Final answer:
The oldest geyser in Yellowstone National Park, between 5,000 to 15,000 years old, is the Castle Geyser, known for its large sinter cone.
Step-by-step explanation:
The geyser referred to in the question, estimated to be between 5,000 to 15,000 years old, is the Castle Geyser in Yellowstone National Park. Castle Geyser is known for its large cone made of sinter, which took thousands of years to form.
This impressive feature, indicating its age, helps it stand out among the other geysers in the area like Old Faithful and Steamboat. Yellowstone National Park is not only famous for its geysers but also for the Grand Prismatic Spring, which showcases a rich palette of colors due to microbial life around its edges, and the iconic Grand Canyon of the Yellowstone, immortalized in the painting by Thomas Moran which captures the park's staggering natural beauty.
Yellowstone's various hydrothermal features, such as hot springs and geysers, offer insight into ancient life forms and the planet's geological history. These natural phenomena are demonstrations of thermodynamic principles at work, with water in the geyser's underground channels being heated by magma and resulting in spectacular eruptions.