Transect Trip 10: en echelon tension gashes
Gorgeous back-rotated quartz-filled tension gashes in the Antietam Fm. Sinistral sense of shear:
Gorgeous back-rotated quartz-filled tension gashes in the Antietam Fm. Sinistral sense of shear:
Side view of Skolithos tubes:
Looking down on Skolithos ichnofossils in the Antietam Fm. quartz sandstone:
A few rip-up clasts in arkosic matrix (Swift Run Fm.):
Live geoblogging continues… Here’s some nice round quartz pebbles in the Swift Run Fm:
Neoproterozoic arkose and mudstone above the basement complex:
Multiple anastomosing high strain zones cut through the Blue Ridge basement complex during Paleozoic mountain-building. Ar/Ar cooling ages on muscovite here are 320-340 Ma.
Charnockites are orthopyroxene-bearing granitoids, common in the core of the Blue Ridge Anticlinorium:
With a distinctive orange weathering rind:
Live geoblogging my post-NE/SE GSA field trip: Bill Burton and Chuck Bailey prep the group with a discussion of map patterns in the Blue Ridge…