Study: Effects of past ice ages more widespread than previously thought

February 22, 2021

FAYETTEVILLE, Ark. - Cold temperatures, prevalent during glacial periods, had a significant impact on past and modern unglaciated landscapes across much of North America, according to a recent study by University of Arkansas geologist Jill A. Marshall.

Marshall, assistant professor of geosciences, is the first author of the study, published in the journal Geophysical Research Letters.

The findings help shape understanding of the earth's "Critical Zone," the relatively thin layer of the planet that extends from where vegetation meets the atmosphere to the lowermost extent of weathered bedrock. "Climate and ecosystems determine how quickly bedrock weathers, how soil is produced, how sediment moves on land and in rivers and other factors that shape the landscape," the authors wrote.

In cold lands, such as Alaska today, frost can crack or weather rock that is at or near the surface of the earth - making it more porous and turning solid rock into sediment. By applying a frost-weathering model to North America paleoclimate simulations tracking temperatures during the Last Glacial Maximum approximately 21,000 years ago, Marshall and her team determined that a large swath of North America, from Oregon to Georgia and as far south as Texas and Arkansas, were likely affected by such periglacial processes.

While permafrost landscapes like the modern Arctic experience frozen ground for two years or more, periglacial landscapes, though not permanently frozen, experience below-freezing temperature for much of the year. Though the evidence of past periglacial processes is easily hidden by vegetation and/or erased by subsequent geological processes, the teams' results suggest that frost weathering (and by extent other periglacial processes) covered an area about 3.5 times larger than the mapped extent of permafrost during the Last Glacial Maximum. This predicted influence of past cold climates on below ground weathering may significantly influence modern landscape attributes that we depend on such as soil thickness and water storage.

"Based on the widespread occurrence of glacial-period frost weathering over meter-scale depths, we suggest that past cold climates have had a significant impact on modern landscapes, both through lingering impact on subsurface pathways for water and thus chemical weathering, and the rock damage that contributes to the rate at which rock disaggregates into sediment and potential instability due to non-steady rates of hillslope and river processes," the paper states.
-end-


University of Arkansas

Related Sediment Articles from Brightsurf:

The first detection of marine fish DNA in sediment sequences going back 300 years
Far too little is known about the long-term dynamics of the abundance of most macro-organism species.

Microbial diversity below seafloor is as rich as on Earth's surface
For the first time, researchers have mapped the biological diversity of marine sediment, one of Earth's largest global biomes.

Climate change could deliver more sediment and pollution to the San Francisco Bay-Delta
Climate change could deliver more silt, sand and pollution to the San Francisco Bay-Delta, along with a mix of other potential consequences and benefits, according to a new study in the AGU journal Water Resources Research.

Urine sediment test results, diagnoses vary significantly across nephrologists
A new study shows that nephrologists do not always agree on their interpretation of images from urine sediment tests, which are frequently ordered to evaluate a variety of kidney diseases.

Texas cave sediment upends meteorite explanation for global cooling
Texas researchers from the University of Houston, Baylor University and Texas A&M University have discovered evidence for why the earth cooled dramatically 13,000 years ago, dropping temperatures by about 3 degrees Centigrade.

Model links patterns in sediment to rain, uplift and sea level change
In a recent study, researchers from The University of Texas at Austin show that a natural record - sediments packed together at basin margins - offers scientists a powerful tool for understanding the forces that shaped our planet over millions of years, with implications on present day understanding.

Massive seagrass die-off leads to widespread erosion in a California estuary
The large-scale loss of eelgrass in a major California estuary -- Morro Bay -- may be causing widespread erosion.

Revealed from ancient sediment: Mangrove tolerance to rising sea levels
The growth and decline of mangrove forests during the final stages of Holocene deglaciation offers a glimpse into how the ecosystems will respond to the rapidly rising seas projected for the future, according to a new study.

New sediment record reveals instability of North Atlantic deep ocean circulation
In the future's warmer climate, large, abrupt and frequent changes in ocean ventilation may be more likely than currently assumed, according to a new study.

Study examines the impact of oil contaminated water on tubeworms and brittlestars
A new study published by Dauphin Island Sea Lab researchers adds a new layer to understanding how an oil spill could impact marine life.

Read More: Sediment News and Sediment Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.