25 June 2016 – So sunrise is like at 5:30. The poopy dogs are ready to go out at about that time. That means no sleeping in. The temperature this morning is 42F with a high forecasted at 80F at 40% humidity. Lovin’ that being from south central Texas. Today we visit West Thumb and Old Faithful, so we will be walking in the open sun most of the day. Put on the sunscreen and wear a hat ‘cause it’s high & dry up here.
About 21 miles south of Fishing Bridge lies the West Thumb Geyser Basin. It sits along the edge of the West Thumb of Yellowstone Lake. The name comes from a visual of your hand. Hold up your right hand palm facing outward. Holding your fingers together tilting them slightly to the right. Now stretch your thumb as far down as you can and that, my friend is a rough image of the Lake and its West Thumb.
Yellowstone Lake is within a massive caldera that collapsed after a violent volcanic eruption around 640,000 years ago. A second smaller eruption about 174,000 years ago formed the caldera known as West Thumb. So, it is actually a caldera within a caldera. The basin contains many hydrothermal vents and hot springs just offshore.
A boardwalk allows visitors to stroll amongst the onshore features, complete with the sulfurous odor emanating from the vents. Elk find it warm and inviting on cool mornings. Two were grazing during our visit. After a leisurely stroll around the boardwalk, and honoring the requests of a few Japanese tourists for photos, we head to Old Faithful.
The parking lot at Old Faithful is huge. We chose a place closer to the lodge that gave us a direct walk to the benches around the famous geyser. The NPS has Old Faithful’s eruptions timed at every 45 minutes within a 10 minute window. We were about 30 minutes from the next eruption, so we sat on a bench and waited. Sure enough at about the posted time, there she blew. Never having experienced this, what a spectacular sight! Everyone was rightfully awestruck.
We walked around the boardwalk to see the world’s largest array of active geysers. The area sits atop an active volcano where magma is as close as 3 – 8 miles below ground. As rain and snow seep into the ground the water becomes super-heated. At a critical point, the steam finds its way to the top pushing the water up and out of the geyser. We were actually caught in the spray of Old Faithful as we walked along the path. Fortunately with the cool weather and our proximity from the event, the water was not hot. Nice soaking from an iconic feature of Yellowstone.
There are plenty of other geothermic features in the Upper Basin. Besides geysers, one finds hot springs that feed into the Firehole River, fumaroles with little water to spew vent steam, and mudpots where hydrogen sulfide helps reduce the surrounding rock into a thick clay soup with a sulfurous odor.
Only six of the geysers are somewhat predictable, most are not. Old Faithful erupts more frequently than others spewing some 3700 – 8400 gallons of boiling water to a height of 106 – 184 feet.