Final answer:
The vibrant colors of the Grand Canyon of Yellowstone are due to the geothermal features, rich mineral content, erosion revealing the colors, iron oxide, sulfur, and thermophilic bacteria such as cyanobacteria.
Step-by-step explanation:
The red, brown, and yellow colors observed on the walls of the Grand Canyon of Yellowstone are attributed to the geothermal features and the rich mineral composition of the rocks. Erosion over centuries has revealed the dynamic red and yellow colors in the stratified cliffs.
The colors in the canyon can also be attributed to the iron oxide present, which gives the rocks their reddish hue, while the varying shades of yellow are owing to the sulfur content. Furthermore, the presence of thermophilic bacteria, such as cyanobacteria, adds to the varied pigmentation seen in the geothermal areas. For instance, as seen in Figure 13.2 of Yellowstone National Park, cyanobacteria exhibit green colors where the water is cooler and become more intense as the cell density increases.