Erosion.  Anyone familiar with my blog might wonder why I would put out a post on something like erosion.  After all, the majority of my blog entries deal with history, not ecological issues.  The fact is, history cannot be separated from ecology.  Ecology has been one of the great driving forces of history, contributing to waves of migrations and the fall of great empires.  Conversely, history has impacted the environment, causing huge changes in flora, fauna, and the landscape that supports them.

Of course, the "environment" or "ecology" entail far more than could be covered in a blog like this.  I'm therefore focusing this post on just one small aspect of ec0logy.  I have chosen to look at erosion.  We see erosion everywhere.  Sometimes its effects are minimal;  quite frequently not.  I'm not trying to make any partisan points.  Erosion is not a Democratic or Republican issue.  It simply is.

Here, then, is a little look at erosion.

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The effects of erosion are often most apparent in arid or semi-arid regions, where vegetation is too sparce to hold the soil in place against strong winds or thunderstorms.  Pictured below is a scene in West Texas, near the city of San Angelo.  This part of the country is subject to extreme droughts, broken by the occasional violent thunderstorm.  The result is the appearance of gullies that slowly eat away at the earth:

Of course, water is not the only natural factor that causes erosion.  Just as consequential is wind.  In fact, wind may be a greater factor than water.  We've all seen photos of massive wind-driven dust storms like this:

This is a famous photo taken in the Texas Panhandle during the height of the Dust Bowl years of the 1930's.  These dust storms were caused by high winds and draught, of course, but were also caused by human activity.  Overgrazing and poor farming techniques were the greater cause of the Dust Bowl than natural weather conditions.  So great was the loss of top soil between 1925 and 1940 that much of the Great Plains today are actually about four or five feet lower in elevation than when European-Americans first settled there.

Wind erosion is not entirely a thing of the past.  Although dust storms like the ones that occurred during the 1930's are rare in America today, they still occur in other parts of the world.  Even in America, dust storms are still a common occurrence.  I once drove from Abilene to Lubbock, Texas, and nearly had to pull over to the side of the road due to poor visibility caused by blowing sand.  That dust storm was not life-threatening like those of the Dust Bowl, but it was very unpleasant, and looked a lot like this photo that was taken a few years ago in Lubbock:

When European-Americans first came to the South Plains, they looked on a landscape covered with tall grass prairies in the east that slowly gave way to short grasses as they travelled west.  When the settlers introduced cattle to that drought-prone country, the native grasses were quickly depleted.  When ranching proved to be unprofitable, farmers plowed the sod and replaced the deep-rooted natural grasses with shallow-rooted wheat and oats.   That was fine as long as the rains came, but when draught hit, there was nothing to hold the dirt in place.  The dirt blew away, exposing the limestone bedrock.  Nature hates a vacuum though, and soon hearty prickly pear, mesquite, huisache, creosote, and juniper replaced the grass on land that had lost much of its fertility.  The result is a landscape that looks like this throughout a wide swath of the Southern Plains:

The effects of erosion are usually not aesthetically pleasing, but that is not always the case.  A million years of erosion have created one of America's hidden scenic gems, the 100 mile long Palo Duro Canyon in the Texas Panhandle, a small portion of which is pictured here:

Nowhere are the effects of erosion as immediately apparent as along the coast.  As polar ice caps in Antarctica and Greenland continue to melt into the sea, we can expect coastal erosion to accelerate with huge economic consequences.  Of course, some argue that global climate change is a naturally occurring phenomenon, and the melting of the ice caps would occur regardless of human activity.  Certainly, there is support for this idea in the historical record.  There was far less ice in Greenland a thousand years ago than there is today, and the milder climate of those days enabled the Vikings to establish fairly successful colonies along the Greenland coast that lasted for hundreds of years.  While it seems likely to me and most of the scientific community that human activity is behind modern climate change, natural factors could certainly be playing a significant role as well.

There is no doubt, however, that a lot of coastal erosion is the direct result of human activity.  When people put buildings on the beach, they disrupt the natural distribution of beach-creating sand.  When we dredge shipping channels through a barrier island, we disturb the natural flow of water in and out of the leeward bays and lagoons.   Couple that with the jetties that prevent channels from silting over, and the effect on the beaches is noteworthy.  Just look at this GoogleEarth image of the Matagorda Peninsula on the Central Texas coast.  Blocked waves and currents have greatly reduced the landmass southeast of the jetties:

Continuing further up the coast to Galveston, you will reach Highway 87.  This highway was built parallel to the upper Texas coast about the time World War II started.  That coastline, stretching from Texas all the way to the Mississippi River delta in Louisiana, has experienced severe erosion during the past several decades.  In fact, the coastline has receded so much that a 20 mile stretch of Highway 87 is no longer passable.  Just take a look at this GoogleEarth image that clearly shows remnants of highway pavement being battered by the surf:

 Here is a close-upview of what was once a busy highway:

Highway 87 manages to become a functional highway as it moves inland closer to the Texas-Louisiana border.  The coastal erosion is less visible in much of Louisiana since a large part of that coastline is far removed from highways and other roads.  The impact of erosion, however, is even greater in Louisiana than it is in adjacent areas of neighboring states.  One of the most drastically affected coastal areas is the Mississippi River delta.  Take a look at this map of the southern reaches of Plaquemines Parish, which includes the delta:

Most maps will show an image similar to this, with a long finger of land extending out into the Gulf of Mexico.  These images are really out of date, and do not take into account the loss of shoreline that has taken place during the past 20 years.  This satellite image of the exact same part of Plaquemines Parish illustrates just how much erosion has taken place in the Mississippi River delta:

Want more?  Here is a photo of the Chandeleur Islands Lighthouse taken in 1960:

Now take a look at the same site in 2001.  The island has receded at least a hundred yards,, and it is much smaller than it was in the earlier photo.  What's more, as the Gulf waters encroached on the lighthouse, the old lightkeeper's quarters were eventually washed away, and all traces of that home have been obliterated:

 The Chandeleur Lighthouse took a direct hit from Hurrican Katrina in 2005.  You may be wondering how it fared during that terrible storm.  The answer is, it didn't.  All traces of the lighthouse were washed away by Katrina.  In fact, all traces of the northern Chandeleur Islands were washed away.  The islands are slowly regenerating, but the human history has been forever removed.  It's a pattern that will repeat itself on coastlines around the world as we enter an era of higher seas and more violent weather.