Sunday, September 16, 2012

Geysers in Yellowstone National Park, WY (Part 1)

I was originally not excited to come to this park.  We typically stay away from heavily toured areas, and Yellowstone National Park is a very busy park.  It receives millions of visitors each summer, and the season here is short, from June to late September.  But, it's a bucket list destination, so here we are.  And what an overwhelming surprise.  The campground is small, but we manage to squeeze our trailer into our site, and I mean squeeze!  Like in Ontario Provincial Parks, these campgrounds were built in the 1960s before big RVs were really heard of, so even though the pull-through sites are paved, we can barely fit into most spots, and there are several hundred in the many campgrounds in the park.  Sure, we could stay in the expensive RV park, but expensive and RV park isn't our thing.  Anyway, the attractions...

Within Yellowstone NP, there are geysers, hot springs, fumaroles and mud pots.  What makes them different?  Ok, so here's the geology lesson.  Yellowstone's heart is an ancient caldera - a collapsed volcano cone or basin.  The volcanoes here erupted 2 million, 1.3 million and 640,000 years ago.  But the hot magma (molten rock) still powers the formations found in Yellowstone.  Iceland and New Zealand also have geysers, but nowhere on earth is the concentration of geysers as high as in Yellowstone.  A geyser happens when underground water that has seeped through cracks in the rock and earth is heated by magma which here is as close as 1 mile underground or may be 3-8 miles deep.  The water rises as it heats, but reaches a constriction point between the heat source and the earth's surface and can't easily escape.  Therefore, with the weight of the overlying water, the pressure increases, just like in a pressure cooker.  Then suddenly as the water passes the constriction point, its pressure drops causing the boiling temperature to also drop and the water therefore instantly turns to expanding steam which causes high pressure.  The steam forces the water on top of it to erupt into the sky.  The water escaping the vent is hotter than boiling temperature (which here at this elevation is 199F).  Please step away from the geyser!

A hot spring is the same as a geyser, but there is no constriction point, so the heated water simply circulates to the surface of the pool where it may run-off, evaporate or cool and recirculate.  Fumaroles vent only steam.  Their underground systems are so hot and they contain so little water of their own, that as rain or melting snow seeps into the cracks it is instantly converted to steam by the intense heat.  Mudpots are highly acidic features.  Microorganisms living in the mud pots convert hydrogen sulfide (a very smelly gas) into sulfuric acid which dissolves rock into clay.  With the heat from the magma below, the clay bubbles.  These mud pots may look like muddy boiling water or thick bubbling clay.

Old Faithful erupting
The park is dissected into main areas.  We spend an entire day at the Old Faithful area, watching Old Faithful erupt (every 95 minutes give or take 10 minutes, and we see it three times today) and hiking the trail to the many other geysers, hot springs and pools in this section of the park.  It takes us many hours to walk the 3 mile trail up to the Morning Glory Pool because we often just park our butts on the bench and wait for the next imminent eruption, some of which are very predictable within an hour or two.  This pays off twice as we get to witness Grand Geyser and Riverside Geyser erupt.  Grand Geyser is spectacular!  First the pool slowly fills and overflows its ledges.  Then Turban Geyser right behind it spouts a few feet of water and steam, then suddently Grand takes off in an explosion resembling a fireworks display!  Boom, boom, boom - again and again.  It erupts for about 10 minutes, sending boiling water and steam almost 200 feet into the air.  Turban Geyser behind it throws out its contents about 20-30 feet high, and then Vent Geyser beside that vents steam on an angle to the left.  It ends all at once, and the crowd (about 50 or 60 of us) bursts into a round of applause.  we can't help it - what a spectacular show.  Then, as if to thrill us with an encore, Grand Geyser erupts again, with even more volume of water and steam as if to say "Oh yeah?  That was nothing.  Watch this!"  The encore lasts only a few minutes and then abruptly the large pool drains as if a higher power has pulled the plug.  I am breathless.

Grand Geyser erupting, with little Vent Geyser on the left
Further along the trail, we wait for Riverside Geyser to erupt (the probable eruption times are noted on a board beaside each geyser - thank you Rangers!).  This geyser is a pool of water suspended half-way up the bank of the Firehole River.  The pool fills and overflows into the river, then it starts bubbling, and within one to two hours of these events erupts 75 feet into the air - for over 20 minutes!  Towards the end of the show, there is more steam than water and a beautiful rainbow appears.  What a thrill, and worth the wait!  The other springs and geysers in this area are all unique; some predictable as to when they will erupt and others not.
Brad & Marilyn at the Morning Glory Pool
Riverside Geyser, on the Firehole River
In the West Thumb area near our campground, the pools are beside Yellowstone Lake.  None of these geysers have erupted in recent years, although some as recently as 2005.  I don't think we'll wait to see any of these spout.  Yellowstone Lake, the largest lake at a high elevation in North America, is a frigid 45F in the summer, even with boiling water pouring into it from these pools, and yes, many of the springs are constantly flowing and are 160F or higher.  Some of the pools, like Black Pool and Abyss Pool are a beautiful light blue colour, reminding us of the springs we visited last spring in Florida.  However, these pools are over 160F, so no snorkeling here!

Black Pool and its runoff which is coloured by micro-organisms

Abyss Pool overlooking Yellowstone Lake
I am now anxious to continue our adventures in Yellowstone.

1 comment:

  1. I love your description.... Wish I was there too!