09/14/2026
As part of a weekend filled with educational geology events in Tombstone Territorial Park (Ddhäl Ch'èl Cha Nän), Yukon Geological Survey geologists led a series of guided hikes.
The geologists led a hike on the Goldensides trail, just north of the Tombstone Interpretive Centre and campground on August 22.
Along the trail, geologists showed the hikers examples of shale, a sedimentary rock that formed more than 400 million years ago from mud deposited in a deep ocean basin off the western edge of the ancient North American continent and what geologists refer to as ‘Laurentia.'
Further up the trail, the hikers encountered chert, which also formed on the ocean floor, but in this instance the mud was rich with the skeletons of microscopic creatures known as radiolarians. Radiolarians have shells composed of silica (the main component of the mineral quartz) and when they died, their skeletons rained down forming a silica-rich mud known as ‘siliceous ooze’. This mud eventually hardened into the very hard rock called chert. Chert was historically prized by Yukon First Nations for toolmaking due to its hardness and breaking pattern (it breaks like glass with very sharp edges).
The hike also provided a good viewpoint over the North Klondike valley where the effects of the most recent McConnell glaciation that reached its peak ice coverage 16,000 years ago could be seen.
On a walk from the Tombstone campground down the Klondike River Trail attendees learned the basics of rock identification. Geologists helped them pick their favourites from the bed of a seasonal river channel to learn more about their composition and physical properties. To do this, members of the public observed the rocks in detail using hand lenses, a common item in a geologist’s tool kit.
The August 23 hike up the Grizzly Lake trail took participants through a lush, old-growth forest eventually leading to a viewpoint to discuss some different rock units and observe a fold visible in on a mountain ridge. The more recent geologic past was observed through terrain features such as a ridge of large, rounded boulders forming a glacial end moraine. A volcanic ash deposit known as the ‘White River Ash’ could also be seen along the way. This ash was deposited by two main volcanic eruptions that took place around 2000 and 1200 years ago at Mount Churchill in the Saint Elias Mountains near the Alaska-Yukon border. These eruptions were the largest global eruptions in the last 2000 years, spewing ash across vast areas of Alaska and western Canada; it can also be seen in microscopic amounts in soils as far as western Europe.
The Yukon Geological Survey would like to extend our thanks to everyone who participated and especially to the Tombstone Territorial Park staff.
