Old Faithful was named for the predictability of its eruptions; however, despite widespread belief, Yellowstone's most famed geyser does not run like clockwork. The current average time between large eruptions, known as the geyser eruption interval or GEI, is about 91 minutes. This is long by historic standards; in the 1950s the wait was only about 60 minutes.

Many factors can change the GEI. Earthquakes in 1959, 1975, and 1983 all lengthened the average time between Old Faithful's eruptions for several years afterwards. Indeed, numerous geological factors affect geyser activity. On a day-to-day basis, changes in atmospheric pressure accompanying different weather patterns likely affect how often geysers go off.

New research from Shaul Hurwitz of the United States Geological Survey along with colleagues from Stanford University and Yellowstone National Park reveals one factor that affects the GEI of Old Faithful and other geysers in the park. This factor is climate. The research, published in the journal Geology, shows how geysers consistently erupt with greater frequency several months after periods of greater precipitation.

The volcanic forces that drive Yellowstone's geothermal features heat the water, which then builds pressure-resulting in an eruption. More rain and snow means that there is more water to heat, and thus more pressure. As a result, the geysers erupt with greater frequency.

Climatologists predict that that climate change will result in less precipitation in the greater Yellowstone area. If it proves true that different levels of precipitation will result in changes to the GEIs of Yellowstone, then many of Yellowstone's smaller thermal features might begin to dry up. In a recent interview with the Silicon Valley Mercury News, Hurwitz suggested that while Yellowstone's most famous geyser will probably remain active, "most likely our grandchildren will have to wait longer for Old Faithful eruptions."

By Karen Wildung Reinhart. Do you remember the fires of 1988? Reinhart examines the 1988 Yellowstone fires and their aftermath. She also explores the answers to the burning questions of 1988; Would fire kill Yellowstone's forests? Would wildlife populations recover? Would Yellowstone itself recover? Rebirth by Fire is a must have for individuals fascinated by the summer that dramatically altered the Yellowstone landscape. Featuring stunning photographs by Jeff Henry and the staff of the Billings Gazette. Price: $19.95 ($16.96 for members).

This year, Yellowstone Association members provided further support for the production of additional mini-documentary web videos, which are featured on the official Yellowstone National Park web site. Users will be able to explore the park in detail with scientists, park rangers, historians, and others, to learn more about Yellowstone's famous attractions and hidden treasures. This multiyear project will eventually result in a complete online multimedia interactive Resources and Issues Handbook, the park's comprehensive informational guide about geology, wildlife, and resource issues. Become a Yellowstone Association member and help support Yellowstone National Park.

Even though most park lodges are filling up for the summer, there is still plenty of room in Institute field seminars based at the Lamar Buffalo Ranch field campus. Located in the heart of the Lamar Valley in the quiet northeast corner of the park, the field campus is the perfect place to learn about Yellowstone's plants, geology, wildlife, and history. These high quality programs are one of the best bargains in the park-tuition averages $100 per day, and students stay in comfortable log cabins for just $25 per night per person.

Here is a sampling of courses with space available:
Wolves of the World
Writing What Nature Reveals
The Bison of Yellowstone
Bears: Folklore and Biology
Shaping the Northern Yellowstone Landscape
From the Ground Up: Botanical Illustration