Scientists now know what happened to a chunk of Earth’s crust missing for millions of years

Scientists have recently unravelled the mystery of "The Great Unconformity," a phenomenon where large sections of the Earth's crust are missing from the geological record.

Experts have now concluded that this gap most likely emerged from the intense glacial erosion during a period known as "Snowball Earth," when much of the planet was covered in ice.

Glacial erosion led to gap in sedimentary record

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The process of glacial erosion, occurring during this ancient time, led to a significant removal of rocks, creating a gap in the sedimentary record.

This geological oddity was first observed in 1869 at the Grand Canyon in Arizona when experts noticed a sudden change in the age of rocks, a pattern found in various locations globally.

A recent study estimated that an astonishing 3-5 kilometres of rock globally were eroded due to glacial activity, leaving a billion cubic kilometres of pre-Cambrian material missing from records.

The pre-Cambrian refers to the earliest part of Earth's history.

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Dr Brenhin Keller, the lead author of the study, highlighted the colossal scale of rock loss.

His theory proposes that more extensive erosion occurred before the Phanerozoic era than previously believed.

The Phanerozoic is the current and the latest of the four geologic eons in the Earth's geologic time scale, covering the time period from 538.8 million years ago to the present.

Evidence, including isotopes of hafnium and oxygen found in crystals from that era, supports the idea that these materials were eroded from old rock and deposited at low temperatures.

Their theory also suggests this is why there are many asteroid craters less than 700 million years old and only two that are dated older than that.

Current whereabouts of the missing rock

The researchers argue that glaciers responsible for eroding sedimentary rocks also carried them to the sea, providing a possible explanation for the current whereabouts of the missing rocks.

This discovery sheds light on Earth's ancient history and the dynamic processes that have shaped its geological landscape.

(With inputs from agencies)