Brian Ricketts
@kiwigeolog.bsky.social
Sedimentology, geofluids, sedimentary basins, volcanoes, planets - website for eager Earth Sci students at www.geological-digressions.com 🇨🇦-🇳🇿
Shark Bay (W Aust) in Nov is warm- 30ish C but the rewards... Here, extensive sea grass meadows at Monkey Mia (the dark bands) feeding grounds for dugongs, rays, turtles, & nurseries for invertebrates, fish, all attracting sharks, dolphins, and seabirds incl pelicans & emu that wander the shore ⚒️🧪🌊
November 27, 2025 at 7:38 AM
Shark Bay (W Aust) in Nov is warm- 30ish C but the rewards... Here, extensive sea grass meadows at Monkey Mia (the dark bands) feeding grounds for dugongs, rays, turtles, & nurseries for invertebrates, fish, all attracting sharks, dolphins, and seabirds incl pelicans & emu that wander the shore ⚒️🧪🌊
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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October 29, 2025 at 2:08 AM
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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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. ⚒️🧪🌊
October 9, 2025 at 11:39 PM
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. ⚒️🧪🌊
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
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). ⚒️🧪
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
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 ⚒️🧪
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
Front-yard spring! A cascade of colour, bird-song, and the odour of dung-spreading from nearby farms. ⚒️🧪😁
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 ⚒️🧪
September 15, 2025 at 4:51 AM
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 ⚒️🧪
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...
www.geological-digressions.com/elizabeth-ph...
September 1, 2025 at 4:13 AM
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...
www.geological-digressions.com/elizabeth-ph...
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
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). ⚒️🧪🌊
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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July 29, 2025 at 9:20 PM
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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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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Paratrophon (left), and lots of small barnacles. Coromandel, NZ
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July 29, 2025 at 8:12 AM
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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Paratrophon (left), and lots of small barnacles. Coromandel, NZ
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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: Type 2 variety. Arrows = flow directions. Credits NASA/JPL-Caltech/MSSS
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July 17, 2025 at 4:50 AM
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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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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July 8, 2025 at 8:22 PM
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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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
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 ⚒️🧪🌊
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
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... ⚒️🧪🌊
From the Mid-Jurassic (Bowser Basin, British Columbia) thin section image of scaphopod shell X-section w geopetal mud infill (top to right). Original shell laminae still visible. Some neomorphism of calcite in the main shell. Geopetal void is lined by isopachous calcite. Left PPL, Right X polars
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May 28, 2025 at 8:24 PM
From the Mid-Jurassic (Bowser Basin, British Columbia) thin section image of scaphopod shell X-section w geopetal mud infill (top to right). Original shell laminae still visible. Some neomorphism of calcite in the main shell. Geopetal void is lined by isopachous calcite. Left PPL, Right X polars
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My kids joke about my taking them to the beach to look at dynamic microcosms like this - fan delta progression during base-level (tide) fall (1 is oldest), channel incision, and forced regression. Image is about a metre wide. I mean - what could be more fun? ⚒️🧪🌊
May 13, 2025 at 9:24 AM
My kids joke about my taking them to the beach to look at dynamic microcosms like this - fan delta progression during base-level (tide) fall (1 is oldest), channel incision, and forced regression. Image is about a metre wide. I mean - what could be more fun? ⚒️🧪🌊
This is what happens when a bunch of local South Auckland residents argue that a once verdant estuarine mangrove forest was unsightly - perhaps they prefer views of blackened stumps and mud ⚒️🧪🌊
May 8, 2025 at 8:33 PM
This is what happens when a bunch of local South Auckland residents argue that a once verdant estuarine mangrove forest was unsightly - perhaps they prefer views of blackened stumps and mud ⚒️🧪🌊
Thin section image of Hawaiian beachrock - cross-section of a small gastropod partly filled by fibrous aragonite cement. Shell wall is layered - the thickest layer is radial calcite-aragonite crystal structure. Its neighbour (right) is a foraminifera. Plane polarized light ⚒️🧪🌊
May 2, 2025 at 12:13 AM
Thin section image of Hawaiian beachrock - cross-section of a small gastropod partly filled by fibrous aragonite cement. Shell wall is layered - the thickest layer is radial calcite-aragonite crystal structure. Its neighbour (right) is a foraminifera. Plane polarized light ⚒️🧪🌊
Things to find on a sandy beach (NZ) - gastropods, bivalves, bryozoa, barnacles, fish, sponges, the internal shells of Ram's Horn squid (Cephalopod), crustaceans, seaweed - and the inevitable plastic ⚒️🧪🌊
April 30, 2025 at 8:33 PM
Things to find on a sandy beach (NZ) - gastropods, bivalves, bryozoa, barnacles, fish, sponges, the internal shells of Ram's Horn squid (Cephalopod), crustaceans, seaweed - and the inevitable plastic ⚒️🧪🌊
Bouldery pocket beach and two sea stacks, east coast Coromandel, NZ. The near stack is very coarse lahar conglomerate, the far stack a jointed andesitic dyke. Taken just before Cyclone Tam hit, early April. The boulders moved a great deal during the storm surge ⚒️🧪🌊
April 28, 2025 at 8:00 AM
Bouldery pocket beach and two sea stacks, east coast Coromandel, NZ. The near stack is very coarse lahar conglomerate, the far stack a jointed andesitic dyke. Taken just before Cyclone Tam hit, early April. The boulders moved a great deal during the storm surge ⚒️🧪🌊
The story of Mary Mantell, one of the 19th C hidden figures who found the 1st Iguanodon tooth (~1819-1822) is either lauded, or disputed as quaint and fictitious. Discovery of an 1887 newspaper article serves to resurrect her role in the discovery ⚒️🧪
www.geological-digressions.com/mary-ann-man...
www.geological-digressions.com/mary-ann-man...
April 23, 2025 at 2:45 AM
The story of Mary Mantell, one of the 19th C hidden figures who found the 1st Iguanodon tooth (~1819-1822) is either lauded, or disputed as quaint and fictitious. Discovery of an 1887 newspaper article serves to resurrect her role in the discovery ⚒️🧪
www.geological-digressions.com/mary-ann-man...
www.geological-digressions.com/mary-ann-man...
April 21, 2025 at 8:28 PM
The aftermath of some past storm. Subject to the vagaries of time and tide.
All the textures and colours in this once vibrant root system, set against the constantly shifting sands; wave-washed ⚒️🧪🌊
All the textures and colours in this once vibrant root system, set against the constantly shifting sands; wave-washed ⚒️🧪🌊
April 18, 2025 at 6:13 AM
The aftermath of some past storm. Subject to the vagaries of time and tide.
All the textures and colours in this once vibrant root system, set against the constantly shifting sands; wave-washed ⚒️🧪🌊
All the textures and colours in this once vibrant root system, set against the constantly shifting sands; wave-washed ⚒️🧪🌊
Sand deflation on a wind-swept beach at the start of tropical cyclone Tam, April 16, east coast Coromandel, NZ. Couldn't get anywhere near this beach during the height of the storm ⚒️🧪🌊
April 18, 2025 at 1:52 AM
Sand deflation on a wind-swept beach at the start of tropical cyclone Tam, April 16, east coast Coromandel, NZ. Couldn't get anywhere near this beach during the height of the storm ⚒️🧪🌊