Mammoth Hot Springs, Yellowstone National Park, Wyoming 6 July 2006

    Yellowstone sits on the huge caldera of an ancient volcano.  The geysers and hot springs that dominate the western half of the  Park are vents

for the constant pressure building underground.  The calcite and sulphur shapes of Mammoth Hot springs are the most impressive. [25 photos]

A long-cooled vent left a 30-foot tall tower at Mammoth Hot Springs (MHS).

Rolling cascades lead to bright white sulfur terraces at the main formations at Mammoth Hot Springs.

The face of the cascades. Hot water, laden with sufur and calcite, leave deposits as they pour down and evaporate.

When the water passes or evaporates, white terraces form

The cascading water creates beautiful patterns on the calcite, which has been smothed by constant erosion over the centuries.

Steam rises as the hot cascading water reaches the cooled water in the terraces.

In 2004, the Boston Red Sox came back from an 0-3 deficit to beat the Yankees in four straight en route to their first World Series title in 86 years.

But that has nothing to do with what you're looking at. Just checking to see if you were paying attention.

Were you? Did you even read the caption? I know the photos in this batch are similar, but take the time to look at them closely.

This was a view from a platform on top of Mammoth Hot Springs. I bet this place is amazing in the snow-mantled winter.

With ice and snow all around, this water still would run very hot, and create quite a steam show.

What was once a small gurgle of hot water, grew to a 15-foot-tall mound of calcite deposits.

The hot water still flows steadily across its surface and uniformly down the sides...

... smoothing the slopes and deepening the hues.

Roaring Mountain, 20 miles to the south, was another creation of vents and the deposits they leave behind.

In its prime, Roaring Mountain could be heard for miles -- hence the name.

Norris Geyser Basin, on the west half of Yellowstone NP

Norris Geyser Basin

Norris Geyser Basin

Norris Geyser Basin

Norris Geyser Basin

Norris Geyser Basin

Norris Geyser Basin

Norris Geyser Basin

An ugly blob, venting hot water, along Winter Creek.