Travel Reference
In-Depth Information
with its many vents; and
Old Tardy.
Last encountered before you rejoin the main walk is del-
icately colored
Belgian Spring,
where a tragedy occurred in 1929: a newspaper editor from
Belgium died after falling into this pool.
Turn right to rejoin the straight part of the boardwalk. We'll pick up the missed section
of the main walkway on the way back, labeled
(B)
on the Upper Geyser Basin map and de-
scribed on
page 97
.
You're approaching what many geyser lovers consider the most exciting geyser of all to
watch,
Grand Geyser.
Before reaching Grand you'll come to some small geysers connected to
it underground, including
Rift Geyser,
which seems like just an innocuous group of cracks,
but, when active, can influence Grand's eruptions;
Triplet Geysers,
of which only
West
Triplet
erupts with any frequency now; and
Percolator Geyser,
which
does
sound like coffee
percolating. Percolator Geyser has upon occasion been known to play for two hours or so be-
fore Grand's eruption. West Triplet is located closest to the boardwalk, and Percolator is in the
middle of a direct line from West Triplet to Grand.
How Does a Geyser Work?
After you've seen some geysers, you'll probably want to know how a geyser works. The ba-
sic requirements are a water source, a heat source, and some rather complicated plumbing.
The Sources and the Plumbing
Snowmelt and rainfall provide the water by soaking into the ground locally and from the
surrounding mountain ranges. The water flows deep into the geyser basin as groundwater,
reaching hundreds of yards (meters) below ground level, as shown in the diagram.
The still-hot volcanic rocks found below Yellowstone's geyser basins provide the source
for heating the water. The rocks continuously receive heat because there is magma a few
miles below the surface.
The plumbing that all geysers have consists of a vent connected to a narrow crack that
goes down into the hot rocks, widening into chambers and narrowing into channels as it
goes and intersecting a multitude of tiny cracks and pores that feed water into the geyser.
What Happens to the Water
Let's follow the cycle at the point just after an eruption has ended.
1. The vent and crack have been largely emptied of water. A small part of the water that
shot up into the air falls back into the geyser vent and drains down the crack. Of course,
this water is much cooler than when it shot out.
