Colorful Rocks

Lake McDonald is a popular spot for Glacier National Park visitors to view our "fruity pebble" colorful rocks along the shore. Anthony tells us more about how these rocks get their color. The answer might surprise you!

Hey Anthony, what’s with these colorful rocks we have here? It’s a really good question, Garrett. These rocks– We’re standing on the shore of Lake McDonald here near West Glacier– And these rocks were formed with different levels of oxygen in the atmosphere. So, if you look at these kind of bluish greenish rocks, these were formed without the presence of oxygen in our atmosphere. You look at these red rocks and you think about rust, the color of rust, and that’s an oxygenation process. These Red Rocks were formed when oxygen was here on the planet, kind of created that redish color. Super cool! I won’t take that information for granite. And of course, we’re gonna remember to put these back exactly where we found them.