West Thumb

Between Fishing Bridge and Old Faithful is a large circular bay of Yellowstone Lake. A powerful volcanic eruption approximately 174,000 years ago caused the earth's crust to collapse, creating the West Thumb caldera. The depression later filled with water to become this large bay of Yellowstone Lake. The West Thumb caldera lies within an even greater caldera, the Yellowstone Caldera, which is one of the world's largest. It resulted from a massive eruption roughly 640,000 years ago.

Our first stop was to hike up a hill behind the West Thumb Geyser Basin. On the way up the hill four elk came charging across the trail and up over a ridge into the forest. We were surprised to see the dust because everything is so wet from the winter snow melt.

Lunch spot at the top of the hill and a nice bench provided by the park.

As we ate our lunch we watched an approaching thunder storm.

Just beyond the bench you might be able to see a short guard rail.

It is there to protect hikers from the various steaming vents  and small pockets of boiling water that surround the area at the top.

We got back to the parking area, and the car, just as the rain arrived. We decided to wait out the rain before we ventured out on the boardwalk through the thermal features of West Thumb's Geyser Basin. The sun came out and that makes a big difference in the colors of the pools. this one is called Bluebell Pool.

there are lots of these yellow flowers around the thermals. They must like the warmth and the moisture.

Down on the lakeshore, the boardwalk took us by Lakeshore Geyser. The two vents are underwater now but later in the summer the geyser is exposed above water and may erupt a couple of feet.

This beauty is call Black Pool. At one time it really was black . Lower water temperature allowed thick mats of dark green and brown thermophiles (heat-loving microorganisms) to grow in the pool, causing it to appear black. The water temperature rose during the summer of 1991, killing the organisms. Notice the delicate edge all around the pool.(Have you clicked on the pictures to enlarge them?)

Abyss Pool

View across the central basin to Yellowstone Lake and the mountains beyond.

Twin Geysers - one geyser with two vents. Its last know eruption was in 1999 when both vents erupted as high as 75 feet. 

Thumb Paint Pots and...

mud volcanoes.

The storm has moved on and Yellowstone Lake, with the Abaroka Mountain Range look beautiful from West Thumb.

We often see groups of these religious travelers, especially when we visit national parks, both in the States and in Canada. We don't know the name of the religious group - maybe Mennonites?

Today's hike:

Length - 2.8 miles

Duration - 1 hour, 53 minutes (including lunch)

Elevation gain - 337 feet