Advertisement

You are browsing the archive for quartz Archives - Mountain Beltway.

15 July 2018

Chickie’s Rock, Pennsylvania

A virtual field trip to the deformed quartzites and metaconglomerates of Chickie’s Rock and Sam Lewis State Park in Lancaster County, Pennsylvania.

Read More >>

No Comments/Trackbacks >>


23 January 2018

A kid and his slicks

On a family hike, Callan’s son finds some interesting smooth lines on a rock. What are they? What do they tell us? Tune in for a brief history of Appalachian geology.

Read More >>

5 Comments/Trackbacks >>


27 October 2017

Friday fold: Quantankerous veins

What does it mean for a vein to be “quantankerous?” Well, to start with, it’s quartz. Second, it has to be disagreeable or cantankerous. This vein, seen in meta-arkose of the Catoctin Formation near the summit of the Blue Ridge at Rockfish Gap (not Afton Mountain), is such a quantankerous individual: You’ll notice its “S” shape, which might imply top-to-the-left kinematics. But just down the outcrop is this set of …

Read More >>

2 Comments/Trackbacks >>


16 May 2016

Trace fossils in the Massanutten Sandstone

Over the weekend, my wife and I took a walk with our son at the Storybrook Trail, an accessible trail with a fine overlook to the east over the Page Valley. There, the Massanutten Sandstone shows a bunch of big beefy trace fossils at this site: both bedding-parallel (Arthophycus-like) and bedding-perpendicular (Skolithos-like) traces. Here’s Bax on a photogenic slab of the quartz arenite, showing the inch-wide bioturbation: A short distance …

Read More >>

No Comments/Trackbacks >>


3 March 2015

Ichnofossils in Gog quartzite

At the Spiral Tunnels overlook on the Trans-Canada Highway, you can look at trains. Or, you can check out some lovely trace fossils in boulders which divide the viewing area from the highway: These are in the Gog Formation, a Cambrian-aged quartz arenite, mostly fused to quartzite nowadays… I know which subject I would choose to spend my time looking at…

Read More >>

No Comments/Trackbacks >>


30 December 2014

Skolithos in Gog quartzite, on the trail to Helen Lake

Some boulders seen on the trail to Helen Lake sported lovely sets of Skolithos trace fossils. Here are two boulders, with the perspective on the tubular paleo-vertical Skolithos burrows being “map view”: Another boulder, in the middle of the trail, showed them in a fine cross-sectional view: (click to enlarge substantially) It also included some interesting “ribbed” vertical traces that I didn’t recognize as familiar: …Diplocraterion, perhaps? Seems too “linear” …

Read More >>

3 Comments/Trackbacks >>


16 December 2014

Buzzard Rocks

Back in 2011, when we were still living in D.C., Lily and I made a hiking trip out to Buzzard Rocks. It was a destination. Now that I live out here in the Fort Valley, I see Buzzard Rocks all the time, and I love it. It’s such a cool feature – a spot on the crest of the hill where you can see the slabby expression of steeply-dipping beds …

Read More >>

No Comments/Trackbacks >>


12 December 2014

Friday fold: Miette slate, Alberta

The Friday fold returns to Canada, looking at Neoproterozoic slate and quartzite at the southern terminus of the Icefields Parkway. Bonus features include ripple marks, graded beds, cross-bedding, cleavage, and boudinage.

Read More >>

No Comments/Trackbacks >>


5 March 2014

Oriskany Formation quartz arenite and its fossils, Corridor H

Today, a few more photos from the field trip last month to Corridor H, the fine new superhighway with so little traffic out in eastern West Virginia. Our antepenultimate stop of the day was at an outcrop we inferred should hold the Oriskany Sandstone, a Devonian quartz arenite that lies stratigraphically above the Helderberg Group limestones and below the Needmore Shale. We were using Lynn Fichter’s indispensible stratigraphic column for …

Read More >>

3 Comments/Trackbacks >>


6 June 2013

Percussion marks on quartzite cobbles in DC

Hey, that quartzite boulder has measles! Or is it bubonic plague? Or maybe it’s just acne? Look closer and see if you can deduce what these things are: These conical fractures are percussion marks. They form when a cobble smacks into another cobble underwater, propelled forward by a powerful current. As the two rocks knock together, the strength of the collision can overwhelm the strength of the bonds holding the …

Read More >>

No Comments/Trackbacks >>