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7 December 2022

The coastal section at Esterillos Oeste, Costa Rica

Callan documents a geological stroll along the coast of Esterillos Oeste, in central southern Costa Rica, investigating the sequence of sediment in the Punta Judas Formation (Mid-Miocene) exposed there. Fossils, sedimentary structure, diagenetic features, structural deformation, and modern weathering all make prominent appearances.

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28 November 2022

Getting ripped

Patterns in the sand on a beach in Costa Rica…

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27 November 2022

Book report

Callan offers reviews of a suite of good reads – some old and some new, some geology and some general science, and some social justice/history.

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11 November 2022

How the Mountains Grew, by John Dvorak

Callan reviews a recently-published book that offers “a new geological history of North America.”

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5 September 2022

Book report

Callan reviews five books, both fiction and non-. In this batch, we get Neal Stephenson’s latest techno-thriller, about geoengineering and its discontents, Barack Obama’s first memoir, a novel by Charles Dickens, a collection of short stories by Andy Weir (author of The Martian), and Bill Bryson’s sole foray into popular science writing.

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16 August 2022

Kinked metavolcanics of the Castine Formation, eastern Maine

Callan shares a few outcrops from coastal Maine, part of the Avalonia terrane that accreted to ancestral North America during the Acadian Orogeny. They are volcaniclastic rocks, coarse and fine, and showing both overprinting kink bands and cross-cutting basaltic dikes.

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15 August 2022

Book report

Five books get the Callan mini-review treatment: two novels from Amor Towles, an account of life in prison under solitary confinement, a history of Virginia slavery during the War of 1812, and finally a family account of the discovery of the fossil Hesperornis, a toothed bird, and various associated tangents.

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30 July 2022

Well-preserved mudcracks in Belt argillite, Glacier National Park, Montana

Fresh from the field, Callan shares a quintet of beautifully preserved desiccation cracks in Mesoproterozoic Belt Supergroups sediments, exposed in Montana’s geological gem, Glacier National Park.

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24 June 2022

Friday fold: Kinked Lynchburg metasediments near a soapstone body

Happy Friday! Here are some kink-folded metasediments from Virginia’s Lynchburg Group to help usher in the weekend.

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29 May 2022

Accretionary wedge turbidites from the Lost Coast

The Lost Coast of northern California shows geological evidence of deep sea turbidity current sedimentation, tectonic accretion during Mesozoic subduction, and then isostatic uplift interacting with shoreline erosion. Check out a few photographs taken by Callan’s wife on a recent backpacking trip through the region.

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