The Tar Tunnel of Coalport EarthCache
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The Tar Tunnel of Coalport
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Car Park N52 37.190 W02 27.110
The Tar tunnel is another remarkable and interesting feature of the Ironbridge Gorge.
Located along the banks of the River Severn in the Village of Coalport, the tunnel starts near the foot of the Hay Inclined Plane and runs under the hill for at least 1000 yards.
The Tar tunnel was dug from the hillside in 1787 - probably in connection with the nearby coal workings. The miners struck a gushing underground spring of thick, treacle-like natural bitumen (also known as Asphalt).
Note!
Commonly called the "tar," the liquids that seep out of the ground are actually comprised of bitumen, not tar. Tar is a commercial by-product made by the distillation of woody materials, such as coal or peat, while bitumen is a naturally formed substance comprised of hydrocarbon molecules.
Geological origin
Naturally occurring deposits of bitumen are formed from the remains of ancient, microscopic algae and other once-living things. When these organisms died, their remains were deposited in the mud on the bottom of the ocean or lake where they lived. Under the heat and pressure of burial deep in the earth, the remains were transformed into materials such as bitumen, kerogen, or petroleum.
Check the photos attached
A bit of History about The Tar Tunnel of Coalport
In 1786, a local ironmaster, William Reynolds, started to build a tunnel from a meadow on the banks of the River Severn towards the mine shafts at Blists Hill. The largely brick-lined tunnel was intended to be used for a canal to transport coal from the mines. However after about 300 yards the workmen struck a spring of black sticky stuff (tar), or more correctly, natural bitumen. Reynolds immediately realised the scientific and commercial potential of this discovery and started to exploit the resource he had found. Around 4,500 gallons of bitumen a week were collected at first, and for several years over 1,000 gallons were being extracted, however this reduced to only 10 barrels a year by the 1820’s when finally in the 1840’s it dried up altogether.
You don't have to go into the Tar tunnel, to claim the cache e-mail us the answers to the following questions;
Q1) Explain how the tar pools were formed here?
Q2) Originally the tar tunnel was to be a canal tunnel from a meadow on the banks of the River Severn towards the mine shafts and coal seams at Blists Hill.
What geologic Era and Period in time was the coal a sedimentary rock formed?
Q3) To prove you were at the location, how far away is the River Severn from the Tar Tunnel entrance?
Q4) Optional photo at the sign post for the Tar Tunnel
FTF spekey
Additional Hints
(No hints available.)