The highlight of Dr. Charles D. Walcott's career occurred in 1909 high above Emerald Lake as he rode below the long ridge connecting Wapta Mountain with Mount Field. A block of shale had tumbled down the slope to the trail and was blocking the trail. Walcott dismounted and was about to tip the slab out of the way but instead reached for his rock hammer and split the slab open. The fossils in this slab and thousands of others from the Burgess Shale formation have challenged the skills and imaginations of palaeontologists ever since. The following year Walcott returned to the area accompanied by his sons Stuart (see Stuart Knob) and Sidney. Together they examined all the layers on the ridge above the point where the fossil laden rock had been found, eventually finding the fossiliferous band. For the next thirty days they quarried the shale and slid samples down the ridge to the trail where they were loaded onto pack horses and made their way to the CPR station at Field. Eventually some 65 000 specimens on 30 000 slabs of rock were delivered to the Smithsonian Institute.