Saturday, January 21, 2012

Erosion vs. Weathering

I never really explained why I named this blog what I did, but there is a reason. You see, since I'm an undergraduate student (for only two more semesters) I wanted to tell the story of my journey from lowly and ignorant undergraduate through graduate school and into my own career (however long that takes). However, that only makes sense if you know the actual definition of erosion:

Erosion-The physical removal of rock by an agent such as running water, glacial ice, or wind.

And compare that to weathering:

Weathering- The group of processes that change rock at or near the Earth's surface

Now why do I care about that?  Well besides confusing the two makes it seem like I feel like my education is disappearing or being torn down some how, the real problem is that erosion is used as a literary device by several people and it is almost always used wrong. Here are two examples:

Now I understand that educational erosion makes a good almost alliteration (look at my blog title) however, they are not describing erosion.  They are describing weathering, and there is a fundamental difference.

Weathering can be broken up into two categories, chemical and physical. Physical is the easiest to understand, as it is simply mechanical processes which break apart the source rock. Examples include frost wedging, water running over rocks or rivers down cutting into the ground, wind sand blasting formations, or even animals walking over the same trail numerous times.

Chemical weathering is different.  This is when the minerals withing a source rock are changed into different minerals, which is often caused by water. Near Albuquerque are the three peaks, three inactive volcanoes which spewed basaltic lava thousands of years ago. On these volcanoes you can see the mechanical weathering from the water flowing down the slopes creating the classic V-shape indicative of mountain streams. However, the most interesting part is that where the black lava is along the stream, you can see how high the water gets when it does flow. As the once black rocks are turned white where they were submerged in the stream. This is due to chemical weathering, the Calcium Feldspars, indicative to basalts, are chemically weathered into calcite, a much softer mineral, which compromises the integrity of the formation.

Erosion, on the other hand, is all about transportation.  So while the forces of weathering and erosion may be the same, the processes are different. Weathering breaks down a mountain, while erosion spreads the pile of rubble far and wide, flattening out the landscape. Some of the mechanisms of erosion include landslides, turbidity flows, rivers, and wind.

So please remember, I'm on an educational journey and my education is not being torn down. Thank you

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