Tuesday, January 29, 2013

Ecological Issues

I believe I promised a post on the ecological issues around Mont St. Michel. I imagine that most everyone has been told at some point that people have a major effect on the environment and our actions cause changes in the world around us. Maybe you haven't heard that, but I'm sure if you think back to your school days you'll probably remember a lesson about the importance of recycling. We hear all the time these days about how people are affecting the environment in terms of energy consumption. "Fossil fuels", "greenhouse gases", and "global climate change" are just a few of the key buzzwords and phrases that dominate any news story with an environmental theme. We hear a lot about deforestation too: disappearing rain forests, growing deserts, endangered species pushed to the brink of extinction. We hear these stories, and we read the articles in the newspapers and magazines, but for most of us, these are things that are happening far away and that are happening very gradually over time. We also tend to associate these things with some kind of "villainy" if you will; something bad that someone else is doing that needs to be stopped, like poaching for example. What's happening at Mont St. Michel is a very different sort of change in that there's no villain. There's no pointing fingers here; we are forced to admit that a variety of decisions and actions, all of them made with good intentions, have led to this.

So what is happening at Mont St. Michel? Well, for starters, Mont St. Michel is an island just off the northern coast of France. You can read my previous blog about it here. One should be careful here to note that it is not an island all of the time. At low tide, it is possible to cross the sand plains over to the island, but it is very dangerous due to the quicksand. Also, the tides come in very very quickly, so if you were stranded on the plains you could easily find yourself 20 feet underwater before you had time to do anything about it. During high tide, the island is accessible by a raised causeway. Back in the Middle Ages, you actually approached from the opposite side that you do now.

Screen shot of Google Maps 1/29/13, with edits.

I can hear you now, "But Jackie, the other side is so far away! Why wouldn't they come from the same side we do now? Why bother walking miles across a bunch of quicksand and risk drowning in the tides when you could just go around and cross just a little bit of the quicksand?"

Because at one time, that was the closer coast. In the middle ages, what you see as the longer way of crossing the sand banks was actually the shorter of the two routes. As long and perilous as it was to approach from the north, it was much much shorter than coming from the south. People would actually trek around the bay to the north and come down that way. Are you beginning to see what the problem is? The land has been creeping closer and closer and closer to Mont St. Michel. The bay is getting smaller. Pretty soon it won't be an island at all, not unless we do something drastic.

So what happened? Is it a slow death of natural causes? Well, only in the respect that people are natural. The island was formed by the unusually strong tides washing away the softer rocks and minerals from the area, eroding the land until the large granite blocks were left as an island. This would have been following the end of the last Ice Age. After that, things would have been pretty stable for several millennia. Most bays and gulfs experience a certain amount of shrinking. Tides deposit sand and finely ground minerals and these slowly fill in the cracks and crevasses of the coast. However, by and large, the bay of Mont St. Michel resisted this, due in part to the strength and speed of its tides, but also to the number of small rivers that empty out into the bay. Enter polderization.

A polder is basically a piece of land that has been built up by closing it off from water, mainly by using dikes. Basically the idea is that if you live near the coast or on a lake and you want more land for farming or grazing livestock, you go out during low tide, build up earthen barriers around the edges of where you want your new land, and the water will wash in dirt and sand until you've got a nice new marshy field. If you wait a while longer, it will actually build up enough to completely blend in with the coastline. At Mont St. Michel this was done so that the government could have more land to sell as an additional means of funding, as well as to provide additional farmland for the growing French population. Thus they drained lands. Here's the scary part: they did this for about 200 years. From the middle of the 18th century to the middle of the 20th, this was a common practice. On top of it, in order to keep the salt water tides from flooding inland and killing the crops, the rivers were dammed which increased the silt deposits in the bay. Good agricultural practice, not so great ecologically. Remember that picture of the map and how far the northern coast is? The southern coast was once even farther, and that has all changed largely due to polderization.

Polders are not the only problem though. At some point (probably about the time the polders were getting underway) a tidal causeway was built to access the island. At low tide, you could cross by the causeway; at high tide, you were stuck with waiting or grabbing a rowboat. {Even at high tide, the bay is far too shallow for a regular boat to sail in. Historically this made it advantageous as a fortress location, but it also made it more difficult to build.} Then in 1880 they built up the causeway so that it would no longer be submerged even at high tide. This was great for tourism; people could come and go from the island whenever they wanted, and they could ride their carriages, and later their cars, right up to the island. No more of that silly walking business. However, this meant that the tide could no longer encircle the island. More silt built up. Areas were silt had already been heavily deposited started to grow plants and become marsh-like. The marshy areas started getting dryer and more farm-like. The land has crept up right under our noses and if we're not careful, Mont St. Michel isn't going to be an island, it'll just be a hill.

Just over the roof lines you can see the silt
that is now turning into marshes

Don't believe me? If you think I'm exaggerating google Mont-Dol, France. The Bishop of Dol in the 1200s got tired of his local villagers dying in floods or starving to death because their crops were killed by the saltwater tides. He came up with a great idea: put in a bunch of dams and turn the rivers into canals. No more saltwater, no more horrific tides, just nice simple living. Except that they found themselves enclosed by land in the blink of an eye. There's nothing wrong with that. Not everyone wants to live on an island. However, the beauty and majesty of Mont St Michel lies in its unique location, a location that is on the brink of disappearing.

I mentioned before that this was going to happen unless we did something drastic, and actually, something drastic is being done about it. In the 1980s work started to save Mont St. Michel. Scientific studies done in the 1970s  investigated potential solutions that would still respect the rights of the landholders and these set the stage for their plans. After all, much as anyone wants to save a national treasure like Mont St. Michel, there's no need to drown the farmers in the process. Step one: get rid of the old dams at the base of the rivers so that they can deepen the eastern side of the bay. In 2006, the French prime minister announced a project to help get rid of the silt deposits. Step two: build a hydraulic dam that essentially works in reverse of the dams that blocked all the water out. This uses the river water to flush out the bay as the tide goes out. Step three: get rid of the causeway. This is the part they are working on now. They are in the process of building a new bridge to the island which will allow the tides to flow around the island, and hopefully erode away the silt deposits. Then they will tear down the old causeway. Meanwhile they are also working on digging up the old parking lot in the hopes of helping the process along. A new parking area has already been built on the mainland with shuttles that take you across the causeway.

The causeway, and the beginnings of the new bridge
A better view of the work on the new bridge

They're doing a lot to save the Mont. It remains to be seen if it will work. There are some who say that it's already too late. In fact, one study suggested that we passed the point of no return back in 1991. The point is there's a lesson to be learned here: everything has consequences. The actions people take to "control" nature or to try to force the natural world to conform to their wishes have repercussions we can't possibly predict. Something to keep in mind.

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