Get to know Morning Glory Pool

Morning Glory Pool is one of the most famous hot springs in Yellowstone. In this post, you’ll learn more about this beautiful and interesting pool.

THE BASICS

• Not known to naturally erupt.
• Plumbed to a depth of 27.5 feet.
• Located about a mile’s walk from Old Faithful.
• It is no longer the blue many people expect, but is, instead, green.

WHERE IT’S LOCATED

Morning Glory Pool is located about a mile away from Old Faithful. To reach it, walk along the paved walking/bike trail, continuing along this all the way to end where the boardwalk takes you straight to it.

MORNING GLORY’S HISTORY

This spring is named for its shape that looks very much like the trumpet of the Morning Glory flower. When named, the color also matched the blue of the flower as well. However, its story illustrates the delicate nature of thermal features.

In the earliest days of the park, Morning Glory Pool reportedly had a scalloped edge to it that was 6-10 inches wide and 2-5 inches high. This quickly disappeared because visitors wished to take a piece home with them. That practice is now thankfully not allowed. However, the delicate edging has not rebuilt itself as certainly, those early visitors assumed it would.

The walking/bike path used to be the old road that leads visitors into the Upper Geyser Basin and to Old Faithful. This pool was a favorite to stop at and admire. But also in those days, the delicate nature of the thermal features was not understood or appreciated. Due to that, much trash was tossed in. This trash could have been part or all of the reason for the change in color to the green we often see today. Clogging up the vent has the potential of irreparably damaging hot springs. While attempts have been made to remove trash from the vent, the blue color has not returned.

WHAT MAKES THE DIFFERENT COLORS IN THE POOLS?

Blue is the natural color of water no matter where you see it. The shade of blue is affected by depth and the color of the surface the water lies upon. When the temperature of a hot spring is extremely hot, the color is navy blue. No microbes grow in this high-temperature water. Even when it’s a lighter clear blue, no microbes grow. But when it cools a bit more (“cool” being a relative term – still hot enough to scald in seconds), yellow microbes start to grow on the walls of the vents. Blue and yellow make green. When the water “cools” more, you get dark orange microbes. Mix dark orange with blue and you get an inky green.

A RECENT HEATING UP

In 2018, Morning Glory Pool did heat up more than it has in many years with a large section of the vent hot enough to turn a lovely shade of blue. Interestingly, it heated first from the side and then the heat moved down the vent. This likely means there’s another source of hot water next to it that remains below the surface. You can see the summary photos from 2018 in this blog post (Morning Glory Summary 2018).