[Tweeters] Glaciers Don't Retreat
gibsondesign15 at gmail.com
Thu Aug 2 21:57:23 PDT 2018
Oh sure you've heard all about the semi-tragic retreat of glaciers
worldwide. Oh well, it's happened before. Here today, gone in some hundreds
or thousands of years later.
However, glaciers don't really retreat. It's not like they crawl back up
the mountain, or go back to Canada for another load of rocks. No, glaciers
just melt, dropping their load of rocks and stuff right where the glacier
melts out from under them.
I got to see this in action while working at Mt.Rainier for a few summers.
I lived in employee housing overlooking the Nisqually glacier, occasionally
hearing a big roar of rockfall off the far side where the glacier was
undercutting the ridge, the rock and dirt fanning out over the surface of
the glacier, where, covered by the next winters snowfall it was
incorporated into the ice. If the glacier advanced, the rocks got carried
downhill maybe, but the rocks were just applied where they melted out -
possibly in a moraine, which is a ridge formed by rocks melting out of the
glaciers edge and bulldozed off to the side by the still moving section of
ice or left at the glacier's terminus.
The fascinating and beautiful beach cobbles of Port Townsend are largely
from elsewhere,the granites and gneiss, quartzites and serpentine are not
native to the Olympic Peninsula. I like serpentine because of its beautiful
patterns and the fact that it's hard enough to take a high polish, yet soft
enough to work with diamond files and polish with wet sandpaper. (got to
examine carefully though because some of it contains asbestos), Sometimes
sitting at this computer watching something that only takes a half-wit of
attention (national news for example) I wet sand little serpentine pebbles
or cobbles that I'll give away to friends as good luck stones. Found a
real purdy one this morning, probably eroded out of the massive cliffs of
glacial till around here.
It is shorebird time again and watching the muddy edges at Kah Tai lagoon
yesterday saw 3 Greater Yellowlegs, 3 Short-billed Dowitchers, several
Killdeers, a whole lot of Barn Swallows and a single Virginia Rail lurking
in the tules.
Port Townsend Wa
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