Black Canyon of the Gunnison (NP #39), Colorado

This canyon is unreal.



I arrived at Black Canyon of the Gunnison National Park (map / wiki) the afternoon (9/22/15), and only the top few hundred feet of the 2,000 foot canyon were in direct sunlight.

 

The rock is maroonish brown with tan intrusions (wiki) that look like lightning. The depths of the canyon are a shaded muddy black. The Gunnison River was only viewable from certain points along the rim and, it stood out against the darkness as a roiling sliver of green tinted turbulence. Its roar could be heard.

 

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Black Canyon of the Gunnison is so named because sunlight doesn’t often penetrate its depths. (Anyone else see a mans face on the wall to the far left?)

 

In the upper canyon ravens effortlessly strafe the sun bathed walls.

 

Erosion has created thin stone fins perpendicular to the canyon, and the raven shadows bounce out on these fins and dive into the crevasses. The raven’s throaty call echos up from the depths even more wretched than the original. Lower in the canyon swallows and swifts the size of stout cigars dart around snapping up early evening insects. A handful flew by me at eye level before diving down to the feast. Their wing beats are sharp enough to be heard over the wind and river.

 

This canyon is like nothing I’ve ever seen. 

 

To quote geologist Wallace Hansen,

 


“Several western canyons exceed the Black Canyon in overall size. Some are longer, some are deeper, some are narrower, and a few have walls as steep. But no other canyon in North America combines the depth, narrowness, sheerness, and somber countenance of the Black Canyon of the Gunnison”.


 

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That’s the Gunnison River in the center.

 

In 48 miles the Black Canyon of the Gunnison looses more elevation than the 1,500 miles of the Mississippi from Minnesota to the Gulf of Mexico.

 

But why so steep? Shouldn’t the river just go around?

 

The way I understand it is like this: 1.7 billion years ago the rock that would become the strong walls of the canyon was formed as metamorphic rock. The original brown (gneiss and schist) layer solidified and then fractured allowing the tan (pegmatite) intrusion dikes to enter the cracks and solidify. Fast forward more than 1.6 billion years (1/3 the age of the earth), and a period of volcanic activity created a walled off “cul-de-sac” watershed with the only outlet being toward the north. From the foothills of the volcanoes the watershed sloped gently, and the general route of the Gunnison River was laid down as an unassuming valley. Then as recently as 2-3 million years ago the area underwent broad uplift. The slope of the watershed increased, and the river continued to cut deeper and deeper as the original metamorphic formation was thrust upwards. The Gunnison River dug down into the rising rock at a rate of 1″ per 100 years [math check: 2,000,000 years * (1 inch / 100 yrs) * (1 foot / 12 inch) = 1,667 feet of erosion over 2 million years].

 

The interesting part is that if the predecessor to the Gunnison river hadn’t begun to erode the blueprint of the Black Canyon before the uplift, the river likely would have followed a path of least resistance around the uplift. However, as the uplift occurred the path of least resistance continued to be the route originally determined by the gentle slope.

 


 

I hiked down into the canyon the next day. It was steep, loose, sketchy, and totally worth it.

 

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The texture of the canyon is only brought out with the right angle of sunlight.

 

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Here’s a shot of the dark gneiss and/or schist rock with light grainy pegmatite intrusion.

 

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There were these translucent flakes of muscovite micah that formed with the pegmatite. I kept mistaking them for plastic trash on the trail.

 

That’s all folks! Have a juniper in silhouette!

 

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4 Comments on “Black Canyon of the Gunnison (NP #39), Colorado

  1. Hey Jay, sweet blog. Your brother informed me of your website in our last conversation. My wife and I have been following it for a couple months since we’re on a similar trip. I’ve been waiting to see if we ever cross paths, and perhaps run into each other. I may be too late, but if you’re headed towards Golden/Denver/Rocky Mtn. NP/ Fort Collins, it’d be fun to meet and share some conversation.

    1. Hey my brother was telling me about your trip! Unfortunately, I’m headed back through southern Utah right now towards CA. I’ll be retracing your path through Capitol Reef, Bryce, and Zion.
      Holy cow – I just looked at your maps on your website and we are doing a SUPER similar trip! How long do you think you’ll be on the road?

      1. Oh cool! But bummer we won’t be crossing paths again on the road. We thought it was pretty crazy too how we came up with such similar trips without knowing each other! Our plan is to be home by the end of October.

        1. Yeah I kept looking at the maps and thinking “no way.. NO WAY!.”
          It makes me think there are way more of us out there wandering the states than I originally would have guessed.
          Jay

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