Friday fold: One from Walcott

My man Walcott contributed a lot of images to the USGS stockpile during his travels. Today, I’ll feature one from Bishop, California, from 1894: Got it from here. Rock hammer on the left for scale. The caption reads: Plicated layers of thin bedded chert in limestone etched by erosion, Lower Cambrian (?). Hill two miles … Read more

Friday fold: Pete’s purty pet

That’s my Rockies co-instructor Pete Berquist, in the regulation uniform of an orange down vest, holding a subtly-folded slab of sandstone (it’s a very slight “S”), rescued from amid the shaley wastes of the Blackleaf Formation, the Cretaceous aged sedimentary rocks beneath the Lewis Thrust on the Blackfoot Reservation, just east of Glacier National Park. … Read more

Cascade Canyon

Following up on Friday’s fold, I wanted to share a few other images from our hike last week in Cascade Canyon of Grand Teton National Park.  Lots of cool exposures of Archean basement rock there. Folds in gneissic banding: Big, angular mafic blocks in a felsic soup: Swarm of granite dikes on a mountainside: Asymmetric … Read more