and picks, which, on account of the confined spaces in which they have to be used, are made single sided. The quarrying of the rock is facilitated by the very marked jointing of the beds, a set of master joints traversing the rocks with a strike 40° W. of N. (magnetic) while another set of joints less pronounced intersect the beds locally at right angles.

During the spring of the year the water in the pits rises so rapidly that it is impossible to get the slates out. The slates are usually dug during about six or eight weeks in December and January. The blocks of stone are laid out on the grass, preferably in a horizontal position. It is necessary that the water of the quarry shall not evaporate before the blocks are frosted and they are constantly kept watered, if necessary, until as late as March. The weather most favourable to the production of the slates is a rapid succession of sharp frosts and thaws. If the blocks are once allowed to become dry they lose their fissile qualities, and are said to be "stocked." Such blacks are broken up for road‑metal, for which they afford a very good material. The limestone beds above the slate rock are burnt for lime.

The slates are cleaved at any time after they are frosted. Three kinds of tools are used by the Collyweston slaters. The cliving hammer, a heavy hammer with broad chisel‑edge for splitting up the frosted blocks. The batting hammer or dressing hammer, a lighter tool for trimming the surfaces of the slates and chipping them to the required form and size. The bill and helve the former consisting of an old file sharpened and inserted into the latter in a very primitive manner. This tool is used for making the holes in the slates for the passage of the wooden pegs, by means of which the slates are fastened to the rafters of the roof. These holes are made by resting the slate on the batting hammer and cutting the hole with the bill.

The slates are sold by the thousand, which is a stack usually containing about 700 slates of various sizes, the larger ones being placed on the outside of the stack. The slates when sold on the spot fetch from 23s. to 45s per thousand. Many of the Collyweston slaters accept contracts for slating and go to various parts of England for the purpose of executing their contracts.

The land at Collyweston is generally hold by slaters by copyhold, the slaters paying 6s 8d a “pit” to the lord of the manor (a “pit” is 16 square yards) with an extra charge of 6d per pit to the measurer. A few workings are rented of the lord of the manor, ilia slaters paying 30s per pit with an additional 1s 0d. for the measurer. These payments are made every year at the annual slaters' feast' held in January.

The manner in which the slates are placed on the roof is as follows:‑ The largest are laid on nearest the wall plate, and the size of the slates is made gradually to diminish in approaching the ridge. The ridge itself is covered by tiles of a yellowish white tint, made at Whittlesea, and harmonising well in colour with the slates themselves. The larger slates are, in the ordinary way, fixed to the rafters of the roof by means of wooden pegs driven through a hole in the upper half of each slate. But roofs are often covered with small slates which are fixed by mortar.

The Slate of this County is found either in thicker Strata, which being sprinkled with Water and exposed to Frosts, do readily cleave into such thin and eaven Plates as are fit for covering the Roofs of Houses: Or in thinner Strata which as they come out of the Earth are immediately fit for that use, without the Preparation above-mentioned.

..For the other sort, Colly-Weston is of great and ancient Fame.

..The Lordship of Colly-Weston has afforded, and is still capable of affording, a great Quantity of Slatestone. They dig the like Slatestone in good plenty at Easton, and might do the same at Dudington ... So that this part of the County is plentifully stock'd with it; so plentifully, that even the meanest Houses of the Towns and villages hereabouts are slated. A safe, strong, and durable Covering it is, and so white and fine, when new especially, that in a bright Day it very pleasingly affects the Eye of a Traveller that has one of the Towns thus slated in his View.

...that of Collyweston, as also that of Kirby, a place affording abundance of excellent Slate, do cleave into thinner Plates than that of Easton. The thinness of the Slate is a valuable Property in this Respect, that it is less burdensome to the Roof that it is laid upon."

J.Morton 1712, The Natural History of Northamptonshire with some account of the antiquities. To which is annex'd a transcript of Doomsday-Book, so far as it relates to that county,  London, R. Knaplock and R. Wilkin 109