Burgess Shale

British  

noun

1. a bed of Cambrian sedimentary rock in the Rocky Mountains in British Columbia containing many unique invertebrate fossils

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Burgess Shale Scientific  

/ bûr′jĭs /

1. A rock formation in the western Canadian Rockies that contains numerous fossilized invertebrates from the early Cambrian Period.

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Burgess Shale Cultural  

1. A famous rock formation in the western Canadian Rockies, containing unusually well-preserved fossil invertebrates of the early Cambrian Period (from about 540 million years ago). The Burgess Shale fossils provide valuable information about the evolution of early life on Earth.

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Closer Look

Animals in the period known as the Cambrian Explosion sported bizarre combinations of legs, spines, segments, and heads found in no present-day animals. Many of these animals became extinct, leaving no descendants, whereas others may have evolved into groups that are familiar to us today. Most of our knowledge about these early life forms comes from the Burgess Shale, a 540-million-year-old formation of black shale discovered in 1909 by Charles Walcott in the Rocky Mountains of British Columbia. The unique process of fossilization that occurred in the Burgess Shale allowed exquisite preservation of these early animals. While in most cases a reaction to oxygen causes the soft parts of animals to rot away prior to fossilization, the Burgess Shale animals were killed instantly by a mudslide deep in the ocean, where there is a lack of oxygen. After burying the animals, the mud hardened into shale, preserving the soft animal parts. At the time of his discovery, Walcott was able to classify the fossils as ancestors of modern animals. The Burgess Shale was reexamined in the mid-1960s, and many new, unknown fossils were found. When Harry Whittington, Derek Briggs, and Simon Conway Morris studied these new fossils in the 1970s and 1980s, they realized that many of them did not fit into the modern classification system. The implication that there were more basic animal forms in the Cambrian Period than there are today shook up traditional ideas about evolution. In 1989 Stephen Jay Gould brought the Burgess Shale to wide public attention with the publication of his book Wonderful Life.

Etymology

Origin of Burgess Shale

named after the Burgess Pass, where the bed is exposed

Example Sentences

Han said his team was also surprised that some of the animals in the quarry had also been found at Canada's Burgess Shale site, which dates from an early period of the Cambrian explosion.

From Barron's • Jan. 28, 2026

Only a dozen species have known complete appendages, yet most of those are preserved as highly compressed, flat fossils, as is seen in the Burgess Shale from British Columbia.

From Science Daily • Dec. 21, 2023

Because of the conditions in the Burgess Shale, which was likely buried rapidly in an underwater mudslide, many soft tissues like brains, eyes and digestive organs were preserved.

From Salon • Aug. 2, 2023

The Welsh quarry, he says, “could definitely be as famous” as the Burgess Shale.

From Science Magazine • May 1, 2023

Of all the strange creatures unearthed from the Burgess Shale — a cache of remarkable Cambrian fossils deposited in the Canadian Rockies — none has been quite as transfixing as Opabinia.

From New York Times • Feb. 8, 2022