GoSF6: Graywacke turbidites
The geological tour of San Francisco continues with an examination of the graywacke deposits of the
structure
Friday fold: Mars Hill terrane
Today’s Friday Fold comes to us via Pete Berquist of Thomas Nelson Community College in Hampton, Virginia. Check it out: Pete explains what’s going on here: I cannot provide an exact location but this is within the Mars Hill Terrane (MHT), which is an distinctive swath of Mesoproterzoic basement extending ~50 km x 100 km … Read more
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
Friday fold: monastery brick
Sometimes you find folds in funny places, like the side of a monastery. Guest fold from Maitri.
Faultcano
Visit the “faultcano” in the Owens Valley of eastern California: a cinder cone which has been cut and offset along a normal fault associated with Basin & Range extension.
Three joints
Long-time readers (and students) know that I have a special corner of my heart reserved for plumose structure and hackle fringes, that finely-filigreed anatomy of a fracture surface. Fractures are everywhere in rocks, and often they show neat little “topographic” details that show fracture propagation direction and stress fields. Here are three that I haven’t … Read more
Friday fold: sketchy syncline
For the structural geology fans among AGU’s readership, enjoy the weekly installment of the Friday fold.
Focusing on S-C fabrics
An animated image showing changing focus on a microscope camera aimed at a sample of S-C fabric is shared. Readers are encouraged to brainstorm uses for animated GIF images in the geosciences.
Friday fold: gneiss one!
One other thing that I noticed during my visit last weekend to the Virginia Museum of Natural History in Martinsville, Virginia, was this fold. As soon as I saw it, I squealed “Oooh! That’s going to be the Friday fold!” It says something about the crowd I was traveling with that everyone (a) knew what … Read more
Tavşanlı Zone field trip, part 7
Part 6 of the Tavşanlı Zone field trip had us looking at some blueschists and eclogites. Today we conclude the terrific field trip with a brief look at a couple more stops.
Friday fold: the Scottish coast
Whilst searching the coastline of the U.K. for Where On Google Earth? #226, I found these lovely folds exposed in wave-cut platforms on the east coast of Scotland. I missed the actual location of the Google Earth screenshot (It was in Wales, and Anne Jefferson found it), but I’m happy enough to have found some sweet folds exposed in map view.
How many structures I saw here
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:
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
Friday fold: Belcher Islands, Canada
The Friday fold this week is the sinuous shape of the Belcher Islands, Canada.
Extended tomb
This summer, strolling atop the massive travertine terraces of Pamukkale, Turkey, I checked out the necropolis (graveyard) of Hierapolis, an ancient city founded around 200 BCE and abandoned after an earthquake in 1534. One thing that caught my eye there was this tomb, built of travertine blocks.
Joint sets at Pamukkale, Turkey
A lot on my plate today, so I’m just going to toss a random photo from my summer trip to Turkey up on the blog for today. This is a block of building stone at Hierapolis, the Greek spa resort atop the travertine mounds of Pamukkale, in central Turkey (near the town of Denizli). Check … Read more
Microfaults-a-million
I got to Pittsburgh around 1:30pm yesterday, which meant I had several free hours before the opening reception for new Fine Fellows. I took a bunch of photos of the exhibits there, but my traveling laptop doesn’t have the image processing software that I usually employ to resize these things, so for now I’ll just … Read more
Friday fold: a gummy worm
A week ago today, I went out on the Billy Goat Trail (near Potomac, Maryland) with a group of students: five from George Mason University’s GeoClub, and two that are current Physical Geology Honors students with me at Northern Virginia Community College. One of my students, Robin, observed this lovely fold, and called my attention … Read more
Tavşanlı Zone field trip, part 4
Picking up where we left off… I was telling you about the field trip I took through Turkey’s Tavşanlı Zone, a tectonic suture zone between fragments of continental crust that accreted during the closure of the Tethys Ocean. Day 2 of the trip dawned and we broke fast, and then headed out to a bizarre … Read more