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Fossils about 508 million years old, discovered in 1909Reputable sourceWell documented

Charles Walcott finds the Burgess Shale

On the timeline · around Fossils about 508 million years old, discovered in 1909 · The Preserved WindowsThe Preserved WindowsThe New Cast of AnimalsCharles Walcott finds the Burgess Shale

What happened

On August 30, 1909, Smithsonian administrator and geologist Charles Walcott, riding the high slopes of the Canadian Rockies near what is now Yoho National Park, spotted a loose slab of shale containing fossils unlike anything he had cataloged before. He returned the following year with his family and worked the resulting quarry almost every summer until 1924, eventually extracting some 60,000 specimens now held at the Smithsonian Institution. What made the site extraordinary was not just its age of roughly 508 million years, but its preservation: soft body parts, gills, guts, and delicate limbs that almost never survive fossilization were flattened and preserved as carbon films, revealing animals whose entire soft anatomy would otherwise have vanished without a trace.

Why it matters

Without soft-tissue preservation, the Cambrian would look almost empty, a scatter of shells and fragments. The Burgess Shale is the site that first showed paleontologists the real scale and strangeness of Cambrian animal diversity, and it remains one of the primary windows onto that world more than a century after Walcott's discovery.

How we know

The fossils are direct physical specimens, tens of thousands of them, housed and still studied at the Smithsonian and the Royal Ontario Museum. Their exceptional preservation is explained by rapid burial in fine underwater mudslides that sealed the animals off from oxygen and scavengers before decay could destroy their soft tissue.

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Part of a timelineThe Cambrian Explosion9 events · How nearly every animal body plan alive today appeared within a geological blink, from the first mineral skeletons to the apex predators, calcite eyes, and first fish the fossil record preserves.View all →
Charles Walcott finds the Burgess Shale · The Cambrian Explosion · SourcedStory