Tuesday, September 9, 2014

Geo 730: September 9, Day 617: In the Same Vein...

No, wait, actually, this is a different quartz vein, down at road level (no climbing!), and maybe 75 yards farther along the (blocked) logging road. The crystals here are nothing to look at, but the context is perhaps somewhat clearer than at the big vein up on the hillside, which has been stripped of the surrounding host rock. This one tapers off as it rises from beside Dana's left foot, up along her side, then appears to thicken again a few feet over her head. Notice that the rock on either side of the vein is much less competent, and weathering more quickly, than the vein itself. There's a second vein on the left side, heavily stained with bluish-black manganese oxides, which looks as if it's older. However, it may have simply been exposed to weathering for a longer period of time. There was some excavation and roadwork (new exposures opened up) prior to this area being logged in the late 1980's. So the "younger" vein may simply reflect more recent exposure.

Photo unaltered. July 9, 2012. FlashEarth Location.

No comments: