The Solway Firth [estuary] lies near the western border between England and Scotland, but during the Middle Ages the border was disputed and some lands on either side were called "The Debatable Lands." Included in this borderland was Solway Moss, on the north of the Solway Firth [estuary] in Cumbria, England.Its inhabitants were small farmers who eked out a living in the windswept, damp land and who used the moss, a typical raised bog, as a source of summer pasture and peat for fuel. I must explain that in Northern English usage a moss is a bog.For example, a bog near where I live is called Black Moss.
Solway Moss has a grim history, for it was the site of a vicious battle in 1542 in which Henry the Eighth's forces won a victory over the seriously disorganised Scottish army. As usual, the aggressor was England's corpulent tyrant, who had invaded South West Scotland to coerce the Scottish king into accepting a reformation of the church on Henry's lines, which Scotland's Catholic king did not want to do, but the badly led Scottish defenders were driven away in disorder. Many Scots fleeing across the Moss were drowned in the hidden mires.
The bog had been growing since the end of the Ice Age twelve thousand years ago, but it had been shaped by human activity. The grazing of cattle had no effect on its structure, but peat digging did.The local people dug peat for fuel, and did so on the edges of the bog. They carted away the peat blocks, casually throwing the peat crumbs onto the ground, and these were trampled and compacted by footfall. This process went on for millenia, and slowly, without anyone noticing a thick wall of compacted peat began to develop around the bog. This growth of an inadvertent damn went on for untold time. But to make matters worse, as the damn grew so did the bog. Rather than spread out as it would do naturally it grew upwards.
Bog growth is caused by the fact that sphagnum moss takes carbon and oxygen from the air, but does not decay properly, turning into peat, which traps CO2. Deposits of this semi-decayed plant resource accumulate over time, making bogs quite deep. In fact raised bogs can be domed in the middle. By 1771 the firm wall of Solway Moss was entrapping a bog that was fifty feet higher than the surrounding land, a vast reserve of soggy peat waiting to burst.
Local people may have been aware of the danger, as bogs had slid before, though many would not have known of the large bog slide of Chat Moss near Manchester in South Lancashire in the seventeeth century, but they lived in hope and fear, trapped by poverty and unable to migrate to somewhere safer.Then in November 1771 came the deluge, a sustained period of heavy rain saturated the bog and soaked the damn, fatally weakening it. On November the Sixteenth the weakened damn gave way and millions of tons of peat began to slide slowly and inexorably towards the nearby River Esk, one of the rivers that flow into the Solway Firth