After checking into the campground, which would be my “base” for two nights, I drove the southern loop through the park. My first stop was the West Thumb Geyser Basin, which overlooks Yellowstone Lake, the largest lake at high elevation (7,733 feet) in North America – it encompasses 131.7 square miles, is 14 miles wide and 20 miles long, with an average depth of 140 feet. In other words, it is HUGE! And beautiful, with the Absaroka mountain range on its eastern side.
The volcanic caldera at West Thumb contains many geothermal features including pools, springs, geysers, and paint pots. Above is a view of the central portion, which sits above the lake. The geysers, however, are currently in a dormant stage, thus no eruptions were seen.
The Abyss Pool is one of the deeper hot springs in the park, descending to a depth of 53 feet.
The trail guide states that Black Pool was, at one time, actually black. Cooler water temperatures 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.
Walking alongside the pool on the boardwalk you could feel the heat from the hot water. At times, the steam rising from the pool was so thick you couldn't see the other side!
The water appears to be turquoise but it was so clear you could easily see portions of the bottom. There were several deeper areas – the “black holes” where the bottom could not be seen.
Interesting formations line the sides of the pool.
Constantly in a state of change, new features appear every day.
Hot water from Black Pool and other features in the area flows into Yellowstone Lake. The color variations are caused by those little thermophiles – microorganisms that thrive in the hot water.
Along the shore of Yellowstone Lake is this feature, called Big Cone. It's difficult to tell from the angle of the photo, but the cone rises about 12 inches above the outer surface.
Boiling hot water bubbles up in the Big Cone.
Further along the path and completely surrounded by water is the “Fishing Cone” so called because Mountain Men told of catching a trout in the lake, swinging the pole around, dipping the catch in the boiling pool, and cooking the fish without even taking it off the line! Sometimes in spring and early summer the Fishing Cone is underwater due to the rising lake waters from snow melt.