Stop 12

Retrace your steps to the walkway between Buildings 1 and 2. To the left of the entrance of the Wisteria (Wisteria frutescens) arbor, you will see a large boulder of orbicular diorite from the Sierra Nevada in which the rounded “orbs” crystallized before the surrounding rock solidified. Although geologists understand how molten magma cools and crystallizes into solid granitic rock, this particular type of diorite presents many mysteries as to exactly how the orbs solidified. Note the various textures within some of the orbs. Some orbs are stratified or layered internally, while others are homogenous throughout. The question remains—What was happening in the magma chamber while this rock crystallized?

In late April and early May, the shiny gray and black of this obicular diorite is framed by the red and white blossoms of the surrounding rare rhododendrons, “Mi Amor” and “Beauty of Littleworth”, as well as a rare deciduous tree, a Veitch Magnolia, (Magnolia X. veitchii ‘Peter Veitch’), hybridized in 1907 from the Himalayan species M. campbellii and M. denudata, to the left of the diorite.

Continue walking under the Wisteria arbor between the buildings. At the end of this arbor is a large slab of polished New Hampshire granite, containing a large pegmatite vein. The gray mineral is quartz, the black mineral is biotite mica, and the white and pink crystals are different feldspars. The slab is a gift from Stanford University and matches one in the Stanford School of Earth Sciences.

Take a moment to look around on other side of the granite slab and notice the steel bracings on Buildings 1 and 2. These braces were added to the buildings in 1979 as structural reinforcement to reduce the effects of ground shaking during an earthquake. During the 1989 Loma Prieta earthquake, the bracings proved their worth as neither building suffered any serious damage.

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