Day 15-18 Yellowstone National Park PART II   6 comments

The Upper Falls of the Yellowstone River are amazing. Of course I think all waterfalls are amazing. They are a clue that you are standing at a geological crossroad. A waterfall forms in a river channel where harder rocks meet softer rocks that erode more easily and quickly.

The 109 foot Upper Falls were created by volcanic and hydrothermal activity. About 480,000 years ago, lava formed a layer of rock that resists erosion. The lava naturally cracks in a zig-zag pattern. Over time, hydrothermal springs rose through some of these cracks, altering and weakening the lava. The Yellowstone River flowed through the zig-zag cracks and eroded its river channel. Once the river reached the softer, hydrothermally altered rock, erosion increased and created the Upper Falls.

Here the Yellowstone River plunges 308 feet over the Lower Falls. Hot springs have weakened the rock just downstream, where you might see several geysers spouting into the river.

The Grand Canyon of the Yellowstone is my MOST favorite place to take photos (Grand View). The photos are so beautiful they look fake, like a backdrop.

The canyon varies from 800 to 1200 feet in depth and from 1500 to 4,000 feet in width. Its length is about 24 miles. The upper 2 ½ miles is the most colorful section. Hot spring activity has continued through the ages altering the lava rock to produce lovely colors which are largely due to varied iron compounds. Steam vents and geysers are still at work on the canyon walls.

Here we were inside the caldera of one of the largest volcanoes in the world! The volcano has erupted at least three times, and Yellowstone is full of signs that volcanic activity is still very much alive below ground.

Ten times more acidic than lemon juice, sulphur caldron sits on the edge of one of the most active areas of Yellowstone’s buried volcano. Sulphur-rich gasses rise furiously here, filling sulphur caldron with sulfuric acid. Incredibly, this muddy pool is teeming with life.

On our Wedding Anniversary, we headed out on the motorcycle to see the mouth of the Snake River. Henrys Fork of the Snake River’s primary source is Big Springs, one of the largest freshwater springs in North America. Approximately 120,000,000 gallons of water at 52 degrees flow from the spring daily. The springs and Upper River remain ice-free year round.

Micro-climate – look at the canyon walls directly across and below the falls. You can see that plants growing there are different from those at this location. Mist from the falls and a cool northerly aspect are two factors that help create a micro-habitat which is different than the habitat surrounding the area. This micro-climate allows plants that might not survive here to thrive there.

Upper Mesa Falls is part of the Henry’s Fork of the Snake River. It is approximately 114 feet high and 200 feet wide. The average volume of water flowing over the falls varies between 600 and 1,500 cubic feet per second. This equates to 387 million to 967 million gallons per day.

Lower Mesa Falls is the second-largest undisturbed waterfall on the Columbia River system. The only way to view it close is to hike about 2 miles, so you know we didn’t do that.

On our walk out to the falls, we found a “snow pole.”

Big Springs

Johnny Sack Cabin was built by Johnny in the early 1930s, the 4’11” German immigrant built the entire cabin and furnishings by hand. It was closed so we were unable to see the inside.

The small water wheel built by Johnny was to provide electricity and water to the cabin. The water was pumped up-hill to a cistern and ran by gravity flow through pipes to the cabin.

The nature trail of Big Springs was beautiful. The water was so clear; you could see the fish plain as day.

The best part of all, we spotted a mama moose and her baby.

Earthquake Lake

We were standing atop 300 feet of rock debris, part of a huge landslide triggered by a powerful earthquake that occurred about midnight August 17, 1959. Prior to the earthquake, a buttress of tilted dolomite beds held the canyon wall in place. Behind the supporting buttress was a large mass of weak, older rock – gneiss, schist, and amphibolites.

The earthquake shook the canyon, the supporting dolomite buttress broke and with a roar, the mass of rock behind it hurtled down into the canyon. In less than one minute, over 80 million tons of rock and debris filled the canyon over 300 feet deep. Large dolomite boulders were pushed ahead of the slide and now rest on top of the debris where we stood. These boulders were probably part of that broke buttress, the remnants of which can be seen in the slide area across the canyon.

The huge slide blocked the Madison River near the mouth of the canyon. Immediately, Earthquake Lake began to form behind the natural dam. Rock Creek Campground, just upstream from the slide, was flooded in a matter of hours.

The rising water threatened to flood downstream communities. In the first panicked hours some important questions arose. Would the loose rock dam hold when the lake filled up completely? Would water flowing over the top of the slide rapidly erode a channel and cause a flood downstream? Would water backed up by the slide reach Hebgen Dam and weaken it, posing still another flood threat?

The U.S. Army Corps of Engineers dug a temporary spillway with heavy equipment. They used the boulders from the slide to line the channel.

Originally 190 feet deep, Earthquake Lake has been slowly subsiding as the Madison River gradually erodes through the slide. In a century or two, Earthquake Lake will not exist and the Madison River Canyon will appear more like it did before the earthquake.

Many effects of the earthquake-triggered the landslide of 1959 are becoming less apparent with time.

We arrived “back at camp” feeling like we had ridden horses all day.


6 responses to “Day 15-18 Yellowstone National Park PART II

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  2. Pingback: Tweets that mention Day 15-18 Yellowstone National Park PART II « Adventures of Carol and Bill --

  3. gonna send this to my mom

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