Wrong Rock II

I’ve just finished preparing a presentation I’m giving at the 15th European Meeting of Environmental and Engineering Geophysics of the Near Surface Geoscience Division of EAGE (or Near Surface 2009). I’m so used to talking for a micro-century (~50 minutes) in lectures, it is hard to discipline one’s self to a 15 minute slot.

But, before I head of to Dublin, there is just time for the latest instalment of “Wrong Rock“. Last Time I discussed a church that had a new extension being built in a rock type that didn’t match the original. I also noted that the disused quarry that had supplied the original building was less that a kilometre away and it would have been much better from both an aesthetic and ‘stone miles’ point of view if a way could have been found to re-open that quarry to supply the stone for the church. This week I have uncovered what I consider to be an even bigger crime against stone.

Another Staffordshire Church

Like most old churches it was originally built from the local rock, in this case the Lower Triassic Kidderminster Formation (in old nomenclature Bunter Pebble Beds) which as the old name suggests is a coarse, pebbly sandstone. Again, the original quarry is close by, less than 500 metres from the church. This time it isn’t the modern extension (which is round the back) that I’m railing against, but the repair work on the original. These repairs have been done with Triassic Hollington Stone (formerly Lower Keuper Sandstone) which I’ve discussed before. It might not look too bad from a distance, but close up it really clashes.

Repair work

What is worse, is the nature of the repair. Rather than being flush with the existing stones, the steps on the top of the replaced blocks will collect water and cause the old stone block above it to weather even faster. And this is on a Grade One Listed Building, “a building of outstanding architectural or historic interest”. Special permission is required for repairs and particular materials are usually specified (although churches with current worship do have some exemptions). How much better the repairs would have been if the local stone had been specified and the replacement stone fitted flush with the original.

Wrong Rock

I’d like to introduce the concept of ‘stone miles’. A bit like ‘food miles’, building stones are often transported great distances (in some cases halfway around the world) when local ones will do, often much better. David Williams from ‘Stories in Stone‘ recently posted about the slate used for the new cafĂ© at the top of Mt. Snowdon in Wales being made not of Welsh slate but of Portuguese. The problem is that British planning laws make quarrying difficult and expensive. Yesterday I came across an example of where this is having repercussions even on a small county scale.

Here is a lovely old church in the Staffordshire Moorlands having an extension built – can you spot the problem?
Moorlands Church

The main church is made of the local bedrock, the Rough Rock (Carboniferous, Upper Namurian [OK, Lower Bashkirian if you insist] in age). It is not hard to track down the original quarry that supplied the stone. It is only ~500 metres away, now overgrown but otherwise OK. This is what the Rough Rock looks like …
Rough Rock

The problem is the extension is being built from Hollington Mottled Stone. I’ve discussed the Hollington Stone before, it is a Lower Triassic sandstone and looks like this – spot the difference?
Hollington Stone

Now, I’m not criticising the church. They have used the most locally available currently quarried building stone, it even comes from the same county, but it is the wrong rock and it doesn’t match. When it weathers it will become a closer match in terms of colour, but in terms of grain size and texture it simply isn’t right.

The Rough Rock is no longer quarried in Staffordshire for building stone. It is quarried where it is less well cemented, for glass sand, but that is another story. It is a shame that planning laws are such that it is simply uneconomic to reopen the original quarry to take a limited amount of stone for a heritage project that will be a perfect match to the church stone.

Britain is rapidly loosing it’s geodiversity. In Staffordshire about 25 different rock types were locally quarried for buildings. We are now down to two, and one of those isn’t really suited to much beyond drystone walling repairs. It is very sad to see local historical heritage buildings being added to with the wrong rock simply because it is the closest available match going.