Wednesday, May 14, 2014
The other day, a friend asked, in all earnestness, why it is that some parts of the nation have one kind of weather or earthly phenomena and other parts have different ones.
Why, for instance, does one section of the country get earthquakes and another have to contend with tornados? Each can be shattering.
It’s a good question. I wish I knew the answer.
But one question has a tentative answer, at least tentatively.
After a long struggle over the matter, it was found that mountains usually are associated with a shoreline. Then how does one account for the Ozarks, which are a long way into the continent?
This brings us back to the process by which mountains are created, heaved up from Earth’s depths, carried toward the continents on the backs of the great plates of the earth’s crust and then the plate carrying them ducks under (subducts) the continent, melts in the intense heat, and often, erupts, forming whole ranges of new mountains.
But the Ozarks are nowhere near a shore. They are well into the continent.
That brings us back to the theory of moving plates of the world’s crust.
We have talked about how Washington was formed piecemeal, as one bit of floating crust after another sutured itself to the growing North American continent, gradually building the continent we know today.
In time the continent can be far inland, gradually closed in by later-arriving sections of the moving crust we now recognize. It took a while, but geology has lots of time.
And its processes are consistent.
We have not studied this phenomenon of the earth’s crust much, if any, beyond our own corner of the country.
But the processes continue, whether we follow them or not.
One of the things that awes me is the contention of scientists that the present parade of continents is not the first. It has happened before, they say.
The tendency of the Earth forces to erase earlier events with later ones makes it very difficult to read.
Aside from references to the fact that there has been such reshaping, I have never seen a work on such an earlier migration of continents or parts of continents.
Even so, isn’t it intriguing just to know that no matter how little we know about it, it did take place?
And some day, some brilliant scientist may be able to unlock the puzzle for the people who live here then.
If they are at all like us, there probably will be an argument about it.
Elizabeth Widel is a columnist for The Chronicle. This is the 2,887th column in a series. She may be reached at 509-826-1110.