Travel Reference
In-Depth Information
steam clears away, you can see greenish yellow crusts of sulfur and red deposits of iron on the
cavern roof. Stretching away from this point are two very large hot springs called the
Gray
Lakes,
whose waters are said to be in constant motion, caused by boiling springs on the bot-
tom.
West of the Gray Lakes, not visible from the walkway but partially visible from the high-
way, are the
Hydrophane Springs,
whose color is reflected in its name and its steam. Hydro-
phane is a type of opal that becomes translucent when immersed in water.
Phillips Caldron,
usually a pool of opaque water, honors Charles Phillips, a park ranger
who was fascinated by geysers. Lamentably, while stationed for the winter at Old Faithful in
1927, he mistook poisonous water hemlock growing in warm thermal runoff for edible wild
parsnip and died within a few hours of eating it.
West of the path, the
Muddy Sneaker Complex
(including one small geyser) got its name
from park geologist Rick Hutchinson in 1971. It was originally a violent mud pot that sprang
up suddenly in the trail. “Anybody who would walk in it or below it would get their shoes or
sneakers muddy,” according to Hutchinson. The path has since been moved uphill.
Very close to the path is
Blue Mud Steam Vent,
a deep round pot of vigorously boiling
muddy water (in 2012), with edges lined with blue-gray mud.
Blue Mud Steam Vent displays unusually colored mud and water.
Yellow Funnel Spring
near the boardwalk corner deserves its name only part of the time.
Sometimes you can't see the yellow-stained funnel for the opaque green, blue, or muddy wa-
ter; sometimes it's merely a steam vent.
Son of Green Dragon
north of Yellow Funnel some-
times acts as a geyser.
This area of Back Basin, from Yellow Funnel Spring to Pearl Geyser, became so hot in July
2003, with soil temperatures near boiling and new fumaroles everywhere, that park officials
closed the former straight boardwalk. In 2004 a new raised boardwalk loop was built to bypass
