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Here's where the 200 million cubic mile chunk of rock from the Earth's crust has vanished

The massive chunk of rocks missing is said to have been eroded and washed into the ocean filling it with minerals that changed life on Earth.

BY THE DAILYNET STAFF

PUBLISHED JUL 28, 2024

Cover Image Source: Grand Canyon | Great Unconformity | Wiki Commons

Scientists have long tried to understand all about the "Great Unconformity" ever since it was coined by geologist Clarence Dutton back in 1880 after he was spellbound by the rocks at the Grand Canyon. You see, the Grand Canyon which is made up of rock layers, each representing a different time-period in the history of the Earth. He understood that the ones towards the bottom were created way before the rocks that were on the top.

He soon realized how there was a massive difference between the time periods when these two layers of rocks were formed, and this means that there is no record of those years in Earth's history. Today, we know that the rocks on top of the "Great Unconformity" were laid during the Cambrian Period which was about 500 million years ago, while the rocks below it were as old as 1.2 million years, pointing out a huge gap.

Grand Canyon Village, Arizona | Josh Brasted | Getty Images

This missing portion of the Earth's crust had baffled scientists for a while until new evidence revealed that their disappearance could be due to severe glacial erosions that occurred during a time known as “Snowball Earth,” when almost the entire planet was covered with ice.

This resulted in a gap in the sedimentary record and according to one study, a global average of 3-5 kilometres (2-3 miles) of rock was stripped away due to glacial erosion leaving them “missing” from the records.

A tourist assumes a risky position for a photo on the South Rim of Grand Canyon National Park | Paul Harris | Getty Images

The study led by Dr Brenhin Keller of the Berkeley Geochronology Center explains how the scale of the rock loss is massive, estimating along with his colleagues that it is about one billion cubic kilometers (200 million cubic miles) of pre-Cambrian material is missing based on what would be expected to exist.

The study also explains how much of this erosion occurred before the start of the Phanerozoic era as compared to what experts originally thought, and they presented evidence to show crystals from that era have isotopes of hafnium and oxygen.

According to scientists, the glaciers were very common near the equator in the late Proterozoic era. Places like West North America and Southern Australia were tropical back then, and if we were to take a look at the sediments from this era, we would find a mix of all from sand, mud, and gravel to boulders. These deposits are called tillites which are the material left behind by glaciers. This gave birth to the idea of "Snowball Earth" hypothesis. According to this, the world was covered with glaciers completely. Scientists now believe that these cold episodes may have erased some of the geological data from the earth's history.

Moreover, research also says that the "Great Unconformity" also left long-lasting effects on the weather and transported a lot of geological material into the sea. As for the current location of the rocks, it is argued that the glaciers eroded and also washed them out to sea. This filled the sea with Calcium, Potassium, Iron, Phosphorus, and other vital elements that revolutionized life on our planet.