While New Zealand and Iceland are noted for their hot springs and geysers, Yellowstone claims to have more of them--10,000 thermal features of which over 300 are geysers. They are scattered all through the park but usually can be seen in groupings around areas where the hot water has found its way to the surface. The largest areas are the Norris Geyser Basin, the Mammoth Hot Springs and of course the Geyser Basin where Old Faithful can be found.
When we first met with a ranger to get an idea of how to get around the park and what to see, the ranger tapped Bob's finger and said, "This is not a thermometer. Do not test to see how hot the water is." And yet, every so often you would see someone do it. Some of the thermal features can actually get hotter than the boiling point.
Hot springs are the most common. They are pools of water that give off a lot of steam especially on those days that the temperature dropped. The hot water rises to the surface gets cooled a bit sinks, reheats and rises again.
|Terraced Mammoth Hot Springs|
Fumeroles or steam vents are the hottest features. They often sound like a tea kettle steaming only with out the whistle. They hiss and throw out a lot of steam.
Travertine Terraces are fascinating--especially the huge one at Mammoth Spring. The terraced deposits are from water rising through the limestone carrying large amounts of calcium carbonate. When it is deposited, it forms travertine, the chalky substance you see in the picture. It all looks like something a landscaper may have created for a focal point with a fountain in the yard of a mansion.
Geysers are hot springs with smaller escape hatches through which the hot water escapes. The heat builds up deep in the earth causing the water to boil but because of the weight of the water above the hot water, pressure builds. Eventually the bubbles in the hot water cause the water above it to push out of the opening in the earth causing an explosion of water as if someone had turned on a fireman's hose and aimed it into the air.
We waited until our third day in the park to go to Old Faithful. The first two days were cloudy and rainy and sometimes snowy. Old Faithful was one of the must-sees for me so I wanted a good day. Unfortunately it was clouded over every time we saw it go off. They estimate it will erupt every 60 to 90 minutes. Each time it does, the rangers calculate the next predicted time with a give or take of ten minutes. Old Faithful was within two minutes either side of the predicted time each time we watched it.
Each thermal feature has its own palette of colors that are amazing. There are actually microorganisms that survive quite nicely in the hot water and lend their colors to the water and the deposits and rocks around the features.
There are lots of warnings everywhere about staying on the boardwalks and not stepping onto the areas surrounding the features mainly because they could be very hot or fragile. In one area we found lots of people had lost some very nice hats in a few gusts of wind and had to leave them behind. It explained the ranger we saw though with a long pole that had a claw on the end of it.
Tip of the day: Hold on to your hat!