Can you describe what you see in this picture?
At first glance, it may look like trees lined up against a vibrant sky. But hold on, is that a reflection?
This photo shows off a delightful phenomenon—rock flour—responsible for the color of many of Glacier's lakes and streams.
At first glance, it may look like trees lined up against a vibrant sky. But hold on, is that a reflection?
This photo shows off a delightful phenomenon—rock flour—responsible for the color of many of Glacier's lakes and streams.
What is rock flour?
To answer that, you have to start with Glaciers. Glaciers are distinguished from other bodies of ice by the fact that they move. As they move, they grind and scrape the ground beneath them, pulverizing rock into particles so small they resemble flour.
To answer that, you have to start with Glaciers. Glaciers are distinguished from other bodies of ice by the fact that they move. As they move, they grind and scrape the ground beneath them, pulverizing rock into particles so small they resemble flour.
When this flour-like substance finds its way to water, it gets suspended throughout and is very slow to sink.
How does rock flour turn a lake blue?
While rock flour is a terrible gluten-free alternative when baking, it excels at reflecting turquoise and blue light.
How does rock flour turn a lake blue?
While rock flour is a terrible gluten-free alternative when baking, it excels at reflecting turquoise and blue light.
When sunlight hits the surface of a glacial lake, water itself absorbs long wavelengths of light (red, yellow, orange, etc.). Glacial flour, on the other hand, absorbs short wavelengths like indigo and purple. The remaining blues/greens are scattered and reflected for all to see.
Why then are some lakes different shades of blue?
The color of a glacial lake/stream depends on a few things. Generally, you can guess how close a lake is to an active glacier by its coloration; the more rock flour a lake contains, the brighter the color!
The color of a glacial lake/stream depends on a few things. Generally, you can guess how close a lake is to an active glacier by its coloration; the more rock flour a lake contains, the brighter the color!
As the sun moves throughout the sky, these colors take on different tones. The same lake may also look different from shore than it does from the nearby trail that climbs over 1000 feet.
(Bonus points if you can guess which lake this is!)
(Bonus points if you can guess which lake this is!)
For up to date information on what's open in the park, visit our Status Update Page here: nps.gov/glac/planyourv…
This photo of trees reflected in a blue lake was taken on the traditional land of the Amskapi Piikuni, Kootenai, Selis, and Qlispe People in 2020 📍
This photo of trees reflected in a blue lake was taken on the traditional land of the Amskapi Piikuni, Kootenai, Selis, and Qlispe People in 2020 📍
