Nice straight-limbed syncline in the Helderberg Group of West Virginia (Devonian limestones, mainly): Alan Pitts shot a sweet GigaPan of this outcrop which you can explore here, or you can just look at this zoomed-in detail: Aaron Barth is down there in the lower right corner for scale.
More evidence of currents in the Devonian deep… Primary structures that give us clues, preserved in a place where preservation over 360 million years isn’t necessarily guaranteed. As you might expect, this turbidity currents roared in from the east, where the mountains were rising, and generating a fair bit of sand and mud, during the … Read more
The Friday fold is found on a newly-opened section of road in West Virginia. Join Callan in checking out some synclines and associated faults in the Devonian-aged Brallier Formation.
This blog has been noticeably photo deficient lately! Time to remedy that. Today, I offer you a couple of shots of the Brallier Formation (shale / fine-grained sandstone) in West Virginia’s Valley & Ridge province, a few miles northwest of Moorefield, on the newly-opened section of New Route 55. The Brallier was deposited in a … Read more
Elizabeth Eide of the National Academies shared this image with me a year or two ago, when she gave a talk on Norwegian geology for the Geological Society of Washington. Those are some bookshelfed gneiss layers sandwiched between upper-left and lower-right carbonates. The “bookshelfing” refers to the numerous parallel brittle fractures along which the gneiss … Read more
Fellow geobloggers Brian and Eric have been getting all flutey on us lately, so I figure it’s a good time to show my best photo of flute casts: As the annotated copy suggests, this was taken on the side of the Pennsylvania Turnpike back in March 2008, when four Honors students and I drove up … Read more
Callan attends a field trip in the Blue Ridge of Virginia, looking first at a Paleozoic shear zone that disrupts (and improves) Mesoproterozoic basement complex rocks.
It seems I forgot to show this fossil when I found it in February of last year with my MSSE advisor John Graves. We were out in the Needmore Formation of the Fort Valley then. The Needmore is a formation I visited again yesterday with some colleagues in other outcrops further to the west. In … Read more
Today, you get a photo from GMU structure student Nik D. This is a small exposure in the Hampshire Formation (Devonian) on New Route 55 in West Virginia. It shows a fine example of plumose structure with the not-often-seen concentric ribs running perpendicular to the ‘plumes.’ At the edge of the joint, you can see … Read more
I took a look at some interesting blobby structures in the Swift Run Formation last week, and walked readers through my logic in tentatively concluding that they were ball & pillow structures (soft sediment deformation), though overprinted by a pervasive (Alleghanian) cleavage. As we move west in the Appalachian mountain belt, the rocks are less … Read more
We just looked at the Chilhowee Group, a package of sediments that records the transition for the North American mid-Atlantic from Iapetan rifting through to passive margin sedimentation associated with the Sauk Sea transgression. Well, if we journey a bit further west, we see the sedimentary stack isn’t done telling its story. The saga continues … Read more
Over on the far right by Chuck Bailey (yellow shirt) you can see the crescent-shaped profile of a river channel (gray color). To the left of that, you can see levee deposits, and beyond that (to the left) crevasse splay deposits and the floodplain (dark red mudstones). This is in the Hampshire Formation, part of … Read more
Here we are in the Brallier Formation, a Devonian turbidite sequence. Prominent in the middle of this photo is the Bouma “C” horizon with the cross- bedding.
This one is also from the Millboro Formation: itty bitty brachs (not too much oxygen in those depths for building up big body sizes) that have been sheared during Alleghanian deformation.
This photo is from the Millboro Formation: mostly deep water black shale, but with the occasional heavy turbidite coursing in and settling its bulk down on the squishy mud beneath. Some folks on our trip suggested these might be seismites: soft sediment deformation resulting from earthquake-induced vibration.
Where are some ripple marks in the Hampshire Formation. Cell phone service is a lot more localized here in West Virginia, so we’ll see how many posts I manage today…