At the junction of the Hayward fault and the Calaveras fault, Alum Rock Park in San Jose is a geologist’s paradise: its 20 mineral springs come down through Claremont chert; the Briones formation is full of fossils; Berryessa formation conglomerate greets you at the park entrance and elsewhere. Not surprisingly, the park is home to a wide diversity of plants, including native oaks, bay laurel, gray pine, holly-leaved cherry, buckeye, coffeeberry, holly- leaved redberry, blue elderberry, toyon, hillside gooseberry, sticky monkeyflower and blue witch.

Join geologist and botanist Paul Heiple to explore the relationship between plants and the rocks they grow on. The soil derived from the rocks can be very different from one rock type to another. The plants are not able to move, so they live or die based on what they can get from the soil where the seed fell. This forces the plants to develop adaptations for these differences, which can lead to species that only grow in certain conditions. Come explore this relationship and learn how to read the land for plants you will find, the rocks that might be below, the locations of landslides, and the locations of mineral springs.

Beginners interested in basic rock and plant identification are welcome. The hike distance is 2 miles with 600’ of elevation gain. Bring water and a bag lunch.