On October 27 the state of Jalisco marked the first Primavera Forest Day, which has the aim of reminding citizens every year of the natural wonder lying directly west of Guadalajara.
The Primavera Forest is huge, covering 30,500 hectares. It starts precisely where the city ends, and stretches west for about 23 kilometers, while the distance north to south measures 18 kilometers.
Although it is called a bosque (forest), it is much more than that. Its pine-and-oak-covered hills mark the exact location of the Primavera Caldera, a volcano that erupted dramatically 94,000 years ago, shooting 40 cubic kilometers of ash and pumice (called jal in Mexican Spanish) straight up into the air in a Yellowstone-type explosion which affected the whole planet. The word Jalisco refers to the area where this jal fell back to Earth.
Recently, the forest’s managers have created an interpretive trail where visitors can experience the caldera’s unique giant pumice horizon, consisting of blocks of pumice up to eight meters in diameter, a phenomenon that has attracted geologists from all around the world to the Bosque la Primavera.
The magma that caused that great explosion still lurks beneath the woods and manifests itself in boiling-hot rivers and hissing fumaroles.