Walk completed August 16, 2014

Sunday, May 4, 2014


Rivers are the world’s highways, but rivers don’t always flow where transport is needed.  In 1759, the Duke of Bridgewater constructed a canal to ship coal from his mines in southern England to the river Mersey, dispensing with the need for ox-drawn carts traversing muddy, pot-hole filled toll roads, and initiating a new transportation system.  Parliament then passed a series of Canal Acts, and artificial waterways soon linked most of England's major rivers, making it possible to transport goods quickly and efficiently by boat throughout the country.  Canal fever went viral, and before long canals crossed landscapes in the Americas, Europe, Africa and Asia.  Even Mars had its canals.  Canals were built in California solely to transport water, rather than boats.  And in Utah, Mormon pioneers built miles of canals in the desert before somebody realized that there was no water to fill them.  But nobody out did England, which counted more than 2,000 miles of inland waterways -- quite a lot for a small island.  Interestingly enough, all that construction led to a discovery that proved far more important than the canals themselves.

Flowing water creates considerable resistance against vessels moving upstream.  In order to minimize flow, canals must be level; where possible, engineers followed the land’s contours.  If circumstances required, locks were constructed to separate the canals into sections, each of which could be level.  But locks were expensive to build and maintain, and invariably slowed the movement of vessels through the canal.  Furthermore, locks always require a water source to replenish the water lost with each passage through the lock.  When faced with hills along a canal route, engineers typically cut right through them. 

William Smith's Geological Map
William Smith, the engineer hired by the Earl of Bridgewater, noticed that each canal cut passed through multiple layers of earth.  Some cuts had more layers than others, but regardless of the number of layers, no matter where the cut was located, the layers that did exist were always in the same order.   He began mapping the layers, and ended up producing the world’s first geological map. 

Geologists use geological maps like walkers use hiking maps.  Walkers use hiking maps to find pubs; geologists use geological maps to find the things that go into pubs.  Look around yourself, and try to find something that doesn’t come from the ground.  Literally everything we have comes from the ground.  Some things lie right on the surface, but most of the stuff we need lies below the surface. By studying geological maps, geologists can determine where under the surface a particular substance can be found, thus avoiding the need to dig everywhere.  Of course, I didn’t know all of this when I was a child, which probably explains why I spent so much time digging in beach sand looking for buried treasure.

So, although canals were intended merely for transportation, their construction led to discoveries far more lasting.  Indeed, canals lost most of their economic value by the mid-1800s. While one horse pulling a boat through a canal could do the same work as 80 oxen pulling carts, one train could do the work of 80 horses pulling boats.  With the development of railroads in the mid-nineteenth century, England’s canals were mostly abandoned and fell into disrepair, but geological maps are still in demand today.  The demand would be far greater if William Smith had the foresight to include the location of pubs on his maps.

Back when canals were first built, horsepower was actually measured by horses, and not by cubic centimeters.  Because vessels were pulled through the canals by horses, every canal had an adjacent towpath. When the British Waterways Board instituted programs to rejuvenate the canals in the 1990s it had the foresight to restore the towpaths.

Towpaths are now used as often by walkers as by boaters.  Canal-walking is relaxing for both mind and body.  After all, it’s hard to get lost while walking along a canal – if you do take a wrong turn, you have a 50/50 chance of getting wet.  Without the worry of route-finding, you can ignore map and compass, and focus on more interesting things, like the layers of earth exposed by canal cuts.  You are probably already as caught up in the excitement of searching for exposed earth layers as I am, so when I start walking in southern England this summer, I’ll try to walk along as many canals as possible and report my findings. Who knows?  Maybe we’ll discover some things William Smith missed.  If so, I may update his maps, but I’ll be sure to include the pubs.

© 2014 Ken Klug