#black opal pool

Yellowstone National Park, WY (No. 23)

Yellowstone is at the northeastern end of the Snake River Plain, a great bow-shaped arc through the mountains that extends roughly 400 miles (640 km) from the park to the Idaho-Oregon border.

The volcanism of Yellowstone is believed to be linked to the somewhat older volcanism of the Snake River Plain. Yellowstone is thus the active part of a hotspot that has moved northeast over time. The origin of this hotspot volcanism is disputed. One theory holds that a mantle plume has caused the Yellowstone hotspot to migrate northeast, while another theory explains migrating hotspot volcanism as the result of the fragmentation and dynamics of the subducted Farallon Plate in Earth's interior.

The Yellowstone Caldera is the largest volcanic system in North America, and worldwide it is only rivaled by the Lake Toba Caldera on Sumatra. It has been termed a "supervolcano" because the caldera was formed by exceptionally large explosive eruptions. The magma chamber that lies under Yellowstone is estimated to be a single connected chamber, about 37 miles (60 km) long, 18 miles (29 km) wide, and 3 to 7 miles (4.8 to 11.3 km) deep. The current caldera was created by a cataclysmic eruption that occurred 640,000 years ago, which released more than 240 cu mi (1,000 km3) of ash, rock and pyroclastic materials.This eruption was more than 1,000 times larger than the 1980 eruption of Mount St. Helens. It produced a caldera nearly 5⁄8 mi (1.0 km) deep and 45 by 28 miles (72 by 45 km) in area and deposited the Lava Creek Tuff, a welded tuff geologic formation. The most violent known eruption, which occurred 2.1 million years ago, ejected 588 cu mi (2,450 km3) of volcanic material and created the rock formation known as the Huckleberry Ridge Tuff and the Island Park Caldera. A smaller eruption ejected 67 cu mi (280 km3) of material 1.3 million years ago, forming the Henry's Fork Caldera and depositing the Mesa Falls Tuff.

Yellowstone National Park, WY (No. 22)

As the name suggests, Wall Pool is a pool with a wall and an overhanging shelf of sinter to the west. Wall Pool is related to Black Opal Pool and Black Diamond Pool as a hydrothermal explosion crater. Wall Pool was created by one of the steam explosions in the early 1900s. Wall Pool exploded again in 2005, but activity has continued to decrease. It actively boils and the edges of the pool and surrounding runoff contain orange and yellow thermophiles.

Wall Pool has an average temperate of 190.5°F (88°C), an average pH of 7.9, and an average conductivity of 1833 uS/cm.

Yellowstone National Park, WY (No. 21)

Black Diamond Pool is a large murky blue pool with water flowing into other pools nearby. Soft sinter and sparse vegetation surrounds the area of the pool. Outflow from the pool forms braided channels of orange and green thermophiles. These large pools formed from hydrothermal explosions. While not all historic explosions are known, Black Diamond Pool erupted black murky water after an earthquake in July 2006, with several explosive eruptions in the following days. Eruptions continue to be infrequent since, with the last eruption observed in 2016.

Black Diamond Pool has an average temperate of 148.5°F (64.7°C), an average pH of 8.2, and an average conductivity of 2092 uS/cm.