Yukon Geological Survey
102 & 230 - 300 Main St & 91807 Alaska Highway Y1A 2B5 Whitehorse, YT, Canada

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Have you hiked the popular u Zela Man/Fish Lake trail before? Did you know that half of the trail we now hike used to be underwater?! Looking east, across Fish Lake at Mt. McIntyre, the subtle horizontal feature about midway up the hillside is an ancient shoreline (strandline) from former Glacial Lake McIntyre. The glacial lake was impounded in the Fish Lake basin near the end of the last glaciation, when a lobe of ice blocked meltwater drainage to the north. The ridge t...hat the Fish Lake trail initially follows from the trailhead is a recessional moraine marking the position of the ice front as it retreated further to the north. The strandline indicates that the glacial lake was up to 150 m higher than the modern level of Fish Lake. The deeply incised gullies on the same slope (the eastern side of Mount McIntyre) were meltwater channels draining the lateral margins of an ice lobe that filled the Yukon River valley to the east. Hiking directions and descriptions can be found at Yukon Hiking: https://www.yukonhiking.ca/fish_lake.html

Since that white stuff is starting to appear on the mountain tops, let's talk about White Mountain! (ba-dum-cha ) This hike is a challenging hike up into the alpine that yields great views of Little Atlin Lake and even Atlin Lake once you gain elevation. The trailhead is off of the Atlin Road. Mount White is made up of limestone of the Cache Creek terrane. (A terrane in geology is an expanse of crust formed on one tectonic plate and attached to the crust of another tectoni...c plate.) The Cache Creek terrane probably originated in Panthalassa (which translates as the World Ocean), an ancient superocean that existed during the time of the supercontinent Pangea. The limestone of Mount White may have formed as a coral atoll on top of a seamount in the Panthalassa Ocean (Figure 1). The Cache Creek seamount and coral atoll slowly moved thousands of miles through plate tectonics and eventually crashed into Ancient North America 180 to 170 million years ago. See https://www.yukonhiking.ca/mount_white.html for more detailed information about the Mount White hike itself.

Our Head of Surficial Geology, Jeff Bond, talks about the Sunnydale slide in Dawson City

Here are a few photos of the washouts that occurred along the Alaska Highway at the south end of Kluane Lake between Silver Creek and Slims River on August 17th. The steep rock gullies on the north flank of Outpost Mountain are highly susceptible to debris flows, particularly after heavy rainfall which saturates the soil and causes a rapid loss of soil strength. Rockfall and small alpine permafrost-related landslides also contribute to ongoing accumulation of sediment in the... upper gully catchments. This material is periodically flushed out by debris flows after intense rainfall. There is a long history of rainfall-triggered debris flows impacting the Alaska Highway in this area. In 1967, the highway was closed by a debris flow originating from the same drainage as Slide #1. In July 1988, multiple washouts also occurred in this area, including the Slide #2 drainage, resulting in a 5-day highway closure after a prolonged period of heavy rainfall. It's not a surprise that these washouts occurred this year considering the exceptionally wet spring and summer Burwash Landing (located approximately 50 km to the north) has experienced this year. Monthly precipitation recorded there has been more than double normal amounts for May (228%), July (217%) and August to date (284%). 32 mm of rain was recorded there in one day alone on August 14 (43 mm is the monthly normal for August)! : Crey Ackerson, a Simon Fraser University MSc student who is partially funded by YGS this year to investigate the surficial geology and Quaternary history of the southwest Kluane Lake area.

The YGS is pleased to announce the release of an aeromagnetic survey of the Nash Creek area, Yukon, parts of NTS 105M & N, 106C & D, 115P and 116A, by F. Kiss of the Geological Survey of Canada. The data and maps are available in Yukon Geological Survey Open File 2020-7 (GSC Open File 8728), and can be downloaded here: http://data.geology.gov.yk.ca/Reference/95875#InfoTab This survey was funded by phase 2 of the Geo-Mapping for Energy and Minerals program (GEM-2) of the Lands and Minerals Sector, Natural Resources Canada.

Tombstone Rocks looked a little different this year, but our friends at the Tombstone Territorial Park made this great video about our visit. Check it out!

We have released our lithogeochemistry data set! The lithogeochemical data provide the chemical composition of rock samples. These data help characterize the rocks and can be used to understand their mode of formation. The data can be downloaded from: http://data.geology.gov.yk.ca/Compilation/35#InfoTab or ... https://mapservices.gov.yk.ca/GeoYukon/ If you have any questions about the content of this data set, please contact [email protected]

Thanks to Doug Rutherford for sharing this beautiful watercolour he painted, which was inspired by the Tors Hike we posted about in May! Do you have a geological landscape that inspires your inner artist? Please share your creations with us!

Julia’s many accomplishments in a short and brilliant career, had a significant impact on Yukon projects and people. She was an amazing advocate for AC, ATAC, Y...ukon, as well as women in mining, who she stood out as a role model for, not through any specific intention, but by embodying what it means to be professional, accomplished, passionate and dedicated to your work, engaged with the people you work with, and an advocate for the Industry she was an integral part of. Today we remember losing one of our own, an exceptional geologist, a rising star, an extraordinary leader and a great friend.

Recently, staff from Yukon Geological Survey made a trip to Tombstone Territorial Park a very popular destination for Yukoners and non-Yukoners alike! Rocks within Tombstone Park record over 1.8 billion years of Earth’s history. Some of the oldest rocks you will see initially formed from sediments deposited on shallow water platforms and deep ocean basins at the western edge of ancient North America. Near North Fork Pass, you will find outcrops of volcanic rocks that formed... as submarine lava flows that erupted from cracks in the ocean basin. But what really stands out in the park are the spectacular mountains which resulted from enormous compressional forces beginning roughly 180 million years ago as the western edge of Ancient North America collided with fragments of oceanic and continental crust drifting in from the ancestral Pacific Ocean. Compressional forces (squeezing) created extensive thrust faults that pushed thick packages of older rocks northwestward on top of younger rocks. Towering above all of this, is the majestic Tombstone Mountain consisting of resistant igneous rock known as syenite. This rock formed as magma rose slowly through the overlying and surrounding sedimentary rocks around 92 million years ago. The magma cooled slowly allowing time for the growth of large mineral crystals of potassic feldspar. Million years of weathering and erosion have now exposed these impressive syenite peaks. As impressive as these landscapes are, it is the smallest features in the rocks that give geologists the clues to past environments. Have a look at these images to learn about some fascinating geological features found in the rocks beneath your feet. See more

Have you ever wondered about the Carcross desert? Is it reeeeeally a desert? Let Panya Lipovsky, one of our excellent Surficial geologist tell you more in this great Weather Network video! https://www.theweathernetwork.com//sharevideo/61/forecasts

Check out this very cool video The Weather Network did on the Takhini thaw slump https://www.theweathernetwork.com//sharevideo/6175671408001