Lago Grey: A Scientific Explanation

At the end of April, while our Aussie guests were here, we all flew together down to the far south of Chile.  We were heading into the pampas – the thousands on thousands of rolling kilometers of open southern grasslands, going to Puerto Natales and the Torres del Paine.
We were going tower hunting.

 

Icebergs are blue. Electric Blue. Celestial blue. 
            So are the rivers that flow away from glaciers, and the lakes that these rivers flow into, something that has always confused me. I had been taught that the celestial properties of icebergs are due to the way light rays percolate through the ice, and I didn’t see how that could translate to the ice when it melted.
            I have since learned that the vivid color comes from rock flour, ground out of the Torres del Paine by the moving glaciers and suspended in the water.  Nine years ago, however, I heard a different explanation.
            In the summer you can go up to the face of the glacier in little boats –chugging along the ice face, hugging the curves and crags and chipping ice cubes from the glacier and drinking dreadful, three-day old whiskey with celestial ten-thousand year old ice.

Halfway along the lake, we had stopped to pick up a group of campers from a campsite on the lake shore.  That campsite set a new benchmark for blasted, benighted and windswept, but the campers – a group of students from Santiago, were full of enthusiasm.
It was a mixed group, and the girls were inclined to worshipful adoration of the males.  Up against the ice face, one of the girls spoke -
            “The ice in that cleft is so blue it’s almost turquoise. Why is the ice so blue, Hari?”
A student in the middle of the pack smiled and stood tall.
            “Ah."  He said. He cleared his throat. "Ah ha.  You know how water is made up of two H molecules and one O molecule?”
           “Yes!”
            “Well, it’s the H molecules that make ice white.  When ice goes blue like this it means that all the H molecules have melted into the lake.  That ice is there mostly O.”
            “Ohhhh."  The girl looked up at him with doe-like adulation. 
From the back of our little crowd, a voice rose in a distinct Australian drawl.
            “I’m guessing that none of you lot study Chemistry, then?”
            I’m not saying that it was one of us. It might have been, but on the other hand, it might not. There were a lot of people on that boat. It could have been anyone.
            Hari went back to more traditional means of impressing girls – flexing the muscles in his arms (the muscles in his brains having proved pretty much impervious to flexing) and drinking too much whiskey on ten-thousand year old rocks.

Those were some rocks.  That water was the most pure water I’ve ever tasted.  It tasted of theology; you could conceive of a pristine world, where the rain fell on antediluvian man through a sky that had never heard of aerial pollutants.  Sucking on a chip of ice was like drinking explosions of absolute nothing.  Like peppermint without the mint.  Just the explosion.