JUST AN OLD WALL!

Think about heritage and old buildings come to mind, nicely built, good looking and often with stories to tell.

But in Sunderland there is another major aspect of heritage – its geological setting.  Without its coal, and subsequent coal mining, there would have been no ship building, no port and no base for its current industrial and technical diversity.  Without the coal, what would the city be like now?

This heritage is reflected in rough stone walls built in the 18^th and 19^th centuries, walls that are unique to Sunderland and its surroundings. A pity then that the significance of these walls is largely ignored (by the Council and developers alike), to such an extent that their demolition is expected – after all they are just old walls that get in the way!

What’s so special about these walls? It’s the types of stone that goes into their building. The main components are local Coal Measures Sandstone, local Magnesian Limestone of Permian age, glacial erratic from the end of the Ice Age, and ships’ ballast brought to Sunderland by the coal trade. Let’s deal with each of these types in turn:-

• Coal Measures Sandstone – as well as coal, this sequence provided huge amounts of building stone, derived from the rivers that criss-crossed the coal forming swamps.  This is without doubt the principal building stone that was used in the North of England and many quarries were cut into the valley sides. Poorer quality material has ended up in old boundary walls across the region. Around the Tyne, it was the only material available for use.  Its appeal is that the blocks found in walls display a huge range of depositional structures that we can look at close to – cross bedding indicating river current flow, scours and grain-size variations galore, and even the odd carbonized plant fragment.
• Magnesian Limestone.  Some of this is exclusive to the Sunderland area, other types can be found in walls south past Seaham to Hartlepool. The latter consists of creamy brown relatively well bedded magnesian limestone, probably belonging to the Raisby Formation (the traditional Lower Magnesian Limestone of the north-east). Small cavities and clumps of calcite crystals may occur, but the rock as a whole is relatively uniform.  In contrast with this is the Concretionary Limestone Formation (part of the old Upper Magnesian Limestone) which can only be found in the Sunderland area. This is a remarkable rock, resulting from break-up and chemical alteration maybe just 55 million years ago, long after its deposition c 255 mya.  The changes have created an incredible range of structures within the rock mass of which the famous Cannon Ball Limestone is just one.  They are all concretions, widely differing in form, hence the formation name, but no terminology exists to describe the structures.  They have been likened to varieties of pasta, frost flowers, honey combs, and much more and have to be seen to be believed (Fig 1). Some look temptingly like fossils, but there is no connection to anything organic in origin. In fact the extent of the chemical and physical change that has affected the rock will have made it impossible for fossils to survive. The walls display these structures to perfection – much better than at outcrop, now rather limited thanks to the obliteration of old quarries by landfill and development. This is one reason why the fate of these old walls is of concern.  Soon it may be nearly impossible to see one of the world’s rarest rocks.
• Glacial Erratics.  During the last phase of glaciation to affect the region, the Devensian, just a few tens of thousands of years ago, ice overrode much of the area, moving from the west and the north. The ice carried pebbles and blocks of rock from its source and picked up more material along the way.  This was dumped on the ground surface when the ice melted.  Improving the ground for agriculture and other purposes led to these “field stones” being incorporated in the boundary walls of fields, track ways and yards. Thus we can see in some of the walls, blocks of Carboniferous Limestone from the Dales, Old Red Sandstone from near the Borders and dark blocks of “whinstone” from the west or the north.  Some of the Coal Measures Sandstone may have arrived this way too. (Fig 2)
• Ships’ Ballast.  Colliers approaching Sunderland’s port in the 18^th and 19^th centuries would arrive “in ballast”, that is part loaded with stone to ensure the ship stayed stable. Before loading with coal this ballast would have to be disposed of, usually right next to the shore. This was a resource just asking to be recycled, and fair quantities of the stone ended up in the walls near to the River Wear. The range of rock types still to be seen is impressive , with types of granite, finer grained igneous rocks and  schists being most numerous and obvious. (Fig 3)  But there is importantly a historical element to this, (both social and economic).  By recognising the rock types, you can guess where the trade come from e.g. ballast of igneous and metamorphic origin probably was shipped over from Scandinavia while pieces of flint and the occasional lump of chalk most likely came from the English south coast.

To Sum Up:-  These old walls provide a magnificent show case of Sunderland’s geology,  containing blocks of what must be one of the World’s rarest rock types.  As well as this they give an unusual snapshot of the area’s historic coal trade, covering overseas destinations as well as ports in the UK.  Surely this makes them a priceless part of our heritage? Apparently not!

The Threats – to the best of my knowledge only one of these walls in the city has any protection, and that is the listed mid 18^th C wall on the east side of Green Terrace.  If anybody knows of any other walls given some protection, I would be delighted to hear from him/her.  But should this be the case then the majority of surviving walls are at risk to development.  There are two types of threat to the walls, a) demolition and b) “stabilization”.

Demolition – all too easy, and a case of out of sight, out of mind – but not to everybody, be warned!  If a wall had to be removed, i.e. there was absolutely no way it could be incorporated in the planned development, then surely the stone could be stockpiled – preserved for future use. How about a new feature wall in Mowbray Park, next to Building Hill which was once a source of the Concretionary Limestone?  Preservation as a feature at

its original site though should not be too much of a challenge to today’s planners!   Demolition though is ongoing: last year a wall at the west end of the Vaux site was demolished – it wasn’t in the way, a path still runs alongside its site - but it had to go to suit somebody’s tidy mind. More walling was demolished when the Cottam’s brushworks was bulldozed, at Sheepfolds.  This site still hosts some of the most interesting walling in Sunderland, along the edge overlooking the Wear. How long will this survive, I wonder?

Stabilization and Preservation – These walls are old, and many do need some care and attention. The old mortar can loosen and blocks fall out (Fig 4), or the banks they support might cause them to bulge.  It’s encouraging that in some case it has been recognised that the walls are worth preserving in situ, but the manner of this work sometimes brings me close to despair.  Here are two examples:

a) St Peter’s Church, Monkwearmouth.  Some exciting developments are taking place at perhaps Sunderland’s most historic site.  One job involved stabilizing the old retaining wall at the east end of the church yard, a wall that contained a fascinating collection of ships’ ballast. (The old church site was one of the major dumping grounds for ballast at one time). Sadly though the repair involved removal of a large swathe of original stone work, replacing it with fresh stone brought in from outside.  It just doesn’t belong, and the “repair” stands out like a sore thumb (Fig 5).

b) Green Terrace.  A year or two back, part of the northern end of the listed wall was giving way and needed repair.  Although, not such a glaring example as St Peter’s, once again “new” stone was brought in and these stones were emplaced using more than liberal amounts of mortar, masking much of the structure.   Over use of mortar seems a standard repair procedure these days (e.g. Fig 6, from Burdon Road).  I wonder why – the original builders used far less, and the walls have lasted pretty well!

Conclusions.  With Sunderland hosting the Tall Ships Race in 2018, there is a need to preserve structures associated with the city’s past maritime heritage.  These walls tick that box, and added to that display a geological heritage and uniqueness that many a city would cherish.  The fact that these walls disappear I put down to a lack of awareness by both the Council and planners as to their real significance. They really are more than just some “old walls”!   I’m hoping that by writing this, and spreading the word, Sunderland’s public might make them take note.  Readers who don’t reside by the River Wear, might recognise a similar situation and potential threat, wherever you live.

If you have a minute to spare, then please get back to me with your comments and thoughts.