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Grand Canyon's Missing Geologic Record Linked to Giant Ancient Cliff

Scientists propose a massive, continent-spanning cliff and a global glaciation event may explain a billion-year gap in the Grand Canyon's geologic history.

The Grand Canyon preserves rock layers dating back about 2 billion years, but a significant period between 520 million and 1.8 billion years ago is missing. Researchers suggest a colossal cliff, formed as the supercontinent Rodinia split apart around 800 million years ago, is responsible for this erosion.

Computer models simulated how this ancient cliff, or escarpment, likely stretched across Laurentia (precursor to North America) for thousands of kilometers, reaching one to two kilometers in height. This immense geological feature created steep slopes vulnerable to weathering and erosion.

The erosion was amplified by a period of extreme glaciation known as Snowball Earth, where massive ice sheets may have extended to equatorial regions. The expanding ice further eroded rock, contributing to the gap in the geologic record.

The high elevation of the escarpment likely provided ideal conditions for Snowball Earth glaciers to form, acting as 'glacier factories.' A similar escarpment has been linked to the formation of the East Antarctic Ice Sheet.

It is currently unclear whether the erosion occurred before, during, or after the Snowball Earth glaciations. Pinpointing the precise timing and location of this erosion across continents remains a key area for future research.

The theory is supported by linking the rock disappearance to verified events like Rodinia's breakup and by observing similar erosive processes at modern escarpments in Antarctica and South Africa.

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