The Burgess Shale

Burgess Shale

The Burgess Shale Formation, located in the Canadian Rockies of British Columbia, is one of the world's most celebrated fossil fields, and the best of its kind. It is famous for the exceptional preservation of the soft parts of its fossils...

, a series of fossil

Fossil

Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...

 beds in the Canadian Rockies

Canadian Rockies

The Canadian Rockies comprise the Canadian segment of the North American Rocky Mountains range. They are the eastern part of the Canadian Cordillera, extending from the Interior Plains of Alberta to the Rocky Mountain Trench of British Columbia. The southern end borders Idaho and Montana of the USA...

, was first noticed in 1886 by Richard McConnell of the Geological Survey of Canada (GSC). His and subsequent finds, all from the Mount Stephen

Mount Stephen

Mount Stephen is a mountain located in the Kicking Horse River Valley of Yoho National Park, ½ km east of Field. The mountain was named in 1886 for George Stephen, the first president of the Canadian Pacific Railway....

 area, came to the attention of palaeontologist Charles Doolittle Walcott

Charles Doolittle Walcott

Charles Doolittle Walcott was an American invertebrate paleontologist. He became known for his discovery in 1909 of well-preserved fossils in the Burgess Shale of British Columbia, Canada.-Early life:...

, who in 1907 found time to reconnoitre the area. He opened a quarry in 1910 and in a series of field trips brought back 65,000 specimens, which he identified as Middle Cambrian

Cambrian

The Cambrian is the first geological period of the Paleozoic Era, lasting from Mya ; it is succeeded by the Ordovician. Its subdivisions, and indeed its base, are somewhat in flux. The period was established by Adam Sedgwick, who named it after Cambria, the Latin name for Wales, where Britain's...

 in age. Due to the quantity of fossils and the pressures of his other duties at the Smithsonian Institution

Smithsonian Institution

The Smithsonian Institution is an educational and research institute and associated museum complex, administered and funded by the government of the United States and by funds from its endowment, contributions, and profits from its retail operations, concessions, licensing activities, and magazines...

, Walcott was only able to publish a series of "preliminary" papers, in which he classified the fossils within taxa

Taxon

|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...

 that were already established. In a series of visits beginning in 1924, Harvard University professor Percy Raymond

Raymond

Raymond is a male given name . It was borrowed into English from French...

 collected further fossils from Walcott's quarry and higher up on Fossil Ridge, where slightly different fossils were preserved.

Interest in the area's fossil beds faded after Raymond's 1930s expeditions. In the early 1960s Harry B. Whittington

Harry B. Whittington

Harry Blackmore Whittington FRS was a British paleontologist based at the Department of Earth Sciences, Cambridge, and was affiliated to Sidney Sussex College. He attended Handsworth Grammar School in Birmingham, followed by a degree and Ph.D in geology from the University of Birmingham...

 was persuaded that further investigation was required, and organised surveys in partnership with the Geological Survey of Canada. These new specimens led him to set up a team to re-examine Walcott's fossils, which had languished in a store-room at the Smithsonian since Walcott's death in 1927. In the early 1970s the team published papers that diagnosed many of the specimens as fossils of previously unknown types of animals, some possibly belonging to new phyla

Phylum

In biology, a phylum The term was coined by Georges Cuvier from Greek φῦλον phylon, "race, stock," related to φυλή phyle, "tribe, clan." is a taxonomic rank below kingdom and above class. "Phylum" is equivalent to the botanical term division....

. These analyses heightened interest in the existing debate about whether the Cambrian explosion

Cambrian explosion

The Cambrian explosion or Cambrian radiation was the relatively rapid appearance, around , of most major phyla, as demonstrated in the fossil record, accompanied by major diversification of other organisms, including animals, phytoplankton, and calcimicrobes...

 represented a truly abrupt evolution of recognisable animals or was the result of a longer development, most of which was hidden by gaps in the known sets of fossils that had been found.

All this time no Canadian museum had its own collection of Burgess Shale fossils. In 1975 the Royal Ontario Museum

Royal Ontario Museum

The Royal Ontario Museum is a museum of world culture and natural history in Toronto, Ontario, Canada. With its main entrance facing Bloor Street in Downtown Toronto, the museum is situated north of Queen's Park and east of Philosopher's Walk in the University of Toronto...

 (ROM) began collecting, found 7,750 new specimens around the existing sites, and discovered similar fossil beds up to 40 kilometres (24.9 mi) away. Their collection currently stands at 140,000 specimens and growing, and the rate at which new species are found suggests that the Burgess Shale will continue to produce important discoveries for the foreseeable future.

Early forays

The richness of fossils in the Field area was first identified by workers associated with the construction of the Trans-Canada railway, which had (somewhat controversially) been routed through the Kicking Horse valley. Richard McConnell, of the Geological Survey of Canada, was mapping the geology around the railway line in September 1886, and was pointed to the Mount Stephen trilobite beds

Mount Stephen trilobite beds

The Mount Stephen trilobite beds are a series of fossil strata on Mount Stephen, British Columbia that contain exceptionally preserved fossil material...

 by a construction worker. Several unusual fossils were subsequently described from this site, including sponges, worms, and the appendages of the unusual Anomalocaris, identified at that time as the bodies of crabs. Some of these fossils found their way to Charles Doolittle Walcott, who described them and correctly estimated their Middle Cambrian age. These fossils whetted Walcott's appetite for the region, but it was not until 1907 that the opportunity arose for him to visit Mount Stephen in person.

1908 saw a rich crop of publications as Walcott worked on the material he had collected the previous year, and towards the end of August 1909 he returned to the Field area. That summer, Walcott had visited England to participate in the celebration Darwin

Charles Darwin

Charles Robert Darwin FRS was an English naturalist. He established that all species of life have descended over time from common ancestry, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection.He published his theory...

's centenary. Whilst there, he had met the Natural History Museum curator Henry Woodward, who had suggested that the nearby Mount Field may yield further fossils of the ilk of the Trilobite beds. Promptly upon his arrival in Field, Walcott ascended the slopes of Mount Field via Burgess Pass. This pass, probably one of the many constructed by the CPR in an effort to attract tourists, led along what is now called Fossil Ridge. Walcott recognised the talus material which lay across the trail as the Stephen Formation, and noticed interesting fossils. This find is often considered to be the first discovery of the Burgess Shale 'proper'. He spent several more days collecting on Fossil Ridge before returning to Mount Stephen to bolster his collections from the Trilobite Beds.

The subsequent year saw more intensive collecting by Walcott. He and his two sons systematically investigated every stratum of rock to locate the source of the block they had found the previous summer. They eventually identified the productive layers, including the Phyllopod bed

Phyllopod bed

The Phyllopod bed, designated by USNM locality number 35k, is the most famous fossil-bearing member of the Burgess shale fossil lagerstatte. It was quarried by Charles Walcott from 1911–1917, and was the source of 95% of the fossils he collected during this time;tens of thousands of...

, in what would become the Walcott Quarry. They began to excavate this outcrop, sending blocks by pack horse to Walcott's wife, who split the shale and prepared fossils for transportation downhill to Field, and onwards by rail to Washington. While reporting his finds in the following year, Walcott first coined the term 'Burgess Shale', proposing it to form a facies within the Stephen Formation. These reports covered many now-familiar animal genera, although few of Walcott's proposed classifications would stand the test of time; they were also Walcott's final publications on Burgess Shale animals.

Walcott and his family returned to the quarry each summer until 1913, using dynamite as surface collection dried up. During this time, his wife and eldest son both died – in a train crash, and to tubercolosis, respectively. He considered his next trip, in 1917, to have "practically exhausted" the quarry, with 1300 kg of material being collected that year. He returned to take additional collections, mainly from talus material, in 1919, 1921, and 1924, amassing a total of 65,000 fossil specimens over 30,000 slabs. During these years, he made further preliminary descriptions of the less glamorous sponges and algae. He photographed and clearly intended to describe many further taxa, many of which sat alone with their photograph in a Smithsonian drawer for decades after Walcott's death. Unfortunately, administrative duties became a growing burden on Walcott's time, and the Burgess took a back seat to the completion of his attempts to document the stratigraphy of the southern Rockies, an extensive work which he did not live to see published.

Three years prior to Walcott's death in 1927, the Harvard University professor Percy Raymond led a group of summer-school students to Walcott's camp and quarry. These field trips became a regular fixture, and Raymond's interest in the fossils led him to obtain permission to re-open the quarry. He also determined that a level slightly further up-slope, recognised but not exploited by Walcott, bore a slightly different fauna, and opened a new quarry – now termed the Raymond Quarry – at this level.

Renewed interest

After Raymond's few excursions, the Burgess Shale faded somewhat into obscurity. Walcott's third wife, Mary Vaux, discouraged access to the collections, which gathered dust on high shelves in the Smithsonian Institution. Harry Whittington, then of Harvard University, was to prove the catalyst that renewed interest in the site. As he showed a visiting trilobite expert around Raymond's collections, the necessity of a restudy was pointed out to Whittington, who proceeded to lobby the Geological Survey of Canada (GSC) to revisit the locality. They did, and as a leading authority on trilobites, Whittington was the logical choice to head the palaeontological investigations in the arthropod-rich Shale. In the company of Jim Aitken and Bill Fritz, he led a GSC reconnaissance expedition in 1966; fellow trilobitologist David Bruton joined the crew the next year as they went out to quarry in force. Dynamite was used in only the smallest quantities, with closely spaced drill holes used to separate large blocks of rock, and large slabs were collected systematically from the Walcott and Raymond quarries. These were labelled with their stratigraphic level, helicoptered from the mountain face, and returned to Whittington's base at the Sedgwick Museum in Cambridge for further study. The 1967 operation resulted in the description of new animals, including the earliest known crinoid and a complete Anomalocaris. Initially, detailed descriptions were made of some of the most common arthropod-like organisms: Marrella, Sidneyia and Burgessia. These redescriptions were slow and laborious, making extensive use of the camera lucida

Camera lucida

A camera lucida is an optical device used as a drawing aid by artists.The camera lucida performs an optical superimposition of the subject being viewed upon the surface upon which the artist is drawing. The artist sees both scene and drawing surface simultaneously, as in a photographic double...

 technique for microscope drawing, with papers based extensively around detailed drawing of the fossil specimens. It soon became clear that the Burgess Shale was even more exceptional than previously thought - soft tissue was preserved to an exquisite quality, allowing insights into early life that had never before been dreamed of, and preserving a range of non-mineralising taxa which are otherwise invisible in the fossil record. With an overwhelmingly diverse fauna in need of cataloguing, Harry Whittington set his two new graduate students to the task, assigning Derek Briggs

Derek Briggs

Derek Ernest Gilmor Briggs is an Irish paleontologist and taphonomist based at Yale University. Briggs is one of three paleontologists who were key in the reinterpretation of the fossils of the Burgess Shale.-Professional achievements:...

 and Simon Conway Morris

Simon Conway Morris

Simon Conway Morris FRS is an English paleontologist made known by his detailed and careful study of the Burgess Shale fossils, an exploit celebrated in Wonderful Life by Stephen Jay Gould...

 the arthropods and 'worms', respectively. This work began to lift the veil on an unexpectedly diverse ecosystem, with almost as much variety as seen in the modern oceans - the old theory that Cambrian life was simple, straightforwards and slightly dull disintegrated further with each new fossil described. This view was reinforced with the identification of other Burgess Shale-type deposits elsewhere in the world, a search for which was triggered by the discovery of the Chengjiang and Sirius Passet

Sirius Passet

Sirius Passet is a Cambrian Lagerstätte in Greenland. The Sirius Passet Lagerstätte was named after the Sirius sledge patrol that operates in North Greenland. It comprises six localities located on the eastern shore of J.P. Koch Fjord in the far north of Greenland. It was discovered in 1984 by A....

 lagerstätten in 1984.

Canadian collections

Until 1975, no Canadian museum had its own collection of Burgess Shale fossils. With the work of the GSC and its associates, the shale was rising to prominence, and in 1975 the Royal Ontario Museum

Royal Ontario Museum

The Royal Ontario Museum is a museum of world culture and natural history in Toronto, Ontario, Canada. With its main entrance facing Bloor Street in Downtown Toronto, the museum is situated north of Queen's Park and east of Philosopher's Walk in the University of Toronto...

 (ROM) obtained permission from the National Parks authority, Parks Canada

Parks Canada

Parks Canada , also known as the Parks Canada Agency , is an agency of the Government of Canada mandated to protect and present nationally significant natural and cultural heritage, and foster public understanding, appreciation, and enjoyment in ways that ensure their ecological and commemorative...

, to collect fossils from talus material in order to develop its own display. Parks Canada would redirect other museums' requests for material to the ROM, so the 1975 collection team gathered ample specimens to meet the anticipated teaching and display requirements. As well as 7750 specimens, this expedition yielded evidence that further fossil outcrops existed up-slope, and in 1981 a five-year reconnaissance program begun. This program would unearth further sites higher on Fossil Ridge; further around the steep cliffs of Mount Stephen; and on Odaray Mountain. These sites proved very productive, bearing a different fauna and spanning more time than the original beds. Excavation by ROM crews continues to this day, and has found fossils below the base of Walcott's quarry, and some 40 km away near the Stanley Glacier. The ROM's collections now stand proud of 140,000 specimens, and is continually yielding important new species and redescriptions. Statistical analysis suggests that new species will continue to be discovered for years to come.

Protection

In 1981, UNESCO

UNESCO

The United Nations Educational, Scientific and Cultural Organization is a specialized agency of the United Nations...

 recognised the importance of the Burgess Shale by naming it a World Heritage site

World Heritage Site

A UNESCO World Heritage Site is a place that is listed by the UNESCO as of special cultural or physical significance...

. Access to the Fossil Ridge quarries and Trilobite beds is now possible only as part of a guided group, and the sites are under continuous surveillance by Parks Canada, with hefty fines for removing or defacing fossil material.

Centenary

To mark the hundredth anniversary of Walcott's discovery of the main Burgess Shale site on Fossil Ridge, an international conference of 150 specialists in the field was held in Banff, Alberta, in August 2009. It featured technical and keynote sessions reporting on the latest research in the field, and field hikes to the Shale itself.