How Did The Grand Prismatic Spring Form?

The Grand Prismatic Spring is a vibrantly colored hot spring that genuinely looks like something out of a science fiction movie!

You probably know this is a famous hot spring, but have you ever considered how this incredible natural phenomenon came to be? How did the Grand Prismatic Spring form?

The Grand Prismatic Spring formed when hot water, which the Earth’s core had warmed, bubbled up through cracks in the Earth’s surface to form a pool on the surface. The colors happen due to bacteria living along the spring’s edge.

Hot springs are incredible features, but the Grand Prismatic is something extra special, and you are going to find out why!

This article is going to help you get to know the Grand Prismatic Spring a bit better and tell you exactly how it formed to create this stunning spectacle.

Hot Spring Hunt Fact: The Grand Prismatic Spring is the largest hot spring in the United States.

What is the Grand Prismatic Spring?

Before we get into how this hot spring formed, I want to introduce you to this beautiful natural feature.

Let’s look at some of the specifics.

 Grand Prismatic Spring
LocationWyoming, United States
Discharge560 gallons per minute
Diameter300 feet
Depth160 feet
Temperature160 F

The Grand Prismatic Spring is a stunning feature in Yellowstone National Park, the United State’s first official national park. If you are planning a trip to Yellowstone, then this has to be at the very top of your list!

First unofficially recorded by colloquial fur trappers in 1839, this spring is very large and sits on a bed of rhyolitic rock with high silica content. It was noted down as a ‘boiling lake,’ and it was officially documented by the Hayden Expedition in 1871.

Its name comes from the stunning colors of the hot spring that form a rainbow across the surface. But don’t worry; we’ll be getting into why this happens later.

Due to the intense heat, this spring cannot accommodate life outside of very specialized bacteria.

As a visitor, the Grand Prismatic Spring is viewed from an elevated walkway that runs along one edge of the spring. This lets you get closer to its beauty without being at risk of coming into contact with the hot water.

How Did the Grand Prismatic Spring Form?

The Grand Prismatic Spring is a hydrothermal spring that is formed when water that has been heated by subsurface magma and bubbled up through cracks in the earth’s surface. The colors are created by specialized bacteria that live on the edge of the spring.

Yellowstone is known for its multiple hydrothermal features, and this is one of them! What sets the springs apart from the geysers is that there are no obstructions on the surface that make the water come out in a violent manner, like Old Faithful.

Instead, a non-stop cycle is created by the hot water rising to the surface, spreading, cooling, and dropping again before the cycle starts again.

Now I know what you’re thinking, where do the colors come in? Well, that’s what makes the Grand Prismatic Spring so unique!

As you can see from the pictures, the spring features a rainbow of colors across the white light spectrum. It starts with a deep blue at the center, where the water bubbles up from. This is the most sterile area of the spring, and it is blue for the same reason that any body of water appears blue.

The stunning spectrum of colors is formed due to different bacteria living along the edge of the spring.

As the water rises to the surface and spreads outwards, it will cool to form concentric circles of water at various temperatures. Within these circles live several bacteria that thrive at different temperatures. This includes cyanobacteria that require photosynthesis to survive.

These bacteria live by balancing their photosynthetic pigments, which reflect different wavelengths of light. This creates bands of color that change in a gradient according to the temperature of the water to create this incredible rainbow spectrum across the surface.

These colors will vary depending on the season, weather, and water temperature, which means that the spring’s appearance is ever-changing.

Hot Spring Hunt Fact: The Grand Prismatic Spring is the third largest hot spring in the world, behind Frying Pan Lake in New Zealand and Boiling Lake in Dominica.

Frequently Asked Questions

Is the Grand Prismatic Spring Old Faithful?

Many get this confused, but, in fact, these are two separate features.

Old Faithful is located 7.5 miles south of the Grand Prismatic Spring and is a geyser rather than a hot spring.

What happens if you swim in the Grand Prismatic Spring?

It is actually illegal to swim in the Grand Prismatic Spring for a very good reason.

Due to the heat and mineral content, swimming in the spring could cause major burns and even death.

Does the Grand Prismatic Spring smell?

Since there are high levels of sulfuric acid and hydrogen sulfide gas in geothermal springs like the Grand Prismatic Spring, it will have a slight sulfurous odor.


Looking at a beauty like the Grand Prismatic Spring makes you take a step back to marvel at how incredible nature really is.

This amazing spring was formed when hot water from the Earth’s core bubbled up through fractures in the earth’s surface to form a pool. The colors come down to the activity of bacteria around the spring.

I hope that learning this has inspired you to add Yellowstone and the amazing Grand Prismatic Spring to your travel list!

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