It’s back to Alaska this week, for another look at traces of a glacier’s passage. This shot’s from the Tracy Arm fjord:
You can see faults in the rock running roughly vertically. But those horizontal grooves? They’re the tracks of the glacier that once filled this valley — as the glacier headed out to see, bits of rock that it had already broken off became grit to further erode the bedrock left behind.
Oh, and if you ever get the chance to take a cruise of Alaska’s fjords, take it!