Concretions in the Millboro Formation, Fort Valley
Some enormous concretions are encountered in a shale quarry in the central Fort Valley. Concretions like these are typical of the Devonian-aged Millboro Formation.
concretions
Variably-cemented conglomerate – a virtual sample
Here’s another example of a visualization combination that leverages the advantages of the GIGAmacro system with the 3D ‘virtual sample’ perspective of the Sketchfab-hosted model: the same sample presented in both formats. In this case, it’s a lovely example of a conglomerate that I found in our lab at NOVA, showing variations in the level … Read more
This week’s batch of 3D models
Anorthosite with lovely garnet reaction rims, a spherical hematite concretion, and some sweet breccia. Check them out and explore!
Millboro Formation shale in outcrop and in hand sample
Another site from the GMU sedimentology field trip in April: An outcrop on Route 33 in Brandywine, West Virginia, showing the Millboro Formation. It’s mostly shale, with some intriguing sandstones, too. There are fossils and diagenetic carbonate nodules (concretions). Here’s the outcrop, the largest GigaPan I’ve taken so far (7.9 billion pixels): [gigapan id=”171447″] link … Read more
More oncoids (from the Peyto Formation?)
Two years ago, I posted on some interesting structures my students and I saw at Consolation Lakes, near Moraine Lake in Banff National Park. They were little concretions, “oncoids” roughly speaking, and may have indicated (thanks Howard!) that the boulders were sourced to the Peyto Formation, a Cambrian carbonate within the Gog group: The purpose … Read more
Morning with the local expert
Royal Tyrrell Museum geologist Dave Eberth donates time and expertise to help Callan’s students understand the Cretaceous-aged Horseshoe Canyon Formation in central Alberta.
Orange oncolites from Consolation Lakes
Callan presents a mystery rock found in blocks of sedimentary rock on a talus slope near the Consolation Lakes in Banff National Park, Alberta. Are they orange oncolites? Or alien embryos? 🙂
More moki marbles
More moki marbles: little concretions in sandstone, kind of like the ones I showed you Tuesday from Illinois. But these ones are from the Navajo Sandstone, a late Triassic or early Jurassic erg deposit from the Colorado Plateau. These photos were taken in Zion National Park, near Springdale, Utah (real close to the cross-beds I … Read more
Giant City State Park, Illinois
Giant City State Park is a patch of protected forest south of Carbondale, Illinois, where there are some pretty cool exposures of Pennsylvanian-aged Makanda Sandstone. Here’s a typical look at one: Notice the deep chasm on the right. This leads, maze-like, to other flat-bottomed and vertically-walled canyons: The orthogonal joint sets produces some nice tall, … Read more
Split concretion
Concentrically-zoned ironstone concretion in sandstone of the Morrison Formation, eastern flank of the Bighorn Mountains / western edge of the Powder River Basin, Wyoming, at the Sheridan College dinosaur fossil quarry, last week. The white stuff is caliche. A quick post to celebrate the fact that as of three hours ago, Lily & I are … Read more