Tempestite
“Ancient storm layers preserved in stone”
Tempestite is a sedimentary bed deposited by major storm events — hurricanes, typhoons, or powerful winter storms — that reworked shallow sea floor sediment into distinctive graded, shell-rich layers. Each tempestite bed records a single catastrophic storm event frozen in the geological record.
calcite (shell fragments), quartz sand, clay minerals, heavy minerals, fossil debris
Jurassic limestones (England), Appalachian Devonian (USA), Cretaceous Interior Seaway (USA), modern hurricane-prone shelves worldwide
3-5
By counting and analyzing tempestite layers in ancient rock sequences, geologists can reconstruct storm frequency over millions of years — revealing that some past periods had far more intense storm activity than today.
Test Your Knowledge
How can geologists distinguish a tempestite from a turbidite, given that both are event beds with graded bedding?
Related Specimens
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