England 02: Dunstonburgh 1

Image Commentary

Perhaps one of the most outstanding examples anywhere in the world of the close relationship between man, the landscape and man's enterprising use of natural resources, is the example of the Whin Sill in northern England.

Geologically, the Whin Sill is best described as an exhumed intrusive igneous body. What this means is that a large body of molten rock called Diorite, deep in the subsurface, was able to find a zone of weakness in the crust and flow into it, probably as a red-hot mass of plastic lava, creeping its way into the country rock, forcing it apart and forming a long, continuous, almost horizontal mass that is different to the country rocks both above and below it. With eons of geological time, some uplift of the area and erosion of rocks that previously formed a roof cover, the country rocks and the invading intrusive rocks together were exhumed at the surface. But because the invading rock is harder than the country rock, it resisted erosion longer, and thereby become a hill forming outcrop, a particularly long outcrop that extends more than half way across the narrowest part of northern England.

The first to recognize the enormous strategic importance of this long stretch of hill forming Diorite rock were the Romans. Their occupation of the British Isles ground to a halt at the foothill entrance to Scottish territory, where they were held back by Celtic tribes who occupied the Scottish borderlands. Emporer Hadrian ordered the construction of what became known as Hadrian's Wall (see Image E14), a continuous fortification built atop the Whin Sill and extending from west to east coasts, intended to keep out the troublesome would-be insurgents. It did in fact workvery well for the Romans and represented the very northern extent of their realm.

After the Romans departed the British Isles, the "Dark Ages" commenced. Perhaps one of the most romanticised periods of British history, a time of misty legends, Arthurian tales of chivalry and wizardry, but that in reality were probably some of the harshest and cruelest. Towards the end of these times, warring factions (Normans, Danes, Saxons and more) competed intensely for control of kingdoms and territory and it was during these times that strongly fortified castles were built in support of their campaigns. Invariably good castle design called for every bit of help from the lie of the land and the strength of the building stone it could provide. Here at Dunstonburgh (Northumberland County) is one such exemplar. Sited at the point where the Whin Sill meets the North Sea shoreline, the location provided natural protection on almost all sides and a commandingly elevated viewpoint.

The architects and builders of both Hadrian's Wall and Dunstonburgh Castle made maximum use of rock quarried from the Sill itself. Diorite is a hard rock that today is still used heavily in laying the foundations of many roadways. The reason is simple, an igneous rock born of lava buried deep in the heart of the crust, is a hard, tough and heavy material, ideal for resisting unwelcome advances.