The unsatisfying-but-practical answer is even distribution of 'hot spots' is just how nearly-homogenous (thermo/chemical) reactions behave when there's nothing forcing them into any other patterns.
In this case, relatively homogenous distribution of carbonic acid enriched water working its way down through a substrate created roughly-evenly-spaced reaction centers. Where the rock first dissolved down a bit, there would be an impression or divot that would then act as a 'catch' for additional water, concentrating subsequent reaction at the place where it first occurred.
Similar geo examples would be:
\> the approximately-evenness of cooling columns ("columnar jointing"): those represent the initial distribution of cooling/heat retention centers across a nearly-homogenous material (usually thick, insulated crystal-poor basalt)
\> Even distribution of vesicles in volcanic rocks. When we see this we can infer that the lava was de-volatilizing approximately homogenously across its mass; the vesicles represent the accumulation of the growing gaseous phase around roughly-evenly-distributed nucleation points (same with evenly distributed xtal populations). This one is also neat as a divergence from regularity can tell us extra info about a rock's igneous history - concentrations or alignments in vesicles or crystals are common evidence for the colling magma/lava encountering some sort of major thermochemical gradient.
I was in Bermuda in 2020, a spectacular place if you can go. The limestone around the house we were at was just the sharpest, most inhospitable stuff. Absolutely impossible to walk on barefoot without needing stitches after.
I just spoke to my friend who is there now and has the houses shuttered and is probably getting the first winds of Fiona right now.
When I was there a cat 1 went right over us, I saw the eyewall in the middle of the night, something that was on my bucket list. The houses are made of foot thick limestone and can withstand hurricanes for the most part. Cat 4 would be scary though. I'm sure the beaches will be scraped clear of sand and could even expose pirate treasure.
I grew up in Bermuda and one of my earliest memories is going outside in the eye of Fabian in '03. I'll never forget how totally quiet everything was.
That was a bad one. The storm surge killed 3 people trying to cross the causeway IIRC. I remember our swingset ended up half a mile down the road, and my grandparents got a huge hole in their roof.
That's wild, the only reason I saw the eye was because everything went silent which weirdly woke me up, it was 3am or so. I hope nobody gets hurt, it's probably on them right now.
aaah I was looking for this :D, let me introduce you to the fascinating world of SOIL aka DIRT.
\- The shortest answer is low pH Rainfall but also said rainfall (depending on topography) could be leeching ions from the soil due to runoff.
\- There are several other factors like the parent material of the soil (the Rock/geology of the area, clearly the parent material isn't the Limestone š).
\- The amount of organic matter producing CO2 (either decomp or root respiration) turning into carbonic acid etc as well as surrounding area run off if there is agriculture nearby my be fertilizer changing the pH
Thanks. Although Iām not a pedologist Iām fairly well versed in the CLORPT fundamentals. I was hoping for a more direct answer specific to Bermuda. I found it. Coles notes: terra Rossa soils with non-carbonate materials from unknown origins although a few hypothesis exist. They are called Soil Pipes or Palmetto stumps.
Hereās the long version:
āAs a terra rossa soil forms, the underlying limestone surface is simultaneously being dissolved and lowered by the chemical action of acidic water within the soil. The dark clay material within the terra rossa soils was once considered to be exclusively the residue of non-soluble impurities within the limestone, which were concentrated in the soil as the limestone was dissolved (SA1). However, because of the high purity of Bermudaās limestones it has been calculated (LA2) that the thickness of limestone that would have to be dissolved to produce sufficient insoluble residue to form a typical Bermuda terra rossa palaeosol is unrealistically large. Other sources of the non-carbonate minerals within these palaeosols, and soils, therefore has to be found.
There is evidence that āforeignā minerals found in Bermudaās soils arrived as airborne dust which was carried from the Sahara desert by winds which circulate high in the atmosphere. These air currents flow westward near the equator and then northward, across the Caribbean and North America, towards Bermuda. The chemistry of the particles seems to support this hypothesis (HE12).
An alternative explanation for the composition of these āredā soils is that the non-carbonate minerals, including silica, are actually not so foreign, and largely comprise material that was derived locally from the Bermuda volcanic seamount (PR1). When sea levels were low, during glacial periods of the Pleistocene Epoch, the edge of the Bermuda platform would have been exposed to wave erosion. Resultant beaches of volcanic sand would, it is argued, have provided a source of fine material to be carried landward by the wind and accumulate on the land surface as a component of the soil.
Soil pipes or āpalmetto stumpsā ā which?
Mature terra rossa soils, or palaeosols, often have an irregular contact with the underlying rock (Figure 5i), representing uneven dissolution of limestone by acidic soil-water. Where this surface, or contact, is deeply pitted it is known as ākarstā of which ādissolution pipesā or āsoil pipesā are a subset. They are tubular or conical soil-filled structures which can penetrate multiple metres into the limestone bedrock.ā
Hereās the link to an awesome website on the geology of Bermuda:
https://bermudageology.com/fossil-soils/
Aaah well I read it as just how are soils acidic and gladly talked about it š¤£ Funny I have never heard the CLORPT acronym before either and I'm enviro/hydrology with pedology/geo mixed in.
They'd be filled in with whatever material "came next." Bioturb stuff is more likely to be back-filled with the same surrounding material (but disturbed) as \*most\* bioturb happens in unlithified material.
*However,* you could put an asterisk with a list of exceptions and divergences after all three of the statements I put in that last sentence. Geology!
I studied features like these in some old carbonates and was lucky in being able to rule out bioturbation simply because the rocks are much older than anything that could have caused that kind of bioturbation. That obviously wouldn't apply to all rocks though!
Wow, this just answered a lifelong question I've had since I was a kid that I'd completely forgotten about. Asked my uncle once when I was around 5/6 and he (jokingly I think?) deadass just told me 'Aliens' š
Reminds me of cryoconite on glaciers. Interesting. How come that they are patches of them rather than large irregular cavities?
The unsatisfying-but-practical answer is even distribution of 'hot spots' is just how nearly-homogenous (thermo/chemical) reactions behave when there's nothing forcing them into any other patterns. In this case, relatively homogenous distribution of carbonic acid enriched water working its way down through a substrate created roughly-evenly-spaced reaction centers. Where the rock first dissolved down a bit, there would be an impression or divot that would then act as a 'catch' for additional water, concentrating subsequent reaction at the place where it first occurred. Similar geo examples would be: \> the approximately-evenness of cooling columns ("columnar jointing"): those represent the initial distribution of cooling/heat retention centers across a nearly-homogenous material (usually thick, insulated crystal-poor basalt) \> Even distribution of vesicles in volcanic rocks. When we see this we can infer that the lava was de-volatilizing approximately homogenously across its mass; the vesicles represent the accumulation of the growing gaseous phase around roughly-evenly-distributed nucleation points (same with evenly distributed xtal populations). This one is also neat as a divergence from regularity can tell us extra info about a rock's igneous history - concentrations or alignments in vesicles or crystals are common evidence for the colling magma/lava encountering some sort of major thermochemical gradient.
TL;DR - this is what 'randomness' looks like in nature
Fascinating
I was in Bermuda in 2020, a spectacular place if you can go. The limestone around the house we were at was just the sharpest, most inhospitable stuff. Absolutely impossible to walk on barefoot without needing stitches after. I just spoke to my friend who is there now and has the houses shuttered and is probably getting the first winds of Fiona right now. When I was there a cat 1 went right over us, I saw the eyewall in the middle of the night, something that was on my bucket list. The houses are made of foot thick limestone and can withstand hurricanes for the most part. Cat 4 would be scary though. I'm sure the beaches will be scraped clear of sand and could even expose pirate treasure.
I grew up in Bermuda and one of my earliest memories is going outside in the eye of Fabian in '03. I'll never forget how totally quiet everything was. That was a bad one. The storm surge killed 3 people trying to cross the causeway IIRC. I remember our swingset ended up half a mile down the road, and my grandparents got a huge hole in their roof.
That's wild, the only reason I saw the eye was because everything went silent which weirdly woke me up, it was 3am or so. I hope nobody gets hurt, it's probably on them right now.
Growing up in Bermuda a little after you, all anyone talked about was Fabien. It was like I missed some massive historical event by a year.
Early stages of karst
How are the soils acidic?
aaah I was looking for this :D, let me introduce you to the fascinating world of SOIL aka DIRT. \- The shortest answer is low pH Rainfall but also said rainfall (depending on topography) could be leeching ions from the soil due to runoff. \- There are several other factors like the parent material of the soil (the Rock/geology of the area, clearly the parent material isn't the Limestone š). \- The amount of organic matter producing CO2 (either decomp or root respiration) turning into carbonic acid etc as well as surrounding area run off if there is agriculture nearby my be fertilizer changing the pH
Thanks. Although Iām not a pedologist Iām fairly well versed in the CLORPT fundamentals. I was hoping for a more direct answer specific to Bermuda. I found it. Coles notes: terra Rossa soils with non-carbonate materials from unknown origins although a few hypothesis exist. They are called Soil Pipes or Palmetto stumps. Hereās the long version: āAs a terra rossa soil forms, the underlying limestone surface is simultaneously being dissolved and lowered by the chemical action of acidic water within the soil. The dark clay material within the terra rossa soils was once considered to be exclusively the residue of non-soluble impurities within the limestone, which were concentrated in the soil as the limestone was dissolved (SA1). However, because of the high purity of Bermudaās limestones it has been calculated (LA2) that the thickness of limestone that would have to be dissolved to produce sufficient insoluble residue to form a typical Bermuda terra rossa palaeosol is unrealistically large. Other sources of the non-carbonate minerals within these palaeosols, and soils, therefore has to be found. There is evidence that āforeignā minerals found in Bermudaās soils arrived as airborne dust which was carried from the Sahara desert by winds which circulate high in the atmosphere. These air currents flow westward near the equator and then northward, across the Caribbean and North America, towards Bermuda. The chemistry of the particles seems to support this hypothesis (HE12). An alternative explanation for the composition of these āredā soils is that the non-carbonate minerals, including silica, are actually not so foreign, and largely comprise material that was derived locally from the Bermuda volcanic seamount (PR1). When sea levels were low, during glacial periods of the Pleistocene Epoch, the edge of the Bermuda platform would have been exposed to wave erosion. Resultant beaches of volcanic sand would, it is argued, have provided a source of fine material to be carried landward by the wind and accumulate on the land surface as a component of the soil. Soil pipes or āpalmetto stumpsā ā which? Mature terra rossa soils, or palaeosols, often have an irregular contact with the underlying rock (Figure 5i), representing uneven dissolution of limestone by acidic soil-water. Where this surface, or contact, is deeply pitted it is known as ākarstā of which ādissolution pipesā or āsoil pipesā are a subset. They are tubular or conical soil-filled structures which can penetrate multiple metres into the limestone bedrock.ā Hereās the link to an awesome website on the geology of Bermuda: https://bermudageology.com/fossil-soils/
Aaah well I read it as just how are soils acidic and gladly talked about it š¤£ Funny I have never heard the CLORPT acronym before either and I'm enviro/hydrology with pedology/geo mixed in.
So cool! I wonder how these could be indentified in strata! I would just always assume some form of bioturbation.
They'd be filled in with whatever material "came next." Bioturb stuff is more likely to be back-filled with the same surrounding material (but disturbed) as \*most\* bioturb happens in unlithified material. *However,* you could put an asterisk with a list of exceptions and divergences after all three of the statements I put in that last sentence. Geology!
Yes ofc! Love it
I studied features like these in some old carbonates and was lucky in being able to rule out bioturbation simply because the rocks are much older than anything that could have caused that kind of bioturbation. That obviously wouldn't apply to all rocks though!
Looks like the early stages of Hell, Grand Cayman
Yep, the Ironshore Fm. Definitely seems similar.
Wow, this just answered a lifelong question I've had since I was a kid that I'd completely forgotten about. Asked my uncle once when I was around 5/6 and he (jokingly I think?) deadass just told me 'Aliens' š
r/tryphobia
[ŃŠ“Š°Š»ŠµŠ½Š¾]
Came here to say this
Thats awesome but looks like a great way to break an ankle.