Month: September 2022

ISOTOPE SUPPORT. “Support for this idea can also be found in the ratio of strontium isotopes. Strontium-87 mainly makes it into the ocean through the breakdown of continental rocks, whereas strontium-86 comes from mid-ocean ridges. The high point for strontium-87 over the past 900 million years occurred during the Cambrian, suggesting weathering peaked around then. The ratio of neodymium-143 to neodymium-144 (also known as εNd) also helps out by indicating the age of those continental rocks being weathered. Around the time that strontium-87 peaked, εNd hit a low point as continental weathering cut into older and older rocks.’ https://lnkd.in/dtYSB5v View in LinkedIn

CALCIFICATION CAMP. “That puts the relationship between the Great Unconformity and the Cambrian explosion in a much different light. The Great Unconformity may not simply be a gap in the record of early evolution of multicellular life with fossilizable hard parts. Instead, the seawater changes caused by the erosion that created the Great Unconformity may have driven the rise of biological calcification.” https://lnkd.in/dtYSB5v View in LinkedIn

CYCLIC TECTONICS. “The "great" unconformities of regional or continental scale (in both geography and chronology) are associated with either global changes in eustatic sea level or the supercontinent cycle, the periodic merger of all the continents into one approximately every 500 million years.” https://lnkd.in/ddDSSXe View in LinkedIn

GRAND CANYON UNCONFORMITY. “Within the Grand Canyon, the Great Unconformity represents a period of about 175 million years between the Tonto Group and the youngest subdivision, the Sixtymile Formation, of the Grand Canyon Supergroup. At the base of the Grand Canyon Supergroup, where it truncates the Bass Formation, the period of time represented by this angular unconformity increases to about 725 million years. Where the Tonto Group overlies the Vishnu Basement Rocks, the Great Unconformity represents a period as much as 1.2 to 1.6 billion years of time.” https://lnkd.in/ddDSSXe View in LinkedIn

UNKNOWNS. ‘The Great Unconformity (GU), a global erosion surface separating Precambrian and Paleozoic rocks, represents ∼100–1000 m.y. of missing geologic time. The timing of erosion and amount of denudation leading to the formation of the GU remains largely unknown, but could provide important constraints to models of cratonic vertical movements during the supercontinent cycle, and estimates of sediment production that influenced Neoproterozoic ocean-atmosphere chemistry.” https://lnkd.in/dDNSQTU View in LinkedIn

SNOWBALL EARTH THEORY. “It has long been observed that the sequence of sedimentary rocks deposited in the past half-billion years often sharply overlies older igneous or metamorphic basement at an erosional surface known as the Great Unconformity. We provide evidence that this unconformity may record rapid erosion during Neoproterozoic “snowball Earth” glaciations.” https://lnkd.in/d6fatHN View in LinkedIn

QUESTIONS. Was the Cambrian Explosion just an optical illusion caused by the Great Unconformity erasing a billion years of fossil history from the Earth? Was the Great Unconformity the result of millions of years of glacial scouring of the Earth’s surface, or the result of epic floods caused by the glaciers melting, or perhaps a combination of both? Was it relatively rapid (flooding) or slow (glaciation). View in LinkedIn

SO ENDS this first weekend on the Great Unconformity, surely one of the most disruptive events in our planet along with the birth of the moon, the meteorite phase, plate tectonics, the Great Oxygenation event, snowball earth, and multicellularity. This has suffered from relative obscurity: even a BBC summary of the 25 biggest turning points in Earth’s history fails to mention it. Somehow it got subducted in obscure and badly written geological articles. I have the sense that most people have never heard of this, including biologists who have twisted themselves into pretzels to explain the Cambrian Explosion. https://lnkd.in/dZRSWah View in LinkedIn

EPOCH 5. "According to Kurzweil, we are entering Epoch 5 with an accelerating rate of change. The major event of this merger of technology and human intelligence will be the emergence of a “technological singularity”." https://lnkd.in/dTveM5M View in LinkedIn

NON-BIOLOGICAL INTELLIGENCE. "Kurzweil believes that within a quarter century, non-biological intelligence will match the range and subtlety of human intelligence. It will then soar past it because of the continuing acceleration of information-based technologies, as well as the ability of machines to instantly share their knowledge." https://lnkd.in/dTveM5M View in LinkedIn