Hotsprings, A Steamy Subject ...
Where does the spring water come from?
Most of the rain and snow that falls on the slopes of a mountain
ends up in rivers and streams. Some of it, however, filters
down through the cracks and pores in the mountain rock, pulled
by gravity to a depth of three kilometres below the surface.
It is this water which later bubbles to the surface in our
Canadian hot springs.
Why is it warm?
As it seeps into the ground, the water becomes hotter and
hotter — heated by radioactive decay in the earth's
core. When the water boils, pressure forces it upward, just
like the water in a coffee percolator. The speed at which
the water rises, and the degree to which it mixes with cold
ground water, causes the temperature to fluctuate.
Where does the odor come from?
As the water heats up, it dissolves minerals in the surrounding
rock. When these dissolved minerals break down, they release
hydrogen sulphide gas, which smells like rotten eggs. Pyrite
and gypsum are two common sulphur-bearing minerals dissolved
in the Banff and Miette hot springs. The water at Radium Hot
Springs is odorless because of the type of rock in that area.
What is tufa? (pronounced too-fa)
As the hot springs water bubbles from its underground channel,
it begins to drop the load of minerals it gained on its journey
through the earth. One of these minerals, calcium carbonate,
hardens into a porous grey/brown rock called tufa. The entire
hillside around each hotspring is composed of tufa.