The Gog Group underlies the Cambrian rocks where the Burgess Shale fossils are found.
Those of you not wearing a bathing suit and a life preserver would be ill prepared if you somehow found yourself in Yoho National Park in the Cambrian. Beginning in the Early Cambrian (~541 million years ago), sea levels rose and flooded coastal regions of ancient North America. Land plants had not yet evolved and erosion rates were high on the vegetation-free continent, reducing the landmass to low relief.
Vast deposits of beach sand were the first Cambrian sediments lain down on the eroded Precambrian bedrock. Tides were more extreme in the Cambrian, and the tidal cycles worked and reworked the beach sediments. The final result was the spectacular sandstones of the Gog Group, over two kilometres thick, composed almost entirely of quartz. In the photo above, the rock behind the guide is sandstone and quartzite of the Gog Group. Although these sandstones are largely covered in the Kicking Horse Valley, most of the popular hikes in the Lake Louise and Moraine Lake areas are almost entirely on rocks of the Gog Group.
Revised for web format from “A Geoscience Guide to the Burgess Shale” by Murray Coppold and Wayne Powell, © The Burgess Shale Geoscience Foundation. To purchase this book, please go to: the Yoho National Park Visitors Centre, Alpine Book Peddlers, Amazon.ca, or Amazon.com