From slush to ice.

On the same walk where I got the marvellous shots of the frozen, slushy waves, I found something else that I wanted to share with you.  Here in this pond behind the beach: do you see them ?

This brackish pond just above the tide line was frozen solid.   No, no, I know you've seen frozen water before.  It's not the ice I want to show you:  it's what's in the ice.

Without realizing it, Trey is pointing them out to you.   Can you see them ?

There in the ice was something that amazed me enough to go back home to get fresh batteries for my "dead" camera, and come back out in the bitter cold.   There in the ice was something I'd never seen before.

Gingerly I folded myself down and lay on the glassy surface, and pointed my inadequate camera downwards.

And this is what I saw ...

BUBBLES !

Stacks and stack of  bubbles.

Stacks of flat bubbles.

Isn't that the coolest thing ?

What on earth caused these frozen, flat bubbles ?   I checked with Mr. Google and he sent me to New Scientist's Question and Answer science page, where I found this explanation:

"In ponds and lakes, the biological activity of microbes in the sediments on the lake floor produces bubbles of gas, usually methane or carbon dioxide.  In winter this activity is slow, but it is still present.

The gas bubbles rise to the frozen surface, becoming trapped there.  The following night another layer of ice forms beneath the bubble, so it is encased in ice.  This leads to the flattened shape you see.  The picture is a frozen daily record of the gas emissions."

Now to add to the fun:

"...If you'd like to find out if it is methane that is trapped inside the bubbles; make a tiny hole in the ice directly to the trapped gas inside the bubble and light it.  If it's methane, you'll see a flame ..."

Got a match ?