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.
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| 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
