This week’s edition of the “Friday fold” takes us to Route 55 in West Virginia, to deformed Appalachian strata of the Valley and Ridge province. A few bonus structures are also shown — some ripple marks, slickensides, and pencil cleavage.
The penultimate episode of Callan’s more-than-a-week-long series on the geology of the San Francisco region: today we briefly visit the sand dunes that covered San Francisco Peninsula during the Pleistocene.
The geological tour of San Francisco continues with an examination of the graywacke deposits of the
Part 4 of the ongoing series examining the geology of the San Francisco area. In today’s post, Callan visits Kirby Cove in the Marin Headlands, where intensely deformed chert can be found on one end of the cove, pillow basalts on the other, and an “artificial dune” in the middle.
Episode three in the multi-part series on the geology of San Francisco. This post focuses on the chert layers of the Marin Headlands
Second in the on-going series about the geology of San Francisco: this post explores the pillow basalts of the Marin Headlands Terrane.
A detailed description of one of the Virginia Blue Ridge’s most intriguing geologic formations: a maroon sedimentary sequence showing the advance of “Snowball Earth” glaciers in the Neoproterozoic.
Yesterday, I asked for you to evaluate this rock sample of the Belt supergroup and tell me how many structures (both primary and tectonic) that you could identify in it. Thanks to everyone who participated in the discussion. Here’s my annotated copy of that photo for comparison:
Last summer, in Bonner, Montana on my Rockies field course, I took the students to see some nice exposures of Belt Supergroup strata on the side of the road. We were keeping our eyes peeled for both primary structures (i.e., patterns in the sediment that formed at the time of their deposition) and secondary, or … Read more
Jason Buchheim, one of the people I met last week in Pittsburgh, just posted a Gigapan of images stitched together from the Mars Observer MER HiRise. Part of it jumped out at me as being similar to the map pattern we see on Earth where an angular unconformity outcrops: Here, I’ve highlighted the pattern which … Read more