Tardy Geyser is a shallow, blue pool with rims of geyserite around the small vent at the middle of the pool. Outside of the geyserite rim, shallow water collects and orange thermophiles grow along the runoff channels. Tardy Geyser is part of the Sawmill Complex and likely gained its name from its record of activity right after a Sawmill Geyser eruption.

Tardy Geyser has an average temperate of 173.1°F (78.4°C), an average pH of 8.2, and an average conductivity of 2220 uS/cm.

Geysers

Geysers have constrictions in their plumbing systems that prevent water from moving freely to the surface where heat would escape. Water beneath the constrictions creates a buildup of steam. Eventually the steam pushes water past the constrictions and the geyser erupts.

Upper Geyser Basin

The majority of world’s active geysers are in the Upper Geyser Basin, including Old Faithful. Only four other places in the world have large concentrations of hydrothermal features: Russia (Kamchatka), Chile, New Zealand, and Iceland.

The heat for the hydrothermal features comes from Yellowstone’s volcano. Molten rock or magma may be as close as 3-8 miles (5-13 km) underground. Rain and snow supply water that seeps down several thousand feet (more than a kilometer) below the surface where it is heated.

Underground cracks form a natural plumbing system. Hot water rises through the plumbing to produce hot springs and geysers.

Use Caution in Hydrothermal Areas

• Stay on boardwalks and designated trails.
• Hydrothermal water can severely burn you.
• Never run, push, or shove.
• Supervise children at all times.
• Do not scratch hydrothermal mats.

You are responsible for your safety.

Think safety, act safely. Yellowstone is a dangerous place.