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Wednesday, March 7, 2012

The Essentials: Observations in Brief


We have a very brief time here on Earth, so limited in fact that there are certain events that we have no possibility of perceiving.  The planet itself is a giant dynamic system that moves and shapes itself into continents, mountain ranges and expanses of ocean.  Unfortunately we don’t notice any of this stuff happening in front of us because we are not around long enough to see it unfold (in any significant way).  From birth to death the overall composition of the Earth is pretty much the same.  North America is an ocean away from Europe to the east and an ocean away from Asia to the west and has been for a really, really long time. 
While we can’t see the movements of the Earth in our lifetimes there are ways we can know that the continents have been otherwise arranged in the past.  Many people look at the world map and recognize that the continents look like they could fit together like a jigsaw puzzle.  In fact the continental boundaries that look like they fit together show evidence that at one point they really did.  As one example, similar rock layers and even fossils are found on the edges of separated continents where the land used to meet.  Modern laser guided, space based measurements show that continental movement is measured in centimeters per century so it is no wonder that we can’t see it happening in front of us.
Evolution faces a similar challenge because it occurs over extremely long periods of time.  When we look around we see a collection of animals, plants and other organisms that seem to always be the same.  Really in terms of the short time we are on Earth the collection of animals, plants and other organisms are pretty much the same. It takes a really long time for change to accumulate in a population just like it takes a really long time for an entire continent to drift thousands of miles away from land it used to be connected to. But just because there are challenges to observing super long term events doesn’t mean they haven’t happened or that they can’t be detected.

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