Tillite
“A glacier's fossilized footprint”
Tillite is a sedimentary rock formed from lithified glacial till — the unsorted mix of clay, sand, gravel, and boulders deposited directly by glaciers. Ancient tillites provide crucial evidence for past ice ages, some dating back over two billion years.
variable: unsorted mix of quartz, feldspar, rock fragments of all sizes, clay matrix
Dwyka Group (South Africa), Flinders Ranges (Australia), Gowganda Formation (Ontario, Canada), Namibia
Variable
Tillites found in the Sahara Desert and tropical Africa prove that these regions were once covered by massive ice sheets during the 'Snowball Earth' events ~700 million years ago.
Test Your Knowledge
How do geologists use tillites to reconstruct the positions of ancient continents?
Related Specimens
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