Granodiorite Boulder from Antarctica - Menlo Park, California - Rock and Mineral Displays on Waymarking.com

This boulder from Antarctica is one example of a series of large blocks of rocks from various locations, which are on display around the USGS Campus in Menlo Park. There is a self-guided tour of the campus available at the visitor center.
Text of Sign: “This boulder was collected in the Ross Sea during the 1984 research cruise of the USGS ship S.P. Lee. It was dredged at a depth of 2000 meters (6,500 feet) from the flank of Iselin Bank, the northern extension of a wide basement ridge 100 kilometers (60 miles) wide. It is reportedly one of the largest samples yet collected from the Antarctic continent. The composition of granodiorite is similar to plutonic rock located in the Transantarctica Mountains situated onshore 700 kilometers (450 miles) to the west. It is, however, believed to have been carved from granitic rocks on Iselin Bank itself. If so, it represents a fragment of the slab of continental crust left behind during the break-apart of Antarctica, Australia and New Zealand about 80 million years ago.”