THE roads of south Durham and the Tees Valley are lined with excrement, and that is what makes them feel and look like home.

It is tempting to say that it makes them unique, because the shiney grey-blue of the scoria brick is certainly part of the character of this area.

But early in the last century, the excrement was exported around the world. Streets in Canada, the West Indies, Holland, the US, India and South America were lined with our leftovers.

Echo Memories has been trying to understand the bricks beneath our feet for some months now. With the help of Charles McNab, from Hurworth, near Darlington, we have probably come as far as we can ' unless you can take us further.

'scoria' comes from the Greek word meaning 'excrement or dung'. The Romans applied it to the hot dark lava wastefully tossed from the top of a volcano.

Then, about 140 years ago, industrialists on Teesside applied it to the hot waste found at the bottom of a blast furnace.

They would have called it slag if they were common; scoria made it sound more refined and scientific.

Whatever it was called, it was a problem. Producing one ton of iron produced one ton of slag.

As the furnaces of Cleveland were producing 2.5 million tons of pig iron a year towards the end of the 19th Century, there was an awful lot of slag about.

At first, it was tipped onto the boggy, salty marshlands around Middlesbrough to raise them up. When these were filled, the ironmasters paid the Tees Conservancy Commissioners 4d a ton to take the slag away. It was used to build 20 miles of riverside walls.

The ironmasters did not want to pay to have their rubbish removed. They wanted to profit from it.

Someone had a brainwave.

If you fired a jet of air through liquid slag, it dried into long, thin strands of slag wool. Slag wool had good insulating properties.

Production began at the Tees Iron Works in 1877.

Joseph Woodward's idea was much better. In November 1872, the Darlington man formed the Tees Scoriae Brick Company to turn slag from the Clay Lane Blast Furnace, in Eston, Middlesbrough, into the shiney-blue bricks that now line our lanes.

It was a complex process.

The molten slag was tapped from the bottom of the blast furnaces and transported in bogies down a railway to Mr Woodward's patent revolving table.

The slag was tipped out of the bogies into brick-shaped moulds on Mr Woodward's table. As the table rotated, the slag cooled. After two minutes, the slag was still red hot, but it had set. At the vital moment, the turning motion of the table tipped the brick out of the mould and onto a conveyor belt which carried it into an oven, heated by the furnace.

In this 'annealing kiln', the bricks were cooked for three days 'after which they are perfect, cool, solid and hard, and ready for use', according to the Colliery Guardian newspaper of 1873.

Stockton bought the first consignment and discovered the bricks to be just the job.

The first roads were mud, which was too muddy. Then they were cobbles, which were too bumpy. Then they were laid with setts ' lumps of stone hewn by hand into regular shape ' which could be brittle as the weight of wagons increased.

Scoria bricks were very hard to break. They were very durable, even when being run over by the metallined wheels of the heavy carts. They were completely waterproof ' Darlington laid them in its disease-ridden yards so they could be sluiced out. They were even chemical-proof ' Billingham laid them in ICI's drainage channels. Being from the same mould, scoria bricks were identical in size, and so could easily be laid flat (they were laid on a 6in bed of sand and then compressed down by men with heavy wooden rammers).

And they were cheap and plentiful.

Soon it was not just south Durham towns that wanted scoria bricks. In 1912, 62,881 tons of scoria bricks were exported from Teesmouth.

Thirty-seven per cent of these went to Canada, and 36 per cent to the West Indies.

Smaller quantities went to Holland (Rotterdam was an early customer), Belgium, the US, South America and Africa.

As the average scoria brick weighs 13lbs (or 5.9kg), this means that in 1912 alone, nearly 11 million bricks were exported. This excrement was clearly big business!

But it was a business that was killed by the motor car.

The posh passengers in cars wanted a smoother ride than scoria bricks could provide.

The stripping of the scoriae started in the Thirties, to be replaced by tarmac.

The Tees Scorriae Brick Company went bankrupt in 1966 and was formally wound up in 1972.

Still, though, they remain in our back lanes and gutters, each one proof that there is a fascinating history THE Tees Scorriae Brick Company appears to have produced 12 different types of scoria brick. The most common are either plain bricks or the double bricks, which have a dividing line down the middle.

There were also mosaiclike bricks where the surface was divided into eight.

Then came the fancy stuff.

Some were covered in small diamonds, while ' best of all ' there was a double hexagon design which cleverly locked together with its neighbour.

Finally, there were a couple of designs with writing on. One bore the legend: 'Tees Scoriae Brick Co patent', and another (which we have never seen) said 'Woodward patent'.

Because this is the saddest column in the paper, we would love to know if you've got any unusual scoriae in your street.

SO who was this Joseph Woodward, of Darlington, who proved that where there's slag there's brass'

He's an elusive character.

In 1868, the only Joseph Woodward living in Darlington ran a boot, shoe and hosiery warehouse in Priestgate. In 1873, the only Joseph Woodward was a brewer living in North Terrace, which still stands on Northgate. So did the slag king try several trades before finding salvation in scoria'

The first chairman of his company was Thomas Greener, who lived in Benton Lodge, Woodlands Road, in Darlington. In 1873, Greener was listed simply as a 'gentleman' of independent means, but in 1876 the grubby source of those means was revealed.

He was described as a coal, coke and iron merchant and 'sole patentee of Greener and Ellis' patent for oxide dry bottoms'.

This sounds as if he had invented an early disposable nappy but, in fact, the dry bottoms refer to those of mill furnaces.

The office was in Station Street, Bank Top, Darlington ' an address shared by the scoria brick company. This street seems to have disappeared in about 1885 when the mainline station was built on top of the wooden shed that had served as a waiting room.

Both Woodward and Greener had disappeared from Darlington by this time ' hopefully, they were somewhere counting the fortune they'd made out of slag.