Morning Glory Pool is a geothermal feature located in the Upper Geyser Basin of Yellowstone National Park, Wyoming, United States. It is classified as a hot spring and is renowned for its vivid blue‑green coloration, which results from microbial mats and mineral deposits interacting with the pool’s thermal waters.
Geological characteristics
- Formation: The pool occupies a depression formed by volcanic activity and is fed by underground geothermal vents.
- Temperature: Measured surface temperatures typically range from 68 °C to 71 °C (154 °F to 160 °F), although temperature can vary seasonally and after seismic events.
- Coloration: The striking turquoise hue is produced by thermophilic microorganisms (primarily cyanobacteria) that thrive at high temperatures, along with the scattering of sunlight by fine silica particles suspended in the water. Changes in microbial populations or mineral precipitation can alter the pool’s color.
Historical context
- The name “Morning Glory” was applied by early park visitors in the late 19th century, referencing the pool’s bright, flower‑like appearance at sunrise.
- The pool was documented by the U.S. Geological Survey and the National Park Service in early park maps and scientific reports.
Human impact and conservation
- In 1995, a visitor inadvertently threw a rock into the pool, causing a temporary disruption of the thermal feeding system and a noticeable shift in coloration. The incident highlighted the pool’s sensitivity to physical disturbance.
- The National Park Service now enforces strict protective measures, including boardwalks and signage, to prevent direct contact and preserve the pool’s natural state.
Tourism
Morning Glory Pool is accessible via the boardwalk of the Upper Geyser Basin trail network, drawing considerable visitor interest due to its visual prominence among Yellowstone’s many hydrothermal features. Photographic documentation is common, but visitors are advised to remain on designated pathways to avoid ecological disturbance.
