GOSA (The Geyser Observation and Study Association) Black Sand Basin  

Black Sand Basin: - History - Map

Black Sand Basin can be reached by road or by trail. There are a number of interesting and pretty pools and geysers in this basin. It is well worth exploring.

Rocco Paperiello has written a very interesting and comprehensive history of the thermal features at Black Sand Basin. It is well worth a look.

Cliff Geyser

Cliff Geyser: [History] [Picture] [Map]

Cliff Geyser is located on the edge of Iron Creek and is quite picturesque. It was named for the low cliff-like wall that separates the geyser from the creek. Cliff is a fountain-type geyser. Intervals and durations have ranged from a few minutes to hours. During much of the history of the park, Cliff was dormant or an infrequent performer but for a number of years now, Cliff has often been in eruption more than half the time.

The eruption starts from a low pool with the water slowly rising as the eruption continues. Many eruptions stop shortly after the pool reaches overflow but some long duration eruptions may continue long after overflow is reached. Short duration eruptions rarely reach overflow.

Because there is little water to impede the bursts at the start of the eruption, the bursts tend to spread out and be erratic in shape at the beginning. As the pool fills the bursts become more focused and the height increases. The maximum height of about 35 to 50 feet is often reached towards the end of the eruption.

Emerald Pool: [History] [Picture] [Map]

The dark (emerald) green color of this large pool is caused by the blue of its water combining with the yellow cyano-bacteria growing in its bowl. The temperature of the 36 feet wide, 30 to 40 feet long pool is about 155 degrees Fahrenheit.

Handkerchief Pool: [History] [Picture] [Map]

During the first 50 to 60 years of the park, Handkerchief Pool was arguably one of the three most famous thermal features in Yellowstone. The other two being Old Faithful Geyser and Morning Glory Pool. Handkerchief Pool was a novelty for the visitors. Visitors were encouraged to place a handkerchief in the pool, watch the convection currents draw it down into the pool, whirl it around and then return it "cleaned". Fortunately, this type of destructive activity is no longer encouraged. Placing anything into one of Yellowstone's thermal features is now illegal.

The abuse of visitors that started "placing" other objects such as rocks, sparkplugs and logs, was possibly responsible for the demise of this novelty. Handkerchief Pool stopped "functioning" in 1928. Interestingly, a scientific test in 1988, found that the laundry action had returned.

In more recent years, Handkerchief Pool has at times behaved as a quiet pool, a geyser and a spouter. The maximum height seen in the geyser mode is about 8 feet.

Rainbow Pool: [History] [Map]

Rainbow Pool usually lives up to its name. Between the beep blue at the center of the pool and the multicolored cyano-bacteria around the edges of the pool, this is usually one of the most colorful pools in the park. The exception to this rule occurs after Rainbow Pool has had major eruptions. For instance, after the last of these episodes in 1996, the pool dropped below overflow and most of the cyano-bacteria died off. Once the water level recovered, the colors eventually came back but for a while, they were missing.

Rainbow is a fairly large pool, approximately 50 feet across. Usually, it does little more than gently overflow. A few times in the history of the park, though, it has had major eruptions. Some of these eruptions were in excess of 100 feet tall and produced a huge outflow of water. Most of