GoSF9: Pleistocene dunes
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.
sediment
GoSF6: Graywacke turbidites
The geological tour of San Francisco continues with an examination of the graywacke deposits of the
GoSF4: Kirby Cove
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.
GoSF3: Chert
Episode three in the multi-part series on the geology of San Francisco. This post focuses on the chert layers of the Marin Headlands
Animated laminae
More of the new scientific medium* I showed you on Wednesday: animated GIFs of super-small stuff, to give a sense of depth. This time, I included a 1 mm scale bar: These are laminations of silt and clay in the rhythmites of the lower Konnarock Formation. If the above image moves too fast for your … Read more
Gravel and sand
Another image from Turkey… Tell me, fluvial folks and sedimentary soothsayers, what do you see here? Here’s a bigger version, if that helps.
Reduction rims?
Another look at Konnarock Formation diamictite, showing colorful reaction “halos” around some clasts.
The Konnarock Formation
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.
How many structures can you see here?
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
Tavşanlı Zone field trip, part 5
After our mind-boggling encounter with the limestone strata turned lurid pink by their high-pressure encounter with subduction, our band of merry geologists set off for a stroll: We began the walk in greenschist + blueschist mélange, as seen here with a Turkish 1-lira coin (26 mm diameter; about the same size as a U.S. quarter) … Read more