Time-travelling by train Carlisle to Newcastle - part 3

This the final part of this rail journey from close to the west coast of England to the east coast, starts in Hexham and finishes in Newcastle upon Tyne. On the way there's a little discussion about geological maps and their availability and accuracy. But mainly we'll be looking at the geology and landscape - the river deposits and the valley - the challenge such valley routes present to engineers and the coal that was is important to not only the economy of this line - but also to the invention of railways themselves. 

Transcript

SPEAKER_00 0:10

Series five, Episode four Time Travelling by Train Carl Allen to Newcastle The Final Part Part three Welcome back to Hexham Station on the Tyne Valley Line and the last episode of this journey. I couldn't do these podcasts or write the books many of them are based on without using BGS maps. That's British Geological Survey Maps. That's the organization I used to work for, and around thirty years ago, the geological field mapping job I used to do. Approximately four hundred one to fifty thousand scale maps, that's about one inch to one mile, cover England, Scotland and Wales. Each of those maps were produced by generalizing around twenty one to ten thousand scale detailed maps, which was the field survey scale. These surveys began in eighteen thirty five and they've continued since. Some bits of the country have been mapped several times. The rocks don't change, but the information we have about them does. New boreholes, road and rail cuttings, mines and quarries, and our understanding of the geology and all its processes improves too. The experience of the geological surveyor matters a great deal as well, so there may be complete coverage for all of Britain, built up over the decades and now available in both digital and paper format, but the fact is that the quality and accuracy of these maps vary with age and all those other factors. Geological maps are no more than the interpretation of available evidence. It's also true that about fifteen years ago BGS took decisions to reprioritise its budget and reduce the resources it devoted to field mapping and maintaining its geological map quality. The arguments for and against those decisions could be the subject of a quite contentious podcast, but they don't belong in one about the geology of the Titan Valley line. However, a key aspect is relevant to this episode, and here's why. Any of you who have ever looked at the BGS Hexham geological map, that's sheet number nineteen, will have noticed the lack of detail. You may have even noticed it doesn't fit very well with the four sheets which border it. The rocks don't match. If you're a keen geologist, you may have even discovered that the hexam map gets the geology wrong in places too. That's because this map is old, largely the product of an early eighteen eighties survey with a bit of revision here and there in the nineteen forties. Since then, there's been a couple of bits of piecemeal modern mapping. But to date, BGS have yet to incorporate that and produce an up to date and more accurate geological map of the Hexham area and make it publicly available. There's not likely to be a hard copy printed copy. It'll be digital, another BGS policy decision. I'm told the Hexham sheet is on the agenda, but it's yet to be done. So if you struggle to make sense of the rocks around Hexham and its official map, you now know why. Time to get back on the train. We are running along the south side of the valley. The Tyne floodplain stretches over a kilometre across. There's about twenty plus meters of sand and gravel, with a little bit of stony glacial clay beneath the surface of that floodplain. The valley carved by the ice sheet is deep and was infilled with glacial and then river sediments in the last twenty thousand years. Way back in July 1975, I remember logging a sand and gravel survey borehole being drilled beside the Egger chipboard factory. It went down twenty two meters, still in those recent sediments. We had to abandon it before we hit bedrock. But it did prove that there's plenty of sand and gravel in this valley, as the new quarry share shows there. The line continues along the edge of the valley through Corbridge Station. About a kilometer further on it passes a place called Farnley. This has been a problematic bit of the railway for a long time. There used to be a tunnel here, but structural, for that read geological issues, forced its closure, and it was bypassed using a cutting in nineteen sixty two. Then much more recently, in 2016, heavy rain and a cracked sewer caused landslips, in excess of seventy thousand tons of earth moved down the slope, blocking the rail line. The solution was some more heavy mechanised earth moving and a reshaping of the slope profile and its composition. Routing a rail line or road through soft sediments and steep ground, like here at Farnley, is fraught with problems. It's always the trade-off for maintaining a route that hugs the valley side at the foot of a slope and above the river floodplain, in what engineering geologists call incompetent materials, that's unconsolidated clay, sand and silt, with inherently variably poor natural drainage. We are past Riding Mill now, and by the time we reach Stocksfield the line has crossed into younger carboniferous rocks, known as the coal measures. The name is a clue. From now we will be in a series of rocks that contain many coal seams, and many of them have been mined, either by deep mining or open cast mining, that's strip mining in the US. These coals used to be the basis of the economy of the northeast of England. They have been mined since Roman times, but it was between the eighteenth and twentieth centuries that most of the mining took place. It's hard just to say how many coals were mined here. Coal seam geology gets complicated because the coals merge and split. Just think of the way swamps that they formed in must have changed over time. But there were around twenty to twenty five seams named and mined. The names are now part of history, remembered only by the dwindling number of miners and geologists, for whom there used to be an everyday vocabulary, the Hutton Seam, the Low Main Seam, the High Main, the Ruler and the Brockwell. They are almost as engaging as the names mining companies gave to their mineshafts Anshaft, Percy Pitt, William or John, and sometimes just A Pitt. The ground underneath South North Lumberland and Durham is a labyrinth of tunnels and mineshafts. Mine plans record many of these workings, but it's fair to say that many of the shallower seams were worked early before plans became mandatory, that was in 1872, and we just don't know precisely where all those underground voids are. We know which areas they're likely to be undermined, but not always the detailed position, until something subsides or collapses. It used to be the National Coard, and then British Coal, but today it's the coal authority that have the responsibility to keep all those mine plans in Britain and investigate old coal workings and the issues that the collapse and pollution cause. But back to the railway. After Stocksfield there's Pruder, but in between we pass Eltringham, famous for two things Cherryburn Cottage, birthplace of the master wood engraver artist and naturalist Thomas Buick, and perhaps less well known for a late upper Paleolithic flint blade, found in a field here, and the best evidence we have of the earliest presence of humans in the northeast after the last glaciation around eleven thousand years ago. Squeezed between the river Tyne and the rail line right after Pruder, is a wooden mound. A ridge really, almost one point five kilometres long, a hundred meters wide and twenty meters high. Where the vegetation and soil have been worn away, it's white. The ridge, known as the Spechels, that's the previous name of the local riverside, is man made. It's made of millions of tons of waste material from a factory in Prada, which produced ammonium sulfate for the explosives and fertilizer during World War II. It was turfed to disguise the ridge and the factory from the German bombers. The trees that grow on it came later. The ridge is made of calcium carbonate, the same composition as limestone and chalk, and so this is the only piece of chalk downland in Northumberland. The specules is a special habitat here in Northumberland. It hasn't exactly got a southern chalk grassland flora, but rather a mix of lime loving plant, including musk mallow, musk thistle, kidney vetch, wild marjoram, and traveller's joy. Shortly after Wylam, the tidal limit of the river Tyne, we passed George Stevenson's birthplace, a cottage on the north bank. It sits beside Wylam Wagonway, later to become the North Wylam Branch Line. It was used to transport coal from Wylam Collier, and the wagonway is said to have been Stevenson's inspiration for his railway inventions. We are soon in Bladen, another place that has links with coal and mining and the industries that that spawned. But walk down Bladen burned today, and such has been the regeneration of trees and vegetation, that despite the scattered relics of mines and mills, it's hard to believe that for the majority of years of the last two centuries this valley was filled with noise and dirty industries. Drift mines in the valley sides, the fire brick factory, the coke and the tar works, and the rail lines that serviced them all. We're almost in Newcastle, but there's one more stop, the Metro Centre, a big shopping mall built in the nineteen eighties on a former industrial site, part the ash tip for the Dunstan Coalfired Power Station, but with an enormous amount of inert material that was put in there to stabilize it too, because it was once a marshy, unstable and pretty unattractive development prospect. And at last, you were probably thinking, we arrive at our final destination, Newcastle Central Station. It sits well above the river level and needed some clever engineering to build the bridges to span the river Tyne, which is no longer a broad floodplain, but has narrowed to a gorge. The broader valley heads not east but south through the Teams, and onwards towards the river Weir. The story here is one of a large glacial lake and changes in river direction, leaving the Team Valley with just a small stream in it, and the Tyne cutting a gorge to Tynemouth and the North Sea. You'll probably remember I wasn't fond of the stone choice for Carlisle Station. It was an alien sandstone. I do like Newcastle station, though. Its architect John Dobson, a man who was responsible for a lot of the classic Newcastle buildings, chose local stone for all those famous streets, and architecturally outstanding buildings in Newcastle. There's Grey Street and the rest of Granger Town. Like this station, they're all constructed of the same local Carboniferous sandstones, from places like Denwick and Hedden and Springwell and Forestones and Kenton. You may or may not agree with my geological glasses. I don't ever take them off, I think. But cities and towns to me look best when they fit with their natural surroundings. And that's the end of this trip across the country. Small island, aren't we? I'm not sure what to do for the next podcast. I've been thinking about heading down the rail line along the Cumbrian coast to Barrow, and then to Carnforth. But the garden and the house are in need of attention, so that might take me a little while.