Today, I’ve got a batch of additional photos of the Walker Top Granite to share, variably mylonitized (sheared out under ductile conditions)… Nice garnets in some spots: Delta porphyroclast: Lovely sheared-out rocks…
The Friday fold is seen at one of the stops on Callan’s pre-GSA-Charlotte field trip: a small waterfall in North Carolina’s Inner Piedmont.
Another Friday, another fold. …By another Bentley!
The Friday fold is a selection of five fold photos from the Selkirk Fan in the Omineca Belt of British Columbia, submitted by structural geologist Marek Chichanski of De Anza College (California).
The Castner Marble is an extraordinary Mesoproterozoic limestone (later re-crystallized and metamorphosed) that exhibits some primary structures (both explicit and ambiguous) and some secondary (tectonic) overprints. It’s exposed in the Franklin Mountains of west Texas.
First thing we saw on the post-InTeGrate field trip to the rocks of El Paso, Texas, was this contact between the aforementioned Campus Andesite, and the Cretaceous sedimentary rocks into which it intruded (contact metamorphosed in the area of this photo): I decided to try switching up my annotation fonts. Whaddya think?
Today, two examples of outcrops that reveal an overprinting relationship between metamorphic cleavage and sedimentary bedding. Both are Devonian in depositional age, from the new stretch of New Route 55 in West Virginia, west of Moorefield. The first is from limestones of the Helderberg Group, and the second is from shale of the Brallier Formation. … Read more
With my new “macrogigapan” rig from Four Chambers Studio, I produced a single image last week as part of my Mid-Atlantic Geo-Image Collection project (M.A.G.I.C.). I’m still learning the ropes of the machine – I shot about 3 times as many photos as I needed to to make this gigapan. Lessons learned, yet again. Anyhow … Read more
…in an Archean schist within the Superior Craton. Same outcrop as the criss-crossing dikes I showed yesterday. We’ve got tourmalines on the plane of foliation in the Setters Schist in Maryland, too, but they aren’t aligned like these Canadian tourmalines; instead the Maryland ones are scattered willy-nilly across the plane of foliation, like pencils on … Read more
Other members of the geoblogosphere have been posting brief image-heavy missives on labradorite over the past 24 hours. Collectively, they remind me that I’ve got a backlog of photos from the Adirondacks of upstate New York to share. Here are a few scans of cut and polished cobbles of the anorthosite from the Adirondack Massif, … Read more