gigapan

The stromatolites of Helen Lake 2: GigaPans

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Posted this morning as my “Christmas gift” to blog readers in both photo and GigaPan form, here are the exquisite stromatolites of Helen Lake, Banff National Park, Alberta. link link link link link link link Finally, three other non-stromatolitic GigaPans from the site: One of Artomys Formation siltstone / shale interbeds… link …and two of … Read more

Digitate stromatolites

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Want to see something cool? Itty bitty stromatolites… like baby’s fingers! There’s a big weathered-out stylolite at the base of this stromatolite-bearing layer, too.   These elfin stromatolites are part of the boulder in the lower left (foreground) of this GigaPan, taken at the Icefields Center parking area in Jasper National Park, Alberta: link

Friday Fold: Mist Mountain Formation in Canmore, Alberta

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Let’s journey to the Cretaceous today, to see sandstones, shales, and even some coal strata that have been folded during the eastward thrusting that built the Canadian Rockies. Here’s the same fold, in context, shot in GigaPan on a different day, from a different angle. Can you match it up? link Ben Gadd showed me … Read more

Fault breccia in the Helderberg Group, Corridor H

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Here’s a breccia that Dan Doctor and I found in a tabular zone within the Helderberg Group (Devonian limestones) in one of the massive new roadcuts along Corridor H. link Is it a fault breccia or a sedimentary breccia? The breccia was bedding parallel, which suggests it could be just another bed, but it’s so … Read more

Pemaquid Point, Maine

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Pemaquid Point, Maine, is a locally-owned and -managed park near an old lighthouse. I went there yesterday with my family. We’re on vacation in coastal Maine for a week. At Pemaquid Point, the action of waves have cleaned the rocks, and they offer a delightful three-dimensional look at Acadian-aged metamorphics and granite pegmatite dikes, with … Read more

Weathering on Old Rag Mountain 2: Opferkessel

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Yesterday, I pointed out an example of differential weathering on Old Rag Mountain, in Shenandoah National Park, in Virginia. Today, I’d like to shine the spotlight on another example of weathering to be seen along the trail there: little weathering pits that occur on the top of the granite outcrops. These are opferkessel. Some people … Read more

Carbonate mudcracks in cross-section (Tonoloway Formation)

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While on Corridor H 2 weeks ago with Alan Pitts, we stopped astride the Patterson Creek Mountain Anticline, with extensive road cuts displaying Tonoloway Formation overlying Wills Creek Formation. We love this spot for its lovely folds and halite casts. See what I mean? link link This time, however, my eye was drawn to the … Read more

Stylolite from the Helderberg Group, exposed on Corridor H

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While out on the Corridor H field trip last week before the heavy snow, I found this squeal-inducingly-lovely example of a stylolite in Helderberg Group limestones (Devonian passive margin carbonates): The stylolite is a pressure-solution surface, made especially apparent in this example because of the starkly different grain sizes and colors on either side of … Read more

Antietam Formation breccia with Fe/Mn oxide cement: 2 GigaPans

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One of the intriguing rocks you find in Virginia, at the interface between the Valley and Ridge province and the Blue Ridge province, is distinctive brecciated Antietam Formation. The Antietam (sometimes known as the “Erwin,” especially in Shenandoah National Park), is a quartz arenite (quartz sandstone) that has been variably fused to quartzite in some … Read more