Free Wonderful Life: The Burgess Shale and the Nature of History by Stephen Jay Gould Page B

[locality of the Burgess Shale]. Helena, Helen, Arthur and Stuart [his wife, daughter, assistant, and son] came up with remainder of outfit at 4 P.M .

    2.5. Walcott in his seventies, during one of his last Western field seasons. He stands with his horse, reminding us of the legend of the discovery of the Burgess Shale.
    The next day, they had obviously discovered a rich assemblage of soft-bodied fossils. Walcott’s quick sketches (figure 2.6) are so clear that I can identify the three genera depicted: Marrella (upper left), one of the unclassifiable arthropods; Waptia (upper right); and the peculiar trilobite Naraoia (lower left). Walcott wrote: “Out with Helena and Stuart collecting fossils from the Stephen formation. We found a remarkable group of phyllopod crustaceans. Took a large number of fine specimens to camp.”
    What about the horse slipping and the snow falling? If this incident occurred at all, it must have been on August 30, when his family came up the slope to meet him in the late afternoon. They might have turned up the slab as they descended for the night, returning the next morning to find the specimens that Walcott sketched on August 31. This reconstruction gains some support from a letter that Walcott wrote to Marr (for whom he later named the “lace crab” Marrella ) in October 1909:
    When we were collecting from the Middle Cambrian, a stray slab brought down by a snow slide showed a fine phyllopod crustacean on a broken edge. Mrs. W. and I worked on that slab from 8 in the morning until 6 in the evening and took back with us the finest collection of phyllopod crustaceans that I have ever seen.
    Transformation can be subtle. A previous snowslide becomes a present snowstorm, and the night before a happy day in the field becomes a forced and hurried end to an entire season. But, far more importantly, Walcott’s field season did not finish with the discoveries of August 30 and 31. The party remained on Burgess ridge until September 7. Walcott was thrilled by his discovery, and he collected with avidity every single day thereafter. Moreover, although Walcott assiduously reported the weather in every entry, the diary breathes not a single word about snow. His happy week brought nothing but praise for Mother Nature. On September 1, he wrote: “Beautiful warm days.”

    2.6. The smoking gun that disproves the canonical story for the discovery of the Burgess Shale. Walcott sketched three Burgess genera on August 31 and then continued to collect with great success for another week.
    Finally, I strongly suspect that Walcott located the source of his stray block during that last week of 1909—at least the basic area of outcrop, if not the phyllopod bed itself. On September 1, the day after he sketched the three arthropods, Walcott wrote: “We continued collecting. Found a fine group of sponges on slope (in situ) [that is, undisturbed and in their original position].” Sponges, containing some hard parts, extend beyond the richest layers of soft-bodied preservation at this site, but the best specimens come from the phyllopod bed. On each subsequent day, Walcott found abundant soft-bodied specimens, and his descriptions do not read like the work of a man encountering a lucky stray block here and there. On September 2, he discovered that the supposed shell of an ostracode had really housed the body of a phyllopod: “Working high up on the slope while Helena collected near the trail. Found that the large so called Leperditia like test is the shield of a phyllopod.” The Burgess quarry is “high up on the slope,” while stray blocks would slide down to the trail.
    On September 3, Walcott was even more successful: “Found a fine lot of Phyllopod crustaceans and brought in several slabs of rock to break up at camp.” In any event, he continued to collect, and put in a full day for his last hurrah on September 7: “With Stuart and Mr. Rutter went up on fossil beds. Out from 7 A.M. to 6:30 P.M. Our last day