There's going to be a party at the Petrified Forest later this month. It's a centennial celebration, which is a little hard to explain, given that the volcanic episode that created these acres of natural history occurred about 3.4 million years ago and it has been a destination for the excited scientist and the curious tourist for 144 years.

The celebration (May 17 and 18 — free on the Saturday, by admission on Sunday) will have music and food and all the hoopla that comes with a birthday party. It will mark the 100th anniversary of the ownership — and dedicated stewardship — of three generations of determined women who have pushed back at State Parks' grandest plans to buy the site, who have made 100 years of pay-as-you-go improvements and created a tourist stop to both marvel at and learn from.

Let's talk a bit about tourism. It has always been a factor in the progression of our history. First came the Native Americans. Then came the tourists.

The Spanish marched up from San Francisco Bay. The first were priests and soldiers, but, for the most part, they were sightseers — tourists. The Fort Ross Russians had no military reason to follow the river upstream or climb the highest mountains. They were taking stories of what was here to see back home to Russia. They were tourists.

Tourism is a leading industry in our county — throw in wine and it is THE leading industry. How that came to be has a lot to do with the progression of transportation — of traveling.

Last month, I wrote about early travelers who — separately and in three languages — in the 20 years before any true settlements here, described the mighty oak forests and compared the area to "an English park."

The traveling writers who followed them would report that there were a lot more wonders to be seen than in any old Sherwood Forest.

In the 1850s, the first tourists came on horseback and in buggies to see the amazing geysers canyon, the No. 1 wonder of the northern frontier. Then, in 1870, a homesteader swinging his pickaxe discovered wonder No. 2 — chunks of wood that look like logs but feel like stone. He spread the word and kept digging, eventually uncovering a complete petrified tree, which he called "The Queen."

As word got out, a paleontologist from Yale made the long trip west to study the specimen, which he and his colleagues determined was Sequoia langsdorfii, an extinct species of redwood, which had been turned to stone by a pre-historic volcanic episode. Right in our own backyard.

Now stagecoaches met the railroad in Santa Rosa and followed the trails to the Big Geysers, passing right through the bailiwick of the old guy known as Petrified Charlie. Charles Evans, a Swedish immigrant who had sailed the seas before settling on the mountain on the eastern edge of Sonoma County — just three miles from the Napa line — had that pioneer sense of a profit to be made. He dug some of the dirt from around those astonishing logs and posted a sign saying "Petrified Forest," adding the amount of the admission fee.

He was in business. Word spread. Charlie's rock-hard bonanza was the talk of the two counties and well beyond.

Charlie died in 1880, the same year that a Scottish writer named Robert Louis Stevenson published his "Silverado Squatters," a journal of his family's stay in an abandoned mine on the slopes of Mount St. Helena. In 1879 Stevenson had paid a visit to Charlie's roadside attraction and, while he seemed more impressed by Charlie himself than by the petrified logs he had uncovered, he devoted an entire chapter of his book to the Petrified Forest.

As Stevenson's readership around the world grew — with "Treasure Island" and "Kidnapped" — so did the relative fame of the forest.

The Petrified Forest passed to Charlie's sister, Christina Ryden, and her daughter, Elizabeth Rohl, known as Petrified Lizzie, of course. In 1888 it was sold to a doctor and a minister who apparently did little to advance the progress of geological science. They sold it (or lost it as a bad debt) to "Boss" Meeker, the Occidental and Camp Meeker logging mogul.

You can't make lumber out of petrified trees. So Meeker hired a succession of managers who welcomed not only tourists but a persistent stream of scientists from all over the world. And some, like Luther Burbank, from close to home.

That transportation-tourism link kicked in again in 1911 when a Studebaker Flanders Twenty Runabout drove in, the first automobile to make the uphill climb.

Enter, in 1914, the matriarch of the modern-age Petrified Forest, the focus of the centennial party. That would be Ollie Bockee (pronounced like a bouquet of flowers). Ollie was a beautiful San Francisco socialite with an unreliable husband, a son and four young sisters, an adventuring spirit and an iron will.

Ollie, seeking property for financial independence as she headed toward a divorce, bought the site with $4,000 down and put her son, Harold, to work building a house and barn.

Just as "higher powers," including the National Park System, began to take notice of the forest, Ollie began her marketing campaign.

She sent off a sizeable chunk of petrified wood to the 1915 World's Fair, the famous Panama-Pacific Exposition in San Francisco, with the Bay Area newspapers taking note and advising that the forest was "easily reachable by automobile."

In 1919 she began excavation of the giant Monarch Tree, all done carefully and by hand; a ban on mechanical digging equipment continues to this day. By 1920 she bought more acreage, expanding the forest to more than 500 acres, which included the huge volcanic Ash Fall that is now visible from the Meadow Trail.

In 1924 she and her buddy, Luther Burbank, sent off a 5,560-pound petrified log to New York City to be displayed, with a proper plaque, in Central Park.

In 1930, Psychology magazine wrote of Ollie's project. The title of the article — "A Girl Who Saw a Fortune in Dead Trees."

Ollie continued to promote and protect the forest with zeal until her death in 1950. Management of the site fell to her sister, Jeanette Hawthorne, who proved to be as fierce a guard of the family treasure as Ollie.

In Jeanette's tenure of nearly 20 years, distinguished scientists continued to visit and magazines like National Geographic reported their findings. A coffee shop opened and a plaque commemorating author Stevenson's 1879 visit was dedicated.

After Jeanette's death in 1969, her daughter Davida Conway took charge, applying for and receiving a State Historical Landmark designation. In 1989, Sonoma State geology professor Dr. Terry Wright helped design the new Meadow Trail, which provided access to the Ash Fall and a breathtaking view of Mount St. Helena, another important remnant of that long-ago volcano. Wright also created the educational displays that explain the geology of the site and of the larger, Sonoma and Napa areas.

More overtures from the State Parks system were met with the standard family answer, attributed to Davida Conway: "We're doing what the State would do and paying taxes besides."

Sisters Janet and Barbara Angell, the daughters of Davida's sister, Fay Angell, currently lease the forest from the family trust, sharing management responsibility. Janet, a lawyer, and Barbara, a nurse practitioner, grew up, with their sisters, across Petrified Forest Road from the site. Their mother, Fay, who died in 2010, was Ollie's niece, Jeanette's daughter, and Davida's sister. The message here being that it's all in the family.

And will continue to be.