Searching for Big Trees in Deep Time

In most people’s minds, John Muir is most closely associated with Yosemite, a place he loved and worked all his life to protect. Fewer people know that Muir was the first to propose that his beloved valleys were carved by glaciers during ancient ice ages, and to gather scientific evidence that the glaciers in the Sierra above were still moving and cutting. Muir had a sense of place that included a dimension of “deep time.” That deep-time sense carried over to his love of big trees. Two of his favorites, the Giant Sequoia and Coast Redwood, are conifers—relatively ancient compared to other angiosperm trees like oaks and maples, but not as old as their evolutionary relatives in the Araucaria family. Muir saw his first living Araucarias in Australia and New Zealand on his round-the-world tour in 1904. In 1905, in the Petrified Forest in Arizona, he realized he was looking at the fossils of an ancient forest that was probably dominated by 200-million-year-old relatives of the living trees he had just seen: an Araucaria Forest in deep time. On his last international journey in 2011, Muir deliberately sought out the two species of Araucaria found in South America, Araucaria angustifolia in southern Brazil, and Araucaria araucana in the Andes of Chile. Using the notes and sketches in his journals, I have followed his footsteps to the places where he finally saw those species, over several trips to Chile beginning in 2012, and more recently to Brazil in 2026. Seeing the same places Muir saw—and maybe even some of the same individual trees—more than a century later evokes a sense of place embedded in the flow of time, ultimately reaching very deep.