Geology Photo of the Week #15 – Dec 9-15

The 15th photo of the week is of an area of natural acid rock drainage (ARD) in Eagle Plains, Yukon. ARD is a phenomenon that most people associate with mine tailings and mine waste. However, it occurs naturally as well since the only criteria that need to be met are a source of oxidized water, such as rain, rocks or minerals that have a high sulphur content, and a very little carbonate in the rocks. Once you have these three things ARD is very possible, and it occurs naturally all over the world. As you can see at this site the ARD is pretty much killing everything in its path. This is no surprise since the water in the area is about pH 1 or 2 and most things cannot survive such a hostile environment.

That said, a lot of research is going into looking at what an survive in such hostile places and how this might relate to extra-terrestrial life.

The Eagle Plains ARD site. (Photo: Matt Herod)

Dr. Lacelle installing some peepers at the Eagle Plains ARD site. (Photo: Matt Herod)

Thanks for reading!


Matt Herod is a Ph.D Candidate in the Department of Earth Sciences at the University of Ottawa in Ontario, Canada. His research focuses on the geochemistry of iodine and the radioactive isotope iodine-129. His work involves characterizing the cycle and sources of 129I in the Canadian Arctic and applying this to long term radioactive waste disposal and the effect of Fukushima fallout. His project includes field work and lab work at the André E. Lalonde 3MV AMS Laboratory. Matt blogs about any topic in geology that interests him, and attempts to make these topics understandable to everyone. Tweets as @GeoHerod.


  1. I’m puzzled … if ARD is a natural part of the ecology … how did the trees get established in the first place?

    • Hey Hollis,

      Great question!! I had to think about this one for a while. What I did not say in the post is that this site is only a few hundred metres from the Dempster Highway. I suspect that when they were clearing and excavating for the road they uncovered some of the local shale, which has sulphide concentrations through the roof. Once this sulphide starts to oxidize the ARD is produced. Some of the creeks not far from there that I have sampled have SO4 concentrations around 800ppm!

      • ah ha … thanks, Matt, and happy holidays.

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