With the recent devastating volcano in Hawaii, I thought it would be appropriate to discuss some natural geologic forces.
Earthquakes and volcanoes are, in geologic terms, called constructive forces. They can cause great destruction but here’s the point: they bring new material (lava, magma, volcanic ash, etc.) to the surface. These fertile rich materials supply the depleted soil for growing things in addition to changing the appearance of the earth’s surface. These are building up processes similar to anabolism in living cells that I will discuss in another essay.
On the other hand, weathering and erosion are destructive forces because they tear down surface features and wear them away. The major agents of weathering include wind, rain, and temperature changes (freezing & thawing). Potholes in the pavement in the spring are a good example of the effects of freezing & thawing. The major agents of erosion are running water, wave action, wind, gravity, and loss of ground cover. Weathering and erosion can be compared to catabolism (tearing down processes) in living cells. It is interesting that constructive and destructive forces in geology are complementary processes like photosynthesis and cellular respiration are in biology.
Once again we find that we humans constantly leave our “footprint” on these processes and, therefore, on the face of the earth. Drilling, mining, construction, logging, and farming are just a few ways in which we have altered the face of the earth’s surface and subsurface. Moreover, the effects of underground bomb testing by the United States and Russia years ago are not fully understood.
Let’s back up a little. Most of you have probably heard of plate tectonics and continental drift. The continents are moving and this movement can even be measured. Alfred Wegener, a German meteorologist first proposed the idea of continental drift in the 1920’s. The Rocky Mountains were formed where the Pacific and Continental plates collided; the Alps were formed where the African and European plates collided. Interestingly, some of the tallest mountain ranges are found under the Pacific and Atlantic Oceans. Iceland sits on the Mid Atlantic Ridge and is volcanic in origin. These ridges are where faults and volcanoes often occur. If there are ridges where continents collide, there must be trenches where separation occurs. Indeed, the Marianas Trench, which at over 7 miles deep, is deeper than the tallest mountain. These trenches represent subduction zones where one layer sinks below another pushing solid rock down where it is heated by radioactive elements to a molten liquid state and recycled again. This all lends support to the Planetesimal Hypothesis which holds that the earth and other planets were formed by cohesion of particles about 4.567 billion years ago. The asteroid belt between Mars and Jupiter probably represent particles that never quite formed a planet or one that broke apart.
To learn more about this and other topics I have discussed or will discuss in the future, check the Science Channel, National Geographic Channel, or the History Channels. In particular I would recommend the following series: Naked Earth, The Universe, or Miracle Planet