Earth Is Missing A Huge Layer Of Its Crust

Posted: Jan 5 2019, 10:15pm CST | by , Updated: Jan 5 2019, 10:24pm CST, in Latest Science News

 

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Earth is Missing a Huge Layer of its Crust
Credit: University of New Mexico

Researchers suggest that the missing crust layer can be blamed on 'Snowball Earth.'

In 1869, explorer and geologist John Wesley Powell noticed a huge amount of crust is missing from the Grand Canyon surface. The strange feature is especially evident in the flat-lying layered sedimentary rocks below the rims within Grand Canyon. Samples also showed that these rocks have a layer dating back 540 million years. Directly below it, we have a layer that formed around 1 billion years ago. This huge time gap in the rock record has been named "the Great Unconformity." This discrepancy has been observed on many places on Earth as well and has baffled researchers.

To explain the gap, researchers have also developed two theories. One theory suggests that a dramatic increase in sedimentation caused the Great Unconformity between ancient rocks and younger sediments. Another possibility is a large and rapid erosion event. That erosion event may have been triggered by "Snowball Earth" – a period when the entire planet was covered in ice. New study claims to have found evidence that supports the latter theory.

Scientists believe that the melting ice took a whole layer of the crust with it and dumped it into the sea. If that was the case, the seafloor should show a large layer of rock from that time period. Surprisingly, the putative layer has never been found. This is because the layer was pulled into the Earth's interior by the movement of the tectonic plates.

The scientists' conclusion arose out of crystals from the period in question. They had isotopes of hafnium and oxygen consistent with zircon crystals that have undergone erosion under cold conditions.

“We provide evidence that this unconformity may record rapid erosion during Neoproterozoic “snowball Earth” glaciations,” Authors wrote in the study. “We show that the extent of Phanerozoic sedimentation in shallow continental seas can be accurately reproduced by modeling the accommodation space produced by the proposed glacial erosion, underlining the importance of glaciation as a means for lowering erosional base level.”

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<a href="/latest_stories/all/all/47" rel="author">Hira Bashir</a>
The latest discoveries in science are the passion of Hira Bashir (). With years of experience, she is able to spot the most interesting new achievements of scientists around the world and cover them in easy to understand reporting.

 

 

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