This Week's Experiments

We did a couple of simple demonstrations earlier this week to show the eroding power of water and how it can change landscapes.  First we took a small bar of soap:


and then allowed it to sit under a slowly dripping faucet for a couple of hours:



After some time had passed, it looked like this:



The other demonstration involved stopping up the end of a drinking straw with clay, filling it up with water,

 then stopping up the other end with clay.   

Then we put it in the freezer for a couple of hours:



When water freezes, it expands.  So:





The expanding water/ice forced a "plug" of the clay out of the end of the straw.  When water seeps into cracks in rocks and then freezes, it basically does the same thing - it forces the crack open a little farther.  As the ice melts, it carries away small bit of the broken rock.  The opening is a little bigger, meaning more water can seep in, freeze and thus make the crack even larger.

Now... I have to point out that in that last picture, Landon is not actually studying the plug.  Really he is frowning at me from under his eyebrows because I am making him hold the straw for the picture.  He wanted to TAKE the picture.  So the one above that is the one I let him take.  LOL

I also noticed that my photos of these scientific endeavors have also showcased some housekeeping areas that I would honestly rather that the world did not see.  Bathroom sinks (disclaimer: sinks that the kids are responsible for cleaning); kitchen counter (mercifully far enough in the darkened background that perhaps only I am bothered by it); and the freezer.  I am laughing at the Phlly Steak box.  But it did make a nice level spot to rest our straw on!