Conglomerate Mountain Rest Area, Yukon
by Murray Lundberg
Campgrounds and Rest Areas in the Yukon
The Conglomerate Mountain Rest Area is located at Km 298.0 of the North Klondike Highway (measured from Skagway, Alaska). It has outhouses, garbage bins, and interpretive panels.
Northbound at about Km 297, with Conglomerate Mountain (1,024 meters/ 3,361 feet high) on the right.
The Conglomerate Mountain Rest Area. The Km 298 post can be seen on the shoulder, paired with a Trans Canada Trail sign.
The Yukon has two major geological components. The area mainly northeast of Tintina Trench formed the west coast of ancient North America until about 200 million years ago. The remaining half of the Yukon originated elsewhere and was transported, via plate tectonics, to its present position. These transported Yukon terranes can be divided into about 10 large blocks, each of which has distinct geological features. You are standing in what geologists call the Whitehorse Trough.
The area consists of 200- to 170-million-year-old sedimentary and volcanic rocks that formed in a deep-sea basin and adjacent chain of volcanic islands. The rounded conglomerate boulders making up Conglomerate Mountain above you came from the now-eroded volcanic islands laying to the west, and were deposited as gravelly rivers and fan-deltas that spread toward the east. Similar conglomerate deposits extend from south of Atlin, British Columbia, to north of Carmacks, indicating that the Whitehorse Trough basin was at least 600 km long. Fossils in the rock show that this basin was covered by sea water until about 170 million years ago.
In the forest, some blocks of the conglomerate (sometimes called puddingstone) that have broken off the mountain and tumbled down can be found.