Great Salt Lake's Ancient Past Reveals Fast Disappearance of Fresh Water

Topic: Earth Science

Scientists studied sediments at Great Salt Lake and found that it was once a massive freshwater lake. The lake swelled to nearly 1,000 feet deep and covered over 10 times its current area twice in the past 240,000 years.

A team of researchers from the University of Southern California (USC) Dornsife College of Letters, Arts and Sciences studied sediments buried beneath Great Salt Lake. They reconstructed nearly 240,000 years of lake history and found that two giant lakes appeared in the past, each lasting only briefly. The scientists used a sediment core drilled from the lake's bed in 2000 to analyze the layers of sediment. They dated the layers by measuring radioactive decay in minerals, which acts as a geological clock. The researchers also analyzed molecules left behind by microorganisms that once lived in the lake. This helped them understand whether the water was fresh, brackish or extremely salty.

The record shows two major interruptions in the lake's long hypersaline history. From roughly 30,000 to 16,000 years ago, it expanded to become Lake Bonneville. Little Valley, an earlier deep lake, existed roughly 140,000 to 135,000 years ago. Shoreline evidence suggests both approached 1,000 feet deep.

The scientists compared the two fresh lake events for their duration and freshness, finding that these moments are fragile and fleeting.

Why It Matters

This study is important because it shows how quickly freshwater can disappear in a region with changing climate. This can help us understand the impact of climate change on water resources in India, where many regions face similar challenges.

Key Facts

• The Great Salt Lake was once a massive freshwater lake that swelled to nearly 1,000 feet deep and covered over 10 times its current area twice in the past 240,000 years.
• The researchers used a sediment core drilled from the lake's bed in 2000 to analyze the layers of sediment.
• They dated the layers by measuring radioactive decay in minerals, which acts as a geological clock.
• The record shows two major interruptions in the lake's long hypersaline history: Lake Bonneville and Little Valley.
• Shoreline evidence suggests both lakes approached 1,000 feet deep.

Key Terms

Hypersaline

Extremely salty water

Brackish

Water that is not fresh but also not extremely salty

Implications

This study is important because it shows how quickly freshwater can disappear in a region with changing climate. This can help us understand the impact of climate change on water resources in India, where many regions face similar challenges.