Solway Bog Burst background Arthuret

In November 1771, Solway Moss burst, and flowed over the surrounding area, destroying houses and livestock. The land has never recovered.

On the night of 16 November 1771, after what was said to have been the heaviest deluge for at least two hundred years, the raised peat bog known as the Solway Moss burst its banks and overflowed some 400 acres of the surrounding farmland, covering it to a depth of up to 15 ft. A slow-motion mud avalanche spread over some 400 acres of the surrounding area, overwhelming around a dozen farmsteads which had occupied the land between the Rivers Esk and Sark, formerly known as The Debatable Land, which at one time had been contested between England and Scotland. The area covered by the irruption never really recovered and in 1915 HM Factory Gretna, a munitions factory, was built there. It is now part of Central Ammunition Depot (CAD) Longtown.

Like other mosslands, also known as raised mires or bogs, Solway Moss had been growing almost since the end of the last Ice Age, and now stood perhaps 50 feet higher than the surrounding farmland. Beneath a living surface of sphagnum, bog cotton, heather and some small shrubs interspersed with pools of water, there existed layer upon layer of compressed rotted vegetation known as peat, many yards deep. In summer dry enough to graze cattle upon, in winter the moss was a treacherous quagmire, dangerous to man and beast alike. Indeed after the Battle of Solway Moss, fought between the English and Scots in November 1542, several hundred of the defeated Scots are believed to have drowned trying to flee across the moss. Even more dangerously, at times of exceptionally wet weather, the sodden peat could swell and swell until it burst. Bog bursts of this sort were rare, but not unknown in England: Pillng Moss near Lancaster had burst in 1744, while Chat Moss near Warrington had burst in the early sixteenth century – but the Solway Moss burst was the first to attract scientific enquiry – and media interest.

A report of the event, consisting of a letter from Mr John Walker to the Earl of Bute was read to the Royal Society on 13 Feb 1772 (he wrongly gives the date as December 1771), and appeared with a plan in Philosophical Transactions for January 1772. (Philosophical Transactions, vol 62, pp.123-127, January 1772)

However, there is also a very fine manuscript map of the event, showing much more detail, in the King George III Topographical collection at the British Library

John Ainslie (1745-1828) was a Scottish surveyor (ODNB). At this date he was still in his 20s, and working for Thomas Jefferys, “Geographer to King George III”, on a series of English county maps. Ainslie had surveyed Buckinghamshire 1766-68, and Yorkshire, 1767-70. Jefferys had also published a map of Westmorland in 1770 surveyed by himself, but had not at this date published his map of Cumberland. When that map appeared in 1774, attributed to Thos Donald, it appears to have incorporated this aspect of Ainslie’s work, noted as ‘Land Covered by the Moss 1771’. Although not a scale map, Ainslie’s work is a substantially finer and more detailed piece of work than the printed map in Philosophical Transactions– and may have been specially commissioned by Jefferys – or even the King. 

A copy of the Map, and a blog, can be viewed here: John Ainslie's Plan of Solway Moss

Photo and text by Bill Shannon (text based upon the British Library blog)