Brian Ricketts
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kiwigeolog.bsky.social
Brian Ricketts
@kiwigeolog.bsky.social
1.2K followers 640 following 360 posts
Sedimentology, geofluids, sedimentary basins, volcanoes, planets - website for eager Earth Sci students at www.geological-digressions.com 🇨🇦-🇳🇿
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kiwigeolog.bsky.social
Hannah Robertson, the little celebrated wife of David Robertson an eminent 19th C Scottish marine biologist, was accomplished in the science of modern seaweeds, conchology & foraminifera. Acknowledgements of her expertise were few #Pioneering #Women www.geological-digressions.com/hanna-robert...
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There are no photos of Hannah Robertson, so instead I add this one of modern NZ marine algae (seaweed) - the kind of thing that Hannah Robertson worked on. The seaweed garden hosts grazing gastropods, barnacles, mussels, encrusting bryozoa, and calcareous worm tubes (polychaetes)
October 29, 2025 at 2:08 AM
kiwigeolog.bsky.social
Thin section images of glauconitic pellet sand dredged from about 300 m on Chatham Rise, an elongate marine platform extending 1400 km east of South I. NZ. It is underlain by continental crust - a submerged part of Zelandia continent. Includes barnacles, foraminifera & echinoderm plates, spines. ⚒️🧪🌊
Thin section images of glauconitic pellet sand dredged from about 300 m on Chatham Rise, an elongate marine platform extending 1400 km east of South I. NZ. It is underlain by continental crust - a submerged part of Zelandia continent. Includes echinoderm plates, spines, and foraminifera.
October 9, 2025 at 11:39 PM
kiwigeolog.bsky.social
Triassic rocks (grey cliffs = sandstone + diabase) thrust over Early-Mid Eocene sandstone (foreground) along Mokka Fiord, Axel Heiberg I. (next door to Ellesmere I, N Canada). The thrust itself (at base of slope) may be through Carboniferous-Permian evaporites (mostly covered by scree). ⚒️🧪
Triassic rocks (grey cliffs = sandstone + diabase) thrust over Early-Mid Eocene sandstone (foreground) along Mokka Fiord, Axel Heiberg I. (next door to Ellesmere I, N Canada). The thrust itself (at base of slope) may be through Carboniferous-Permian evaporites (mostly covered by scree).
October 6, 2025 at 7:35 PM
kiwigeolog.bsky.social
Some delicate actively growing stalactites from Ruakuri Caves, formed in Oligocene limestones. Skinny varieties are probably few decades old; the larger a few centuries. Ruakuri is the Maori name for Two Dogs - refers to early Polynesian canines brought to NZ. On a visit w a couple of grandkids ⚒️🧪
Some delicate actively growing stalactites from Ruakuri Caves, formed in Oligocene limestones. Skinny varieties are probably few decades old; the larger a few centuries. Ruakuri is the Maori name for Two Dogs - refers to early Polynesian canines brought to NZ. On a visit w a couple of grandkids
September 29, 2025 at 10:57 PM
kiwigeolog.bsky.social
Front-yard spring! A cascade of colour, bird-song, and the odour of dung-spreading from nearby farms. ⚒️🧪😁
Front-yard spring! A cascade of colour, bird-song, and the odour of dung-spreading from nearby farms.
September 28, 2025 at 1:47 AM
kiwigeolog.bsky.social
Claudine Picardet's (1735-1820) translation of texts for scientists like Karl Scheele, Abraham Werner, Richard Kirwan (phlogiston) & maybe Lavoisier. She enabled and participated in the dissemination of 18th-19th C science to a broad audience.
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www.geological-digressions.com/claudine-pic...
Claudine Picardet (1735-1820)
Claudine Picardet's (1735-1820) translation of science texts texts enabled the dissemination of 18th-19th C science to a broad audience.
www.geological-digressions.com
September 22, 2025 at 2:02 AM
kiwigeolog.bsky.social
Weathering patterns in basalt (a boulder lodged in beach sand) where oxidation of iron-bearing minerals (mainly amphiboles and pyroxenes) was controlled by earlier formed orthogonal joints. The dark grey bits are remnant non-altered basalt. Karioi Mt. Raglan, west coast NZ ⚒️🧪
Weathering patterns in basalt (a boulder lodged in beach sand) where oxidation of iron-bearing minerals (amphiboles and pyroxenes) was controlled by earlier formed orthogonal joints. The dark grey bits are remnant non-altered basalt. Karioi Mt. Raglan, west coast NZ
September 15, 2025 at 4:51 AM
Reposted by Brian Ricketts
doktrock.bsky.social
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September 10, 2025 at 3:02 AM
kiwigeolog.bsky.social
A post I’ve been putting together for 2 years - the Etymology of Earth Sci Words. So far about 500 terms - the initial goal before clicking the ‘Publish’ tab

www.geological-digressions.com/etymology-of...

There are >1,000,000 words in the English language
So my 500 words is a paltry sample. ⚒️🧪🌊
Etymology of Earth science words and phrases
The origins of words, prefixes, suffixes, abbreviations, names, acronyms, and terms commonly used in Earth sciences.
www.geological-digressions.com
September 8, 2025 at 2:40 AM
kiwigeolog.bsky.social
I've been reluctant to post the 'Glossary of planetary geology' in my website, to the Astro & #planetsci feeds - because I'm an interloper in those fields, an Earth-bound geologist
The rationale - I'm fascinated by it all

There are 500 entries 🔭 ⚒️
www.geological-digressions.com/glossary-of-...
Glossary of planetary geology
Glossary of planetary geology, the Solar System, moons, asteroids, comets, meteorites, exploration, and related terminology
www.geological-digressions.com
September 4, 2025 at 4:17 AM
kiwigeolog.bsky.social
The 2nd post - Expt Results.
The expt is a good eg. of the sophistication now possible with physical, stratigraphic and sedimentologic modeling. Chris Paola, one of the creators of the XES facility, generously provided copies of the images used here.⚒️🧪
www.geological-digressions.com/experimental...
Experimental sequence stratigraphy:  model results
Description of an experiment (Martin et al.,.2009) that evaluates geometry & chronostratigraphic significance of sequence stratigraphic surfaces in a scale-independent model where only base level chan...
www.geological-digressions.com
September 3, 2025 at 12:12 AM
kiwigeolog.bsky.social
More on geological modeling for students, 2 posts on a scale-independent stratigraphy experiment using the XES facility at St. Anthony Falls Lab, Minnesota U- the 1st model to incorporate variable subsidence
1st post - methods & boundary conditions ⚒️🧪 www.geological-digressions.com/experimental...
Experimental sequence stratigraphy:  model attributes
This post describes the experiment methods and boundary conditions of a scale-independent, experimental stratigraphic model
www.geological-digressions.com
September 3, 2025 at 12:08 AM
kiwigeolog.bsky.social
Elizabeth Philpot was an important participant in the late 18th and 19th C development of paleontology and geology, a collaborator with Mary Anning, Louis Agassiz, Henry De la Beche, William Buckland, and others. The fish was one of her discoveries ⚒️🧪🌊
www.geological-digressions.com/elizabeth-ph...
Elizabeth Philpot was an important participant in the late 18th and 19th C development of paleontology and geology, a collaborator with Mary Anning, Louis Agassiz, Henry De la Beche, William Buckland, and others. The fish was one of her discoveries
September 1, 2025 at 4:13 AM
kiwigeolog.bsky.social
Sponge spicules, composed of silica, in thin section. The ornate end structures are used to attach one spicule to another to form an internal skeleton that is flexible enough to sway and bend in flowing water (from Three Kings Islands seafloor, northernmost NZ). ⚒️🧪🌊
Sponge spicules, composed of silica, in thin section. The ornate end structures are used to attach one spicule to another to form an internal skeleton that is flexible enough to sway and bend in flowing water (from Three Kings Islands seafloor, northernmost NZ).
August 13, 2025 at 12:07 AM
kiwigeolog.bsky.social
Here's a nice Oligocene temperate water limestone photomicrograph from NZ, in PPL, with a glauconite-filled benthic foram, lots of bryozoa, some barnacle plates, echinoderm spines & plates, & the odd bivalve or gastropod fragment, all set in drusy calcite cement. Bar scale is 200 microns.
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Here's a nice Oligocene temperate water limestone photomicrograph from NZ, in PPL, with a glauconite-filled benthic foram, lots of bryozoa, some barnacle plates, echinoderm spines & plates, & the odd bivalve or gastropod fragment, all set in drusy calcite cement. Bar scale is 200 microns.
July 29, 2025 at 9:20 PM
kiwigeolog.bsky.social
Rocky intertidal life: a tangled web of calcareous serpulid worms (Pomatoceros) draped by the branched brown alga Xiphophora(?) A couple of snails nestling in crevasses (Cominella I think - top-bottom centre), a couple of grazing
Paratrophon (left), and lots of small barnacles. Coromandel, NZ
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Rocky intertidal life: a tangled web of calcareous serpulid worms (Pomatoceros) draped by the branched brown alga Xiphophora(?) A couple of snails nestling in crevasses (Cominella I think - top-bottom centre), a couple of grazing snails Paratrophon (left), and lots of small barnacles. Coromandel, NZ
July 29, 2025 at 8:12 AM
kiwigeolog.bsky.social
Another Pioneering Woman in Earth Science. Charlotte Murchison was an active collaborator and the intellectual equal and force behind her husband Roderick's scientific success. Also a friend of Mary Anning.
www.geological-digressions.com/charlotte-mu...
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Charlotte Murchison (1788-1869)
Charlotte Murchison was an active collaborator and the intellectual equal and force behind her husband Roderick's scientific success
www.geological-digressions.com
July 23, 2025 at 9:18 AM
kiwigeolog.bsky.social
Very nice climbing ripples from Gale crater - 305 million km away. Left: Out of phase (type 2) in lower half, In-phase (P) in upper section indicate a change in flow and proportions of suspended sediment load. Right: Type 2 variety. Arrows = flow directions. Credits NASA/JPL-Caltech/MSSS
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Very nice climbing ripples from Gale crater - 305 million km away. Left: Out of phase (type 2) in lower half, In-phase (P) in upper section indicate a change in flow and proportions of suspended sediment load. Right: Mostly the Type 2 variety. Arrows = flow directions. Credits NASA/JPL-Caltech/MSSS
July 17, 2025 at 4:50 AM
kiwigeolog.bsky.social
A look at the sedimentary rocks on Mars that require flowing fluids. Focuses on bedload transport (of loose sediment) to form crossbeds - recognition of these structures provides clues to the former presence of fluids, particularly water.
www.geological-digressions.com/evidence-for...
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Evidence for bedload deposition on Mars
Why focus on bedload deposition? Because it provides evidence for fluids (air-water) on the ancient Martian surface
www.geological-digressions.com
July 16, 2025 at 5:08 AM
kiwigeolog.bsky.social
The recognition of lithified sediment has fundamental implications for Mars ancient history - the processes require aqueous chemical reactions. Here's a brief account of the criteria used to identify these rocks
www.geological-digressions.com/evidence-for...
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Evidence for sedimentary rocks on Mars
Presence of sedimentary rocks on Mars has profound consequences because water is required for the transformation from soft sediment to rock
www.geological-digressions.com
July 16, 2025 at 5:03 AM
kiwigeolog.bsky.social
Shore-lead through gypsum-halite crusts on an Atacama - Altiplano salar, northern Chile. Snow in the foreground. Eocene volcanic cone at back. Early summer - the flamingos arrived soon after this was taken. About 4000 m altitude. UV index about 50% higher than at sea level.
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Shore-lead through gypsum-halite crusts on an Atacama - Altiplano salar, northern Chile. Snow in the foreground. Eocene volcanic cone at back. Early summer - the flamingos arrived soon after this was taken. About 4000 m altitude. UV index about 50% higher than at sea level.
July 8, 2025 at 8:22 PM
kiwigeolog.bsky.social
Boulder pocket beaches between rocky headlands. Most of the larger clasts are moved only during Pacific storms. All volcanic, mostly andesite, dacite and rhyolite, West coast Coromandel, NZ ⚒️🧪🌊
Boulder pocket beaches between rocky headlands. Most of the larger clasts are moved only during Pacific storms. All volcanic, mostly andesite, dacite and rhyolite, West coast Coromandel, NZ
July 2, 2025 at 2:06 AM
kiwigeolog.bsky.social
Carlotta Maury bucked social norms as a paleontologist: a PhD by 1902, field work in southern US, Caribbean, S. Africa, and W. Europe, her own expedition to the Dominican Republic, one of the 1st women to become deeply involved in oil exploration. ⚒️🧪
www.geological-digressions.com/carlotta-mau...
Carlotta Maury (1874-1938)
Carlotta Maury bucked social norms as a paleontologist: a PhD, organized an expedition, and consulting with Royal Dutch Shell 1910-1937
www.geological-digressions.com
June 25, 2025 at 4:14 AM
kiwigeolog.bsky.social
My Earth Scientists feed is suddenly empty - anyone else? All the other feeds I follow are ok. ⚒️🧪🌊
June 24, 2025 at 3:34 AM
kiwigeolog.bsky.social
Almost 50 years since PhD field work here - east side of Tukarak, Belcher Islands, Hudson Bay. Paleoproterozoic carbonates, Holocene raised beaches. Glorious rocks and landscapes. Tent site on island slightly left centre - the small white dot. Weather was generally crap, but on days like this... ⚒️🧪🌊
Almost 50 years since PhD field work here - east side of Tukarak, Belcher Islands, Hudson Bay. Paleoproterozoic carbonates, Holocene raised beaches. Glorious rocks and landscapes. Tent site on island slightly left centre - the small white dot. Weather was generally crap, but on days like this...
June 23, 2025 at 8:33 PM