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by Ruth Deike, Executive Director

    I won't guarantee to satisfy your curiosity, because you may end up with more questions.  What my blog will do is talk about how the Earth works.   Why are there earthquakes; Why volcanoes, and where; What kind of rocks will make good soil for growing potatoes; Will the glaciers come back; Why is the ocean floor younger than the continents; and, What would you like to know about the geology of your home town??  Oh, and, What is geology?

Sea Level DOES Change

Saturday, April 19, 2008

    The more we study it, the more the Earth gets, "curioser and curioser", (to quote Poo and Piglet).  Take for example, sea level change.  Mystery #3 asks us why shark's teeth are found in a muddy rock layer exposed in a cliff way above a modern beach.  We learn that water deep enough for sharks to swim in once covered the land where today the shark's teeth layer is found.   So how can this happen?

    Well, if the amount of water in the ocean were to increase  while the ocean basin stayed the same size - then, like water in a pot, the sea level would rise.  And as we are learning, melting glaciers can cause the amount of water in our ocean basins to increase.

    But there's more.  Let's say there are huge pressures slowly  pushing the land up.  We know this happens because satellites swinging around the Earth measure land elevation very, very accurately and we have learned that the land surface moves vertically up and down!

    OK, so we've got two reasons for sea level to change - can anyone think of others?   How about changing the volume of the ocean basins?  Imagine, not a pot, but water ponded in the middle of a large waterproof sheet.  Now, let's push the sheet up from underneath.  The water level rises because we have made the "ocean basin" smaller!  Yep.  Many scientists think that's what happened about 100 million years ago when much of Europe was under water some 250 to 300 meters (about 750 to 900 feet) deep; and, what is now the United States was two large islands with a shallow sea between them.

      This was kind of an unusual time in  the history of the Earth.  The climate was warm and the sea was teeming with little plants called  coccolithophorids.  Shells from these critters accumulated on the ocean bottom and have made thick layers of white chalk including the White Cliffs of Dover in southern England and a well-known Texas rock called the Austin Chalk.  There's more about what happened 100 million years ago in Mystery #161.

    So now we know there are several ways that sea level can change.  Is your head buzzing and your imagination stretched thin?  Well, check out Mystery #3, and welcome to geology - where there are always scientists to suggest why the Earth works the way it does.

posted by Ruth Deike at 10:27 am - 0 comments

The First Blog - a Big Crunch

Thursday, April 10, 2008
    What? Me do a blog?  I thought blogs were for political wonks and other opinionated folks.  I'm a scientist and I'm supposed to be objective.  And that's probably boring.

    Or is it?  I'm a scientist because I'm curious about how the Earth works -- and  what I've learned is so exciting that I have never in 40 odd years felt bored.

    Here's an example:  Did you know that the huge pieces of real estate called continents are moving!  Yep.  If you live, say, along the eastern part of the North American  continent  you are moving toward San Francisco!  And pretty fast, geologically speaking.  Each year you will be about four centimeters closer to the Golden Gate Bridge!  That means you are moving about as fast as your fingernails grow.

    And there's more.  San Francisco isn't sitting still.  Riding on a big slice of western California, S.F. is moving north toward Alaska!  Now, when two parts of a continent  are moving in different directions there's bound to be a crunch, and that's what's happening along the San Andreas Fault in California.  Big Crunch.

    So, is the Earth an exciting place?  You bet.  And Earth Science is the process of discovering just how incredibly dynamic our planet is.

    Curious?  Send me an email with your questions:

posted by Ruth Deike at 10:33 pm - 1 comments
Herb Duey said... Thursday, April 16, 2009 @ 2:02 pm
Ice ages VS. Evolution Does the presence of Ice caps enhance evolution? Major ice ages are major eras of evolution.. And we ar a result of thr last. Also Cambrian, Devonian, Permian Hmmmm

Ruth Deike
Rock Detective Geoscience Education
395 Deer Run Drive
Nellysford , VA 96080

Phone: 434-263-3737



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