Refuting Creationism - Scientists Discover What Caused Earth's Climate Cycle To Change A million Years Before 'Creation Week'

Rig used for obtaining core samples of seabed sediment

The pattern of glaciation and warmer spells changed about 1,000,000 years ago.

Deep ocean clues to a million-year-old Ice Age puzzle revealed in new study – Woods Hole Oceanographic Institution

Like almost all of Earth's history, a sudden change in the cyclic pattern of climate change occurred in that long, pre-Creation period. To be precise, 700,000 to 1 million years ago the pattern of glaciation and interglacial warm spells changed from a 41,000 year cycle, due to changes in the degree of tilt in Earth's rotation (axial precession), to one of about 100,000 years with no obvious change in axial precession or external causes such as solar radiation. This is known to climatologists and geologists as the Mid-Pleistocene Transition (MPT)

Given the conviction of creationists that their putative designer god created Earth perfectly tuned for them to live on, it will probably be disturbing to learn that Earth's pattern of climate can change radically over the long term, and not caused by anthropogenic increases in greenhouse gases but by perfectly natural processes that don't need the interference of a magic deity to explain them. On top of this all happening before they believe Earth was created out of nothing as a small flat planet with a dome over it, there is much here for creationists to ignore and for their cult to lie about.

Refuting Creationism - How The Grand Canyon Reveals Life On Earth 540 Million Years Before 'Creation Week',

Professor Carol Dehler samples the 500-million-year-old Bright Angel Formation in the Grand Canyon.

Photo: UNM/Laura Crossey

The Grand Canyon's Horseshoe Bend, where creationisst believe a raging torrent of flood water did a 180 degree turn and headed back the way it came.

USU Geologist, Colleagues Rewrite Textbooks With New Insights From Bottom of the Grand Canyon

The Grand Canyon often features in creationist disinformation websites because it needs to be explained away in terms of a history of Earth lasting only some 6-10,000 years and because it is easy to fool people who want to be fooled that it is somehow evidence if a global flood, and in particular how the water in the alleged flood ran away. Cult frauds also pretend the different rock layers in the canyon wall can all be explained in terms of sediment deposited during their god's supposed genocidal flood.

The truth, as usual with creationist claims, is nothing like the childish myth they like to pretend is real history. In fact, the walls of the Grand Canyon are a record of plate tectonics and climate change over hundreds of millions of years and mesh completely with what is known of Earth's history from other sources.

An indication of how creationists cult leaders are terrified of the information in the walls of the Grand Canyon, can be gauged from the notorious creationist purveyor of disinformation, Andrew Snelling's article on the creationists disinformation site, Answers in Genesis and the lengths he went to to obtain sample without disclosing exactly where he got them from, as related in this article in science. Snelling argued that it discriminated against his religion to require him to provide GPS coordinates of his samples! Clearly, Snelling believes his religion requires his 'science' to lack precision and reproducibility in case someone else tried to replicate his measurements and finds his to be bogus.

Snelling was subsequently given permission to collect samples under supervision and then wrote up his findings to try to explain away the fact that his findings didn't conform to his YEC preconceptions. His excuses include the creationists go-to excuse - the unsubstantiated claim that the uniformly old age of the rock he obtained must be because radioactive decay rates used to be different by several orders of magnitude!
One of Snellings stated objectives was to prove that the deformed Tapeats sandstone deposits, which he assures his readers are not fractured, despite the fact that photographs show fractures, were soft when deformed. He mentions this early in his article but then quietly drops the subject, presumably because his findings contradict his claim.

His findings are soundly refuted here.

Clearly, it is important to creationist cult leaders that their dupes are badly misinformed about the date of the rocks in the walls of the Grand Canyon, and it is obvious why, as this paper by geologists from Utah State University, together with colleagues from the University of New Mexico, Boise State University, Idaho, the University of Las Vegas, Nevada and the Denver Museum of Nature & Science, Denver, Colorado, shows. The rocks at the bottom of the canyon are from the Cambrian, 540 million years before creationists dogma says Earth was made from nothing by magic.

Other rocks map exactly onto what is known of changes in sea level and climate due to plate tectonics and how the canyon itself was carved into those strata is fully explainable in terms of erosion by a river flowing over a river bed that was rising slowly due to forces beneath Earth's crust over a period of millions of years.

Perhaps the most embarrassing thing for creationists is the thing they normally avoid like the plague - the famous Horseshoe bend, which requires their credulous dupes to believe a raging torrent of water, for no apparent reason, changed direction by over 180 degrees and headed back the way it came, when raging torrents of water are notoriously uni-directional.

And why on Earth anyone would imagine the water from a global flood would flow through a canyon in the middle of North America into the Pacific Ocean is anyone's guess and not something Andrew Snelling or any other creationist apologist has ever attempted to explain, simply leaving it to their parochial and culturally chauvinistic dupes to assume that anything important that happened in world history must have happened in the USA.

Refuting Creationism - What Happened When a Massive Metor Hit Earth 3 billion Years Before 'Creation Week'

Impression of a massive impact 3.26 billion years ago

AI-generated (ChatGPT4o)

What happened when giant S2 meteor hit Earth 3 billion years ago?— Harvard Gazette

Barberton Greenstone belt of South Africa.

Photo: Nadja Drabon

Creationists love to tell us how their putative intelligent designer designed an entire Universe with countless trillions of stars many with planetary systems, and made a special one called Earth which is perfectly designed for them to live on.

The problem with that comforting lie is that it isn't borne out by the disturbing truth. Not only is Earth far from perfect for their (human) life over most of its area, being inaccessible and hostile without special human-made technology, but it has been, and probably will be again, subject to almost unimaginable, catastrophic events in its past, such as plate tectonics causing changes in ocean currents which caused climate change so drastic the Earth literally froze over. There have equally been times when the polar icecaps melted flooding coastal areas where many of our modern major cities and ports are located.

Refuting Creationism - Walking With Dinosaurs 70-75 Million Years Before 'Creation Week'

Artist's depiction of H. piceanus in a Late Cretaceous swamp.

Illustration by Brian Engh
LivingRelicProductions.com

Paleontologists discover Colorado ‘swamp dweller’ that lived alongside dinosaurs | CU Boulder Today | University of Colorado Boulder

Paleontologists dig for fossils in northwestern Colorado.

Credit: John and ReBecca Foster.

AI-Generated illustration of life in a Cretaceous swamp near the Western Inland Seaway

ChatGPT4o

For some reason creationists have a fixation with dinosaurs, probably because, deep down, they know their existence refutes the biblical nonsense of an Earth that's only 6-10,000 years old. After all, there is nothing quite like a 75 million-year-old fossil of a living creature for falsifying the idea that the Universe, Earth and life on it were all created in a single week, just a few thousand years ago.

So, their cult leaders are forever scraping around trying to find evidence that human beings and dinosaurs lived together and even that Jesus would have been familiar with T. rex or Diplodocus and was probably used to pterosaurs flying overhead. But of course, there is none - which was never a reason for a creationist to abandon a delusion.

What there is, however, is evidence that dinosaurs were around until about 66 million years ago then promptly went extinct to be replaced by birds and mammals as the dominant terrestrial life forms.

And now we have evidence of an early mammal living amongst dinosaurs in what if now Colorado, USA. Sadly, there is no evidence that the early mammal resembled Jesus or any other humans for that matter; it was more like a muskrat.

Refuting Creationism - Humans Were Butchering Elephants In India 300-400,000 Years Before 'Creation Week'

The elephant skull being excavated from the quarry in Kashmir in 2000.

Photo: Advait Jukar

Rare fossils of extinct elephant document the earliest known instance of butchery in India – Research News

Having taken a short break from writing blog posts to work on a new book, I'm now taking a short break from writing a book to catch up on an accumulation of papers that refute creationism, not intentionally (few serious working scientists bother to do that nowadays) but quite incidentally by simply revealing facts that are entirely inconsistent with creationist dogmas.

This news release, for example, exposes the fact that there were humans butchering elephants in India between 300,000 and 400,000 years ago in that 99.9975% of Earth's history that happened before creationists believe there was even an Earth for people and elephants to live on.

The evidence is the cut marks on the remains of a three extinct giant elephants, Palaeoloxodon turkmenicus, which died near a river at what is now Pampore in the Kashmir Valley. Soon after they died, they were covered in sediment and buried along with 87 stone tools that had been used to butcher them along with the bone flakes that show the bones were struck in exactly the right way to extract the marrow. The butchers clearly knew what they were doing.

Refuting Creationism - Ancient Deluges - In Australia, 90,000 years Before 'Creation Week'

Pinnacles at Nambung National Park

Picture: Matej Lipar

Pinnacles at Nambung National Park

Iron nuggets in the Pinnacles unlock secrets of ancient and future climates - News at Curtin | Curtin University, Perth, Australia

For another o todays casual and incidental refutations of creationism, we have news about the climate in Western Australia, 90,000 years before creationists little god magicked up a small flat planet with a dome over it, according to the book of Bronze Age creation myths that creationists have mistaken for a science textbook.

Of course, when everything else about Earth's history occurred in the 99.9975% of its history that occurred before the mythical 'Creation Week', this will come as no surprise to anyone who is not functionally illiterate with the thinking ability of a slow 9year-old.

Refuting Creationism - Living Bacteria Sealed Inside 2 Billion-Year-Old Rock

Microbial cells stained green

© Y. Suzuki, S. J. Webb, M. Kouduka et al. 2024/ Microbial Ecology

2-billion-year-old rock home to living microbes | The University of Tokyo

The Bushveld Igneous Complex (BIC), South Africa.
This picture shows a very famous outcrop where nearly horizontal black and white layers are observed. The BIC made of layers of igneous rock in a basin shape, formed over a period of about 1 million years, after which it seems to have barely changed.

© Y. Suzuki.

In today's incidental rebuttal of creationist dogma, archaeologists have discovered living colonies of microbes sealed within cracks in 2-billion-year-old rocks from South Africa.

The microbes became sealed in the cracks by tightly-packed layers of clay so effectively creating sealed chambers from which nothing could escape and, more importantly, nothing could enter. They have survived over geological time by firstly having an extremely low metabolic rate, with a generation time measured in thousands, even millions of years, compared to surface-dwelling microbes with generation times in hours or minutes, and by utilising sulphates as their energy source.

What they demonstrate, apart from the fallacy of Earth only being made by magic 10,000 years ago, is that in a highly stable environment, a plentiful source of energy and the ability to recycle their dead with almost no loss of energy, there is no environmental pressure to evolve, so the microbes have remained virtually unchanged for hundreds of millions, even billions of years.

Refuting Creationism - Tiny Shells Hold a Record of Sea Temperature Changes 10,000 Years Before 'Creation Week'

Earth's last ice age may provide crucial insights into the future behavior of El Niño events,

Foraminifera fossils

Ice age clues point to more extreme weather patterns in our future | University of Arizona News

With so much of Earth history occurring before creationism's little god allegedly created a small flat planet with a dome over it in the Middle East, it's useful to be able to recover data on global events such as climate change and sea temperature changes that can be projected into the future to predict what changes we can expect.

The 'El Niño' is a climate phenomenon that has a profound effect on world climate. It occurs every 2-7 years and is characterized by a warming of the sea surface in the central and eastern Pacific Ocean. It changes ocean currents, atmospheric humidity and rainfall, and jet streams that drive weather patterns, so understanding when these events occurred in the past and mapping them onto known climate patterns can help us predict future weather patterns.

Now scientist at the University of Arizona have developed a model for predicting how El Niño affects global weather patterns which needs to be validated against actual data, so they have analyzed the record of sea temperature change recorded in deposits of tiny foraminifera shells in ocean sediment, going back to the last Ice Age, 10,000 years before creationists think Earth existed.

Of course, the reason was not to refute creationism - it does that incidentally - but to provide a longer history on which to base future predictions than are currently available.

Refuting Creationism - An Improved Method For Analysing Ancient Microfossils To Discover How Life Evolved

Research News - Unveiling Ancient Life: New Method Sheds Light on Early Cellular and Metabolic Evolution | Tohoku University Global Site

One of the clutch of science publications which casually and unintentionally refute creationism to be published today, comes in the form of a paper by a team from the University of Tokyo, Tohoku University and Kochi University, Japan, which describes a new method for analysing ancient microfossils, and so discovering more about how key processes evolved in early cellular life.

The purpose of this is to discover not whether (that is never in doubt) but the precise details of how and when these key processes evolved.

Refuting Creationism - Meteor Strikes Show Earth is NOT Perfectly Designed for (Human) Life!

A surface geology map of the proposed Massive Australian Precambrian-Cambrian Impact Structure.

Credit: Daniel Connelly

A potential 370-mile-wide crater in Australia, known as MAPCIS, may reshape our understanding of Earth’s geological history. Researchers found geological evidence, including shocked minerals and melt rock, suggesting a massive impact at the end of the Ediacaran period. (Artist’s concept.)

Credit: SciTechDaily.com

Australian crater could offer fresh insight into Earth’s geological history - VCU News - Virginia Commonwealth University

It's a sign of their parochial ignorance that creationists believe their magic designer created Earth to be a perfect planet for them to live on. This notion fails to take into account the fact that, for many people, especially in the technologically under-developed parts of the world, life can be a struggle against disease, natural disasters, a lack of water and famine.

It also fails to take into account the record of natural disasters of a cosmological origin such as meteor strikes that have caused sudden mass extinctions in the vast length of time before creationists believe Earth was 'perfectly' created as a small flat planet with a dome over it in the Middle East.

Geologists from Virginia Commonwealth University (VCU), have identified the remnants of one such massive impact crater in the heart of Australia, measuring some 370 miles across. This impact is believed to have occurred toward the end of the Ediacaran period of Earth’s history, some 540 million years ago.

Refuting Creationism - How, Properly Understood, A Biblical Myth Probably Refutes Creationism.

A violent flood of the Kosi River in the Purniya district, Bihar, India.

Image: Shutterstock

Wylausing State Park in Southern Wisconsin where the Wisconsin River flows into the Mississippi.

Breakthrough study from IU scientists predicts catastrophic river shifts that threaten millions worldwide: College of Arts + Sciences : Indiana University

According to researchers from Indiana University, Jackson School of Geosciences, University of Texas at Austin and the University of Minnesota, rivers can and do frequently change their course in an event known as an avulsion. The initial stage of this process is often a catastrophic flood costing thousands of lives and billions of dollars.

The authors speculate that these events could be the origin of numerous flood myths throughout history, especially the history of people living in flood plains of major river systems such as the Tigris and Euphrates on which the Epic of Gilgamesh was based.

The Suncook River, New Hampshire, 2006

The Epic of Gilgamesh, which even in its original form was never more than a story about a local flood, is believed to be the source of the Hebrew origin myth of Noah's Ark.

Ironically, these catastrophic avulsion events, of which the Noah's Ark myth is probably a result, are reminders of just how hostile this planet can suddenly become, giving the lie to parochial creationists assertions that Earth is perfectly designed for life (especially their life). Sudden major river avulsions impact dramatically on people living peacefully in river valleys where soil fertility and water can create the impression of a nicely ordered and well-designed place for life to exist.

Refuting Creationism - Earth May Have had A Ring System 486 Million Years Before 'Creation Week'

An asteroid disintegrates under tidal forces as it approaches Earth

AI generated (ChatGPT4o)

Artist's impression.

Oliver Hull

Earth may have had a ring system 466 million years ago - Science

I know I'm always writing about things that happened before creationism's mythical 'Creation Week', but the problem is, almost everything that happened happened then. 99.9975% of Earth's history happened then, for example, and far more of the Universe's, since the Universe is some 3-4 times as old as Earth and an awful lot happened between the Big Bang and the formation of the sun and its planetary system.

And so, true to form, this is about the time 466 million years ago, when, according to the findings of three researchers from Monash University, Melbourne, Victoria, Australia, led by Professor Andrew G. Thomkins, Earth had a ring system, somewhat like those of Jupiter and Saturn. They believe the ring was composed of the debris of a large asteroid that passed close enough to Earth to be broken up by gravitational tidal forces.

The result was a sudden plunge into an ice age and a period of intense bombardment with meteorites lasting millions of years and producing an otherwise difficult to explain pattern of impact craters.

Refuting Creationism - Why Multicellular Life Evolved - Hundreds Of Millions Of Years Before 'Creation Week'

Cap carbonate rock, South China

Credit: Yarong Liu

Explaining dramatic planetwide changes after world’s last ‘Snowball Earth’ event | UW News

These panels show the new theory for the three phases that ended the Snowball Earth event. In the first stage, thick ice sheets separate most of the atmosphere and ocean. In the second stage, freshwater flows into the ocean to join meltwater floating on the ocean’s surface. In the final stage, ocean mixing resumes, allowing exchanges between the atmosphere, upper ocean and deep ocean.

Thomas, T.B & Catling D.C (2024).

A major theme of the creationist superstition is the childish notion that Earth was perfectly designed for life (and their life in particular because the designer created it all for them).

This of course, as with so much else in creationism, requires a genuine or contrived ignorance of the real world outside their small part of it, or they might notice that large parts of Earth are very hostile to most forms of life, especially multicellular life, and are inhabited, if at all, only by a few extremophile single-celled organisms such as bacteria, archaea and simple algae. Human life is impossible without special equipment at the poles, in deserts, at the top of higher mountains and in the oceans, for example. In fact, the proportion of Earth that is habitable by humans without clothing and shelter is very small indeed.

And there have been times in the past, in that long period of Earth's history that occurred before creationism's mythical 'Creation Week' in which a magic man made of nothing made everything else out of nothing, when Earth was uninhabitable by anything more complex than bacteria and archaea that could life in the depths of the oceans, because Earth was encased in a coating of ice up to 1 Km (0.6 miles) thick, in what is called 'snowball Earth' when the northern and southern icecaps extended until they met at the equator, making terrestrial life impossible.

Refuting Creationism - How Earth's Unstable Landmasses Keep Driving Evolution

The San Andreas Fault

Photograph: Georg Gerster

Rift Valley in Kenya, Africa, where plates are pulling apart.

Photo by Peter Prokosch

Witness 1.8 billion years of tectonic plates dance across Earth’s surface in a new animation

The basis for any evolutionary change is environmental change. Providing that change is slow enough for living organisms to adapt they will adapt and change as the environment changes. This is how life contrives to make Earth look as though it is fine-tuned for life when the reality is that life is fine-tuned for Earth and the tuning mechanism is evolution.

But ask any small-town, American Bible Belt creationist and they will assure you Earth was perfectly designed for life, especially life of the human variety. It's pretty much like small-town American Bible Belt country, all over!

In fact, throughout its history, 99.9975% of which occurred before creationists think Earth was created, Earth has been in a state of dynamic change which, as soon as life manages to get close to tuning itself to it, it’s changed again. The underlying cause of this is mostly plate tectonics which keeps on breaking landmasses apart, sending them scudding across the surface of the planet from the tropics to the poles and ramming them into one another again, creating uplift mountains, deep ocean trenches and volcanos which keep pumping out greenhouse gasses and changing the climate, sometimes quite suddenly.

To illustrate this, a team of geologists, led by Xianzhi Cao of Ocean University of China, and including Professor Allan S. Collins of The University of Adelaide, Australia have reconstructed the last 1.8 billion years of Earth's geography.

How they did it and what it tells us is the subject of an article by Professor Collins in The Conversation. His article is reprinted here under a Creative Commons licence, reformatted for stylistic consistency:

Fine-Tuned Fallacy Exposed - How Earth's Ecosystems Caused Multiple Mass Extinctions Between 185 And 85 Million Years Before 'Creation Week'

Fossils of Crinoids that were probably killed in an Oceanic Anoxic Event

Credit: Professor Tom Gernon

Land-sea tag-team devastated ocean life millions of years ago reveal scientists | University of Southampton

It can only be by remaining wilfully ignorant of the history of life on Earth and how it has been affected by catastrohic changes, that creationists are able to maintain the childish delusion that Earth is somehow fine-tuned for life, and especially their life.

The fact that very much of the surface of Earth, such as oceans, deserts and high mountain ranges is lethal without special equipment, and without cloths, shelter and fire , most of the northern and southern latitudes are not survivable in an average winter should be a clue to the fallacy of the claim, but then, from the safety of small town, Bible Belt America, where the rest of the world might as well not exist, such places can be safely ignored.

But the fact remains, whether ignored or not, that there have been several periods in the history of life on Earth that the planet has become a very hostile place, resulting in mass extinctions wheree life looked as though someone had hit the reset button. The primary cause of these fluctuations is almost certinly plate techtonics which, through mid-ocean ridge activity, release sulphates and phosphates which produce blooms of plankton which then die, locking up carbon and producing anoxic sediments on the ocean bed, and by releasing CO₂ into the atmosphere where if causes a rise in ocean temperature.

Volcanic activity also produces basalt which, when eroded and washed into the sea adds to the phosphates which produce planktonic blooms and subsequent deoxygenation.

How these terrestrial and marine sources act together to produce the frequent OAEs has now been explained.

Creationism Refuted - What a Mallorcan Cave Tells Us Of Events Before 'Creation Week'.

Bogdan Onac studies the phreatic overgrowths seen in this photo. They grow exactly at sea level and offer a more accurate reconstruction of past sea level history. He used these to determine the age of the submerged bridge.

Photo: M.À. Perelló

Close-up view of the submerged stone bridge from Genovesa Cave, Mallorca, Spain

Photo: R. Landreth

What a submerged ancient bridge discovered in a Spanish cave reveals about early human settlement

The Spanish Balearic Island of Mallorca (Majorca), a favourite holiday destination for Brits looking for sun, sea and sand, is composed largely of limestone which lends itself to cave formation and limestone caves lend themselves to stalactite formation.

They also provided shelters for early humans, so the evidence of human presence gives us a good picture of the timing of human migration into the area.

Like 99,9975% of Earth's history, the events recorded in these Mallorcan caves happened in the long pre-'Creation Week' history, long before creationists believe Earth was made out of nothing by magic.

Readers may recall my recent blog post concerning what is known of the changes in biodiversity as the Mediterranean dried up, then flooded again about 5.5 million years ago due to plate tectonic movements. These Mallorcan caves formed after those catastrophic events but still well before creationism's 'Creation Week'.

The stalactites in one cave in particular, the Genovesa Cave at the eastern end of the island hold a record of sea-level changes that correlate with known periods of glaciation and interglacial warmer periods. During periods of glaciation, water was locked up in polar ice and glaciers, so sea-levels fell.

What information do you have on the Genovesa Cave in Mallorca, Spain, and what it tells us of sea-level changes? Genovesa Cave, located on the eastern coast of Mallorca, Spain, is a notable site for studying past sea-level changes due to its unique speleothem formations (such as stalactites and stalagmites) and its position relative to current sea levels.

Key Information About Genovesa Cave

1. Geological Context:
   • Genovesa Cave is a partially submerged cave system found on the island of Mallorca, part of the Balearic Islands in the western Mediterranean Sea.
   • The cave has been naturally formed in limestone rock, a type of carbonate rock that is particularly responsive to changes in sea level.
   
   
2. Evidence of Past Sea-Level Changes:
   • Speleothem Growth Stages: The most significant evidence for past sea-level changes comes from speleothems, which are mineral deposits formed in caves by the precipitation of carbonate minerals from dripping water. When sea levels rise, the cave becomes submerged, and speleothem growth ceases due to a lack of contact with air. When sea levels fall, the cave is re-exposed to air, allowing speleothems to grow again.
   • Dating Techniques: Researchers use uranium-thorium (U-Th) dating methods to date these speleothems accurately. The growth and cessation periods can be correlated with known global sea-level fluctuations, such as those associated with glacial and interglacial cycles during the Quaternary period (the last 2.6 million years).
   
   
3. Sea-Level Highstands and Lowstands:
   
   
   • Studies of Genovesa Cave have identified speleothems that formed during several past interglacial periods when sea levels were higher than today. This provides evidence for higher sea levels during warm periods such as the Last Interglacial (about 125,000 years ago).
   • Conversely, periods when the cave was submerged or when speleothem growth was halted correspond to glacial periods when sea levels were much lower, sometimes up to 120 meters lower than the current level.

Implications for Understanding Sea-Level Changes

1. Local and Global Sea-Level Correlation:
   • The data obtained from Genovesa Cave speleothems align well with global records of sea-level changes, such as those derived from coral reefs and marine terraces. This reinforces the idea that the cave provides a reliable local record that reflects broader, global sea-level trends.
   
   
2. Understanding the Mediterranean Sea's Response:
   • The cave's findings contribute to our understanding of how the Mediterranean Sea responded to global climatic events. During periods of rapid deglaciation, for example, meltwater pulses could have caused rapid sea-level rises, which would be recorded in the cave's geological formations.
   
   
3. Insights into Future Sea-Level Rise:
   • Studying past sea levels helps scientists predict future changes, particularly in the context of global warming and potential ice sheet melting. The high-resolution records from Genovesa Cave can help refine models of future sea-level rise, especially in understanding how fast and how much sea levels could change.

In Summary

Genovesa Cave in Mallorca is a critical natural archive for studying past sea-level changes, providing both a local record of changes in the Mediterranean and contributing to the understanding of global sea-level fluctuations. The cave's speleothem formations, when dated, tell us about the timing and extent of past sea levels, helping us predict future changes.

Did the cave exist during the Messinian Salinity Crisis and the following Zanclean flood?

Genovesa Cave, like many other karstic cave systems on Mallorca, likely did not exist in its current form during the Messinian Salinity Crisis (MSC) and the subsequent Zanclean flood. However, understanding its formation requires a bit of geological context about these events and the development of the cave.

Geological Context of the Messinian Salinity Crisis and Zanclean Flood

1. Messinian Salinity Crisis (MSC) (5.96 to 5.33 million years ago):
   • The MSC was a period when the Mediterranean Sea was largely cut off from the Atlantic Ocean due to tectonic movements, leading to extreme evaporation and a significant drop in sea level. During this time, the Mediterranean became partially or fully desiccated, creating vast salt deposits and deep erosional features (like canyons and river systems) that extended below the current sea level.
   • Sea levels were drastically lower, estimated to have dropped by as much as 1,500 meters. The drop exposed large portions of the continental shelf and caused significant erosion of the landscape, including the areas around Mallorca.
   
   
2. Zanclean Flood (5.33 million years ago):
   • The Zanclean flood marked the end of the MSC, when the Strait of Gibraltar reopened, and Atlantic waters rapidly refilled the Mediterranean basin. This event is thought to have raised sea levels in the Mediterranean by up to 1,500 meters over a short period, flooding the previously exposed and desiccated areas.

Did Genovesa Cave Exist During These Events?

1. Formation of Genovesa Cave:
   • Genovesa Cave, like many karst caves, formed much later than the Messinian Salinity Crisis and the Zanclean flood. The formation of such caves typically occurs over long periods through the dissolution of limestone by slightly acidic groundwater. This process, known as karstification, is generally linked to periods when the sea level is relatively stable and when the water table is at an appropriate level to facilitate cave development.
   • Given that the MSC was a period of extreme environmental conditions (both in terms of erosion during the desiccation and rapid flooding during the Zanclean flood), the specific geological setting that would allow for the gradual formation of karstic caves like Genovesa likely did not exist until after these events.
   
   
2. Post-MSC Karst Development:
   • After the Mediterranean was refilled and the sea level stabilized following the Zanclean flood, conditions would have been more suitable for the formation of karst systems like Genovesa Cave. The Quaternary period, which began about 2.6 million years ago, saw multiple cycles of glacial and interglacial periods, during which fluctuations in sea levels, combined with periods of stability, promoted the development of karst caves in the limestone regions of Mallorca.
   
   
3. Timing of Cave Formation:
   • The specific timing of the formation of Genovesa Cave is not precisely known, but it is generally accepted that most of the karst caves in Mallorca formed during the Pleistocene epoch (2.6 million to 11,700 years ago) or even more recently. The cave's features and deposits suggest that it has undergone several phases of exposure and submersion due to sea-level changes throughout this period, well after the MSC and Zanclean flood.

Conclusion

Genovesa Cave, in its current form, did not exist during the Messinian Salinity Crisis or the subsequent Zanclean flood. The cave likely formed much later, during the Quaternary period, as conditions became suitable for karstification following the stabilization of Mediterranean sea levels after these dramatic geological events. The MSC and the Zanclean flood were important in shaping the broader landscape of the Mediterranean region, but the specific conditions necessary for the formation of caves like Genovesa developed much later.

What are phreatic overgrowths on Speleothems (POS)?

Phreatic overgrowths on speleothems (POS) are unique mineral deposits that form in coastal cave environments at the interface between freshwater and seawater. These overgrowths are specifically associated with periods when the cave is partially submerged in a mix of fresh and saline water, typically at or near sea level. They provide important clues about past sea-level positions and climate conditions.

Key Characteristics of Phreatic Overgrowths on Speleothems

1. Definition:
   • Phreatic overgrowths on speleothems are secondary carbonate deposits, typically composed of minerals like calcite or aragonite. They form on existing speleothems (such as stalactites, stalagmites, or flowstones) when the cave environment is inundated by a fluctuating water table that is influenced by sea level.
2. Formation Environment:
   • These overgrowths develop in the "phreatic zone" of caves— the zone that is below the water table and is saturated with water. In coastal caves, this zone is directly affected by sea-level changes. When sea level is stable or fluctuates within a certain range, the mixing zone between freshwater and saline water can lead to mineral precipitation on submerged speleothems.
3. Mechanism of Formation:
   • Phreatic overgrowths form due to a process known as "degassing" or "precipitation" when carbon dioxide (CO₂) dissolved in water escapes into the cave air. This loss of CO₂ from water that is saturated with calcium carbonate (CaCO₃) promotes the deposition of calcite or aragonite on existing cave formations.
   • In coastal caves, the mixing of fresh and saltwater enhances this process. Freshwater entering the cave mixes with seawater, creating conditions where minerals precipitate more readily due to changes in water chemistry, such as shifts in pH, temperature, and CO₂ concentration.
4. Morphology and Appearance:
   • Phreatic overgrowths typically form flat or gently sloping horizontal crusts, rims, or coatings on existing cave formations. Their horizontal nature reflects the stable water table level at which they formed.
   • These deposits can vary in thickness and are often found at multiple levels within the cave, corresponding to different sea levels over time.

Importance of Phreatic Overgrowths on Speleothems

1. Indicators of Past Sea Levels:
   • POS are valuable indicators of past sea levels because they form at specific elevations related to the water table, which in coastal environments is closely linked to sea level. By dating these formations using techniques such as uranium-thorium (U-Th) dating, scientists can reconstruct past sea-level positions and determine the timing and magnitude of sea-level changes over thousands to hundreds of thousands of years.
2. Understanding Paleoclimatic Conditions:
   • Beyond sea levels, POS can provide insights into broader paleoclimatic conditions. The chemical composition of these overgrowths (e.g., stable isotopes of oxygen and carbon) can offer information about past temperature, rainfall patterns, and even water source characteristics.
3. Calibrating Sea-Level Rise Models:
   • The precise dating of phreatic overgrowths helps in calibrating models of sea-level rise, particularly when cross-referenced with other geological and paleoclimatic data, such as coral reefs, marine terraces, and ice cores. This is particularly important for understanding the rate of sea-level rise in response to past climate events, such as glacial and interglacial periods.

Examples of POS Studies

• Mediterranean Caves (Mallorca, Spain): In Mallorca, POS have been extensively studied in caves like Genovesa Cave and others along the coast. These formations have been used to map out the history of Mediterranean sea-level changes over the last several hundred thousand years, including periods such as the Last Interglacial (about 125,000 years ago).
• Caribbean and Other Coastal Regions: Similar studies have been conducted in coastal caves in the Caribbean and other regions, where POS help reconstruct sea-level fluctuations and regional climate changes.

Summary

Phreatic overgrowths on speleothems are carbonate deposits formed in caves at the interface between freshwater and seawater, directly reflecting past sea levels. They serve as crucial archives for understanding past sea-level changes, climate conditions, and the complex interplay between global climate and regional environmental changes.

In the context of dating caves, what does the following mean?

'A ²³²Th/²³⁸U-²³⁴U/²³⁸U-²³⁰Th/²³⁸U (plotted as a Rosholt A type) isochron age of 5479 ± 120 years B.P.'

The phrase describes the result of a specific type of uranium-thorium dating method used to determine the age of materials, such as carbonate deposits in caves. Let's break down what each part of this phrase means:

Uranium-Thorium (U-Th) Dating Overview

Uranium-Thorium (U-Th) dating also known as Thorium-230 dating is a radiometric dating technique used to determine the age of calcium carbonate materials like speleothems (stalactites, stalagmites, and other cave formations). The method relies on the radioactive decay of uranium isotopes to thorium isotopes. Here's a breakdown of the isotopes involved:

• ²³⁸U (Uranium-238): The parent isotope, which decays over time into various intermediate daughter isotopes, including ²³⁴U (Uranium-234) and ²³⁰Th (Thorium-230).
• ²³²Th (Thorium-232): A stable, non-radioactive isotope of thorium that is not involved in the decay chain but can be present in the sample as a contaminant or from initial conditions.

Explanation of the Phrase

1. "²³²Th/²³⁸U-²³⁴U/²³⁸U-²³⁰Th/²³⁸U":
   • These ratios represent the proportions of different isotopes present in the sample.
     • ²³²Th/²³⁸U: Indicates the ratio of thorium-232 to uranium-238 in the sample.
     • ²³⁴U/²³⁸U: Indicates the ratio of uranium-234 (an intermediate decay product) to uranium-238.
     • ²³⁰Th/²³⁸U: Indicates the ratio of thorium-230 (the target daughter isotope) to uranium-238.
   
   
2. "Plotted as a Rosholt A type isochron":
   • An isochron is a graphical method used to determine the age of a sample by plotting the ratios of isotopes against each other. The slope of the line (the isochron) represents the time that has passed since the sample's formation.
   • "Rosholt A type" refers to a specific type of isochron plot developed by John Rosholt, which plots the ratios of these isotopes in a way that accounts for initial thorium contamination (²³²Th). This method provides a more accurate age by correcting for the presence of any initial, non-radiogenic thorium in the sample.
   
   
3. "Isochron age of 5479 ± 120 years B.P.":
   • This is the calculated age of the sample, determined by the U-Th dating method using the isochron plot.
   • 5479 years B.P.: This means "5479 years Before Present," where "Before Present" is typically defined as before the year 1950. The sample is estimated to have formed 5479 years ago.
   • ± 120 years: This represents the margin of error or uncertainty in the dating. The true age is likely within the range of 5479 years plus or minus 120 years (i.e., between 5359 and 5599 years ago).

Summary

The phrase refers to a method of dating a cave sample using uranium-thorium dating and an isochron plot (Rosholt A type) to determine that the sample is approximately 5479 years old, with an uncertainty of ±120 years. The use of multiple isotope ratios and the isochron method helps correct for initial contamination and provides a more accurate age estimate.

This allowed stalactites to grow as water containing dissolved minerals seeped through the cave roof and dripped down, evaporating as it did so, and leaving a record of rainfall. During interglacial period, sea-levels rose, submerging the caves and preventing the growth of stalactites, leaving a record of these sea-level rises.

But, apart from these records of climate and sea-level changes, the Genovesa Cave contains a more tangible record - that of human habitation on the island and so of colonisation of the Western Mediterranean and the Iberian peninsula in particular.

It is a submerged stone bridge, built when the sea-levels were lower at the height of the last ice age. The bridge was used to cross a now submerged small lake at a low point in the cave system and must have been deliberately constructed.

Scientists these days rarely, if ever, set out to refute creationist mythology but all do so incidentally, simply by doing what good science does and discovering the facts, and this discovery, by speleogeologists from the University of South Florida, does just that. It is the subject of a recent open access paper in Communications Earth & Environment and a recent news release from the University of South Florida:

What a submerged ancient bridge discovered in a Spanish cave reveals about early human settlement

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A new study led by the University of South Florida has shed light on the human colonization of the western Mediterranean, revealing that humans settled there much earlier than previously believed. This research, detailed in a recent issue of the journal, Communications Earth & Environment, challenges long-held assumptions and narrows the gap between the settlement timelines of islands throughout the Mediterranean region.

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Reconstructing early human colonization on Mediterranean islands is challenging due to limited archaeological evidence. By studying a 25-foot submerged bridge, an interdisciplinary research team – led by USF geology Professor Bogdan Onac – was able to provide compelling evidence of earlier human activity inside Genovesa Cave, located in the Spanish island of Mallorca.

The presence of this submerged bridge and other artifacts indicates a sophisticated level of activity, implying that early settlers recognized the cave's water resources and strategically built infrastructure to navigate it.

Professor Bogdan P. Onac, Lead author
Karst Research Group
School of Geosciences
University of South Florida, Tampa, FL, USA.

The cave, located near Mallorca’s coast, has passages now flooded due to rising sea levels, with distinct calcite encrustations forming during periods of high sea level. These formations, along with a light-colored band on the submerged bridge, serve as proxies for precisely tracking historical sea-level changes and dating the bridge's construction.

Mallorca, despite being the sixth largest island in the Mediterranean, was among the last to be colonized. Previous research suggested human presence as far back as 9,000 years, but inconsistencies and poor preservation of the radiocarbon dated material, such as nearby bones and pottery, led to doubts about these findings. Newer studies have used charcoal, ash and bones found on the island to create a timeline of human settlement about 4,400 years ago. This aligns the timeline of human presence with significant environmental events, such as the extinction of the goat-antelope genus Myotragus balearicus.

By analyzing overgrowths of minerals on the bridge and the elevation of a coloration band on the bridge, Onac and the team discovered the bridge was constructed nearly 6,000 years ago, more than two-thousand years older than the previous estimation – narrowing the timeline gap between eastern and western Mediterranean settlements.

This research underscores the importance of interdisciplinary collaboration in uncovering historical truths and advancing our understanding of human history.

Professor Bogdan P. Onac.

This study was supported by several National Science Foundation grants and involved extensive fieldwork, including underwater exploration and precise dating techniques. Onac will continue exploring cave systems, some of which have deposits that formed millions of years ago, so he can identify preindustrial sea levels and examine the impact of modern greenhouse warming on sea-level rise.

This research was done in collaboration with Harvard University, the University of New Mexico and the University of Balearic Islands.

Abstract
Reconstructing early human colonization of the Balearic Islands in the western Mediterranean is challenging due to limited archaeological evidence. Current understanding places human arrival ~4400 years ago. Here, U-series data from phreatic overgrowth on speleothems are combined with the discovery of a submerged bridge in Genovesa Cave that exhibits a distinctive coloration band near its top. The band is at the same depth as the phreatic overgrowth on speleothems (−1.1 meters), both of which indicate a sea-level stillstand between ~6000 and ~5400 years ago. Integrating the bridge depth with a high-resolution Holocene sea-level curve for Mallorca and the dated phreatic overgrowth on speleothems level constrains the construction of the bridge between ~6000 and ~5600 years ago. Subsequent sea-level rise flooded the archeological structure, ruling out later construction dates. This provides evidence for early human presence on the island dating at least 5600 and possibly beyond ~6000 years ago.

Introduction
Mallorca, the main island of the Balearic Archipelago, is the sixth largest in the Mediterranean Sea, yet it was among the last to be colonized¹. An in-depth discussion concerning the earliest colonization of various Mediterranean islands, including Mallorca, may be found in Cherry and Leppard1, Dawson², and Simmons³. Despite extensive research on this topic, there has been considerable disagreement about the timing of the earliest colonization of Mallorca. Radiocarbon dating of bone material excavated from Cova (Cave) de Moleta indicate human presence on the island as early as 7000 calibrated years before present (cal B.P.)⁴. Subsequent age determinations from findings in Cova de Canet, further extended the timeline, suggesting human occupation dating back to approximately 9000 cal B.P.⁵. A series of publications^{6,7,8,9,10,11} revealed inconsistencies regarding the exact stratigraphic position and context of the dated bone (sample KBN-640d12) in Cova de Moleta. Due to the overall poor preservation of the samples and the lack of clear and specific information on this particular radiocarbon-dated sample, Ramis and Alcover⁷ suggested that the bone fragment, initially identified as human, might actually belong to M. balearicus, an endemic bovid. Consequently, this sample was considered not relevant for determining the timing of the island’s colonization. Similarly, the radiocarbon dates from Cova de Canet were considered highly controversial because they originate from a charcoal layer that lacks clear evidence of human activity^7,8. Furthermore, in neither of these caves do the M. balearicus bones show butchery marks, making it difficult to establish a clear link to contemporary human presence2. Due to the aforementioned issues these early results were deemed unreliable^1,8,13.

Several studies have reevaluated most of the previously dated materials and supplemented them with new radiocarbon dates obtained from charcoal, ash, and bones^6,7,9,10. Based on these new results, there is now a consensus that the timeframe for earliest human settlement on the island is between 4600 and 4200 cal B.P.¹⁴.

Dawson2 presents a synthesis of the various lines of argument regarding arrival models in the Balearic islands that includes: (1) Early (~9000 cal B.P.), (2) Intermediate (~7600 cal B.P.), and (3) Late (~5000 cal B.P.) arrival phases. The last two models suggest the existence of stable settlements, yet only the third one has been deemed plausible in the local archeological literature^7,8,14.

While there has been a growing body of evidence revealing progressively earlier human settlements on many islands in the Mediterranean basin, the timeline for the initial human colonization in Mallorca has seen relatively minor adjustments over the past decades^8,15,16. The latest research suggests that this colonization occurred approximately 4400 cal B.P., coinciding with the human-mediated extinction of Myotragus balearicus¹⁴. This conclusion is based on two radiocarbon ages, which provide a relatively narrow time window of 350 years (p > 90%) between the last documented Myotragus bone (4581–4417 cal B.P.) and the first dated sheep bone (4417–4231 cal B.P.). However, it remains challenging to confirm whether the ages of these paleontological remains represent the latest or the earliest such occurrences on the island. Subsequent field work may shed light on this matter.

Our study site is a submerged archeological structure in the Genovesa Cave (also known as Cova de’n Bessó; 39°31’32” N, 3°19’2” E), situated in the eastern part of Mallorca (Fig. 1a, b). The cave hosts ceramic sherds and stone constructions. The latter includes a stone-paved path that connects the cave entrance to the first underground lake (Fig. 1d), a cyclopean stone wall running parallel to the path, and an 8.62 m long¹⁷ and 0.5 m high stone walkway (hereafter referred as to bridge) oriented NE–SW (Fig. 1c, e, Supplementary Fig. 1, Supplementary Table 1). This last structure was built across a lake by stacking large limestone breakdown blocks on top of each other, without the use of mortar or cement. The uppermost layer comprises flat boulders of considerable size (Supplementary Fig. 1b). The largest stone measures 1.63 m in length and 0.6 m in width. Relative to the preindustrial (pre-1900 CE) sea level, the bridge is submerged by 1.05 ± 0.1 m of water at its upper part (Figs. 1e, 2). However, at the time of its construction, it served as an access path to the only other dry chamber in the cave (Sala de les Rates-pinyades, i.e., Bats Room), where pottery, tentatively attributed to the Naviform period (ca. 3550–3000 cal B.P.) was discovered^18,19. The bridge structure was inferred to have been built around the same period²⁰.

Fig. 1: Cave and sample locations.

a Map showing Mallorca in the western Mediterranean (black square). b Location of Genovesa and Drac caves; CCG: Closos de Can Gaià archeological site. c Plan of Genovesa Cave showing the location of the phreatic overgrowth on speleothems samples (yellow circles) and the survey station (red dot). d Photograph of the stone-paved path leading to the bridge (person height = 167 cm). e Cross-section (x–x’) indicating the location of the submerged bridge relative to the cave entrance and the present sea level. Maps (a, b) are available under CC Public Domain License from https://pixabay.com/illustrations/map-europe-world-earth-continent-2672639/ and https://pixabay.com/illustrations/mallorca-map-land-country-europe-968363/, respectively.

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Fig. 2: Positional relationship between the bridge, preindustrial sea level, and analyzed samples.

The cross sections depict the spatial relationship between the submerged bridge and the U-series dated samples (phreatic overgrowth on speleothems: orange/yellow spindle; soda straw tips: red circle) from Genovesa and Drac caves. The vertical scale applies uniformly to all samples from both caves. All ages are reported as thousands of years (kyr) before present, where present is defined as 1950 CE.

Here, we integrate uranium-series (U-series) age data acquired from phreatic overgrowth on speleothems and stalactite tips in Genovesa and Drac caves, along with Late Holocene relative sea level (RSL) information available for Mallorca²¹. Additionally, we consider the presence of the bridge, the coloration mark on its upper part, and the depths at which these respective features occur. This combined evidence contributes valuable insights to the ongoing debate surrounding the timing of human colonization on Mallorca.

Because Creationists love to find fault with the geochronology in these records of pre-'Creation Week' events, I've included sections on geochronology here:

Results and discussion
Speleothems and sea level
Proxies for cave-based sea-level reconstructions include mineralogical (sediments, speleothems)^22,23, archeological (fish tanks, saltpans, submerged structures, etc.)²⁴, and biological (borings, worm tubes, etc.)²⁴ records. In the case of Genovesa Cave, a typical coastal karst feature situated <450 m from the shoreline, both mineralogical and archeological records are present. Many of its well-decorated passages, galleries, and chambers are now flooded due to rising sea levels²⁰. Because of the cave’s proximity to the coast and the high permeability of the Upper Miocene host rock²⁵, the hydraulic gradient is negligible (9 × 10^-5 m /m) for such short distances (see Methods), and thus the water table in the cave is, and was in the past, coincident with sea ^26,27. During times of high sea level stillstands, when the cave was partly flooded, distinct encrustations of calcite and aragonite accumulated over preexisting stalactites, forming the so-called phreatic overgrowths on speleothems²⁸ (POS). This is a particularly useful proxy for precisely and accurately reconstructing sea-level changes across various timescales^21,29. Furthermore, ordinary stalactites, which form in cave passages above the water table and later become submerged as sea-levels rise are also valuable in this process since they document the moment when the cave shifted from being air- to water-filled²².

A distinct light-colored band (~15 cm wide) is visible along the entire bridge at its upper part (Fig. 2, Supplementary Fig. 1a). This coloration mark bears a resemblance to a “bathtub ring” and its presence is likely related to a relatively short-lived stable water table that allowed the precipitation of a sub-millimeter calcite crust at the water/air interface. When the water level increased, the calcite did not disappear since the water below the water table remained somewhat saturated with respect to calcium carbonate. As discussed later, this feature along with the new POS ages and their elevation play a crucial role in determining when this bridge, now submerged, was constructed.

Geochronology
The U-series ages (n = 34; 28 for POS and 6 from stalactites) are given in Supplementary Table 2 and are all reported as years before present (BP), where present is 1950 CE. Ten of these ages are from POS samples GE-D8 (Genovesa Cave; Supplementary Fig. 2) and DR-D15 dated as part of a prior study²¹. The latter was collected in Drac Cave (39°32’9” N, 3°19’49” E), located 1.6 km to the north-east of Genovesa Cave (Fig. 1c, Supplementary Figs. S3–S4).

Regardless of the sampling depth, all the vadose stalactites on which the POS formed in both caves, produced ages older than 8200 years B.P. (Fig. 2, Supplementary Fig. 5). The phreatic overgrowth samples GE-D6, GE-D7, and DR-D23 (Supplementary Figs. S6–S8), precipitated at ~1.10 ± 0.1 m below the preindustrial sea level (mbpsl). A ²³²Th/²³⁸U-²³⁴U/²³⁸U-²³⁰Th/²³⁸U (plotted as a Rosholt A type) isochron age of 5479 ± 120 years B.P. (n = 3 of 4; hereafter, ± refers to 2 σ uncertainty) was measured for GE-D6 (Supplemental Table 2, Supplementary Fig. 9a). GE-D7, in the same room and at the same elevation as GE-D6, yielded a weighted average age of 5510 ± 549 years B.P. using the same correction (initial ²³⁰Th/²³²Th atomic ratio = 5.1 ± 0.4 ppm) generated by the GE-D6 isochron age. Onac et al.²¹. used a slightly higher initial for GE-D8 (8 ppm) that was located at a higher elevation than GE-D6 & -D7. For DR-D23, we obtained a ²³²Th/²³⁸U-²³⁴U/²³⁸U-²³⁰Th/²³⁸U (plotted as a Rosholt A type) isochron age of 5824 ± 140 years B.P. (n = 6) (Supplementary Table 2, Supplementary Fig. 9b). This isochron shows an exceptionally high initial ²³⁰Th/²³²Th atomic ratio = 527.5 ± 22.1 ppm, more than 10x higher than used for DR-D15 (44 ppm) from the same cave but at a different elevation²¹. The fluffy fibrous cotton-candy texture of the two sub-samples with high U component of DR-D23 may have something to do with the high initial ²³⁰Th/²³²Th. The isochron ages were necessary to produce accurate ages with smaller uncertainties.

Collectively, the POS data from Genovesa and the nearby Drac, reveal three distinct periods of relative sea-level stability (Fig. 2). One occurred at 0 ± 0.04 m from 2720 ± 11 to 296 ± 18 years B.P. The second period lasting from 3703 ± 14 to 3368 ± 8 years B.P., corresponds to a sea level of 0.25 mbpsl. Lastly, a third period at ~1.1 ± 0.1 mbpsl is documented between 5820 ± 140 and 5479 ± 120 years B.P. (Figs. 2, 3). By adding the uncertainty to the older age and subtracting the uncertainty from the younger age, the maximum time span of POS growth at 1.1 mbpsl ranges from 5964 – 5359 years B.P. During this interval, both the POS and the coloration mark formed. For the latter to develop, the bridge must have been submerged, at least to its upper surface, allowing calcite to precipitate during the sea-level stillstand. Therefore, this period is of particular interest because it may aid in providing the timeline of the bridge construction as detailed below.

Timing of bridge construction
The assembly date of the bridge in Genovesa Cave remains uncertain due to the absence of written records or a robust time-stratigraphic context. In order to constrain the building time of this archeological structure, we rely on a well-defined Late Holocene sea-level curve generated by Onac et al.²¹. for Mallorca (depicted by the solid blue line in Fig. 3) and the ages and depths at which POS grew and coloration mark formed. First, we assess previous assumptions regarding the timing of the submerged bridge construction using this curve. Then, we examine our new sea-level data in conjunction with the timing of the earliest human arrival model proposed by Bover et al.¹⁴.

The prehistoric pottery discovered in Sala de les Rates-pinyades of the Genovesa Cave has been linked to the Naviform period (3550–3000 cal B.P.). This attribution is based on typological similarities between the ceramics found in Genovesa and those documented at the Closos de Can Gaià, a Bronze Age site located ~10 km south of our cave (Fig. 1b). The archeological horizon in which comparable pottery was discovered at the latter site was dated to ~3600 cal B.P30. However, Costa and Guerrero31 argue that Closos de Can Gaià excavation required a reassessment of the chronological framework, due to issues with the radiocarbon dates. Despite this, adopting the previously reported radiocarbon age, Gràcia et al.²⁰ suggested that the construction of the bridge likely occurred toward the end of the Naviform period.

However, the RSL curve (Fig. 3) indicates that sea level was ~0.25 ± 0.1 m below the preindustrial baseline ~3500 years ago²¹, implying a total water depth of ~1.3 m in the cave lake. The vertical height of the bridge is 0.5 m, and thus it was submerged by 0.8 m of water at this time (Fig. 3). The construction of the bridge around 4400 years ago, the time suggested by Bover et al.¹⁴ to be the earliest evidence of human presence on the island, is also improbable. At that time, relative sea level in Mallorca was ~0.35 ± 0.1 m below preindustrial level, and the bridge would have been submerged by 0.7 m. Building a bridge below water level is a highly unlikely scenario, and thus it was likely built at an earlier time, when sea level was lower. The predicted relative sea-level curve for Mallorca (Fig. 3) indicates that the top of the bridge would have been close to water level no earlier than 5600 years ago and this provides an approximate lower bound on the age of the feature. The distinct coloration mark on the bridge also provides strong evidence of an age greater than the ages estimated by Gràcia et al.²⁰ and Bover et al.¹⁴. As discussed earlier and according to the POS-based relative sea-level record, this mark would not have developed if the top of the bridge was well below the water level, i.e., at times more recent than ~5500 years ago. However, an age older than 6000 years for the feature can be ruled out since sea level was even lower (Fig. 3), and the construction of a bridge at its current height would have been unnecessary.

Fig. 3: Proposed timing for bridge construction.

Comparison between the position of the submerged bridge, phreatic overgrowth on speleothems (POS), coloration mark, and the RSL prediction (blue curve)²¹ based on a Glacial Isostatic Adjustment model that uses the ICE-6G (VM 5) ice history with an upper mantle viscosity of 1.3 × 1020 Pa s. Solid symbols with age and depth uncertainties represent POS elevations. The brown rectangle depicts the bridge with its coloration band in the upper part. The insets show an underwater image of the bridge (Photo courtesy of R. Landreth) and a close-up view on the RSL position of samples GE-D6, GE-D7, and DR-D23 that grew at 1.1 mbpsl. The uncertainties for GE-D6, GE-D7, and DR-D23 are absolute 2 σ error bars based on three dimensional isochron ages or weighted average (GE-D7). The dotted blue line is a sea-level rise scenario that includes the brief stillstand inferred from the POS growth.

The phreatic overgrowths GE-D6, GE-D7, and DR-D23 from Genovesa and Drac caves formed at a relative sea level of 1.1 mbpsl, which is 5 cm below the upper part of the bridge. The two more precise isochron ages suggest sea-level remained relatively constant for a few hundreds of years between ~5964 and 5359 years B.P. The relative brevity of this time frame might explain why the morphology and size of the POS are somehow atypical and smaller compared to those POS that developed when the sea level was stable at 0 m for over 2000 years. Furthermore, this <600 year period of nearly constant sea level was sufficient to develop the coloration mark. Given that the occurrence of this feature correlates directly with the previously mentioned sea-level stillstand position, it suggests that the bridge was already in place. In fact, its construction could have commenced as early as ~6000 years ago when the water depth in the lake was ~0.25 m. However, it had to be completed before ~5600 years ago when the sea-level rose to the top surface of the bridge.

Onac, B.P., Polyak, V.J., Mitrovica, J.X. et al.
Submerged bridge constructed at least 5600 years ago indicates early human arrival in Mallorca, Spain. Commun Earth Environ 5, 457 (2024). https://doi.org/10.1038/s43247-024-01584-4

Copyright: © 2024 The authors.
Published by Springer Nature Ltd. Open access.
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)

Lots of stuff for creationists to lie about there. Firstly, there is the record of sea-level changes reflecting the advance and retreat of ice sheets over the past few tens of thousands of years.

Then there is the record of human habitation and construction of the bridge when creationist mythology says the world was subject to a genocidal flood in which all life was extinguished save a small handful of survivors that then repopulated the planet in just a few thousand years.

What a creationist now needs to do is explain why all the dating methods, which converge on these dates, are all wrong and should be converging on a much more recent date compatible with creation of Earth from nothing just 10,000 years ago and all human life originating from 8 related individuals just 4,000 years ago.

Sadly, because the authors of these myths knew nothing of the real history of the Western Mediterranean, the book they wrote, and which creationists think is a real history book, is entirely silent on the matter.