Moffett Field in Santa Clara County, California — The American West (Pacific Coastal)

Granodiorite Boulder From Antarctica

Photographed by Adam Margolis, June 9, 2026

1. Granodiorite Boulder From Antarctica Marker

Inscription. 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 Transantarctic 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.

Topics. This historical marker is listed in these topic lists: Exploration • Natural Features • Science & Medicine • Waterways & Vessels. A significant historical year for this entry is 1984.

Location. 37° 24.713′ N, 122° 3.342′ W. Marker is in Moffett Field, California, in Santa Clara County. It is at the intersection of S. Akron Road and Severyns Avenue

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on S. Akron Road. Touch for map. Marker is at or near this postal address: 450 Severyns Avenue, Mountain View CA 94043, United States of America. Touch for directions.

Regionally, this marker is in California’s San Francisco Bay Area

and on the Coast Ranges.

It is also on the American Pacific Coast.

Globally, it is in North America,

on the Ring of Fire,

in the Pacific Rim,

in the Western Hemisphere,

in the Western World,

and in the Anglosphere.

Historically, it finds itself in what was once New Spain

and also Mexico’s Alta California.

Other nearby markers. At least 8 other markers are within walking distance of this marker: Andesite Block from Mt. St. Helens (here, next to this marker); The NASA U-2 Story (about 300 feet away, measured in a direct line); Patrol Squadron Fifty (about 400 feet away); Shenandoah Plaza (approx. ¼ mile away); Lockheed P-3 Orion (approx. ¼ mile away); Lewis S.G. Braxton III (approx. 0.3 miles away); Site of the John W. Whisman Home (approx. 0.4 miles away); NASA Ames Research Center (approx. half a mile away).

Photographed by Adam Margolis, June 9, 2026

2. Granodiorite Boulder From Antarctica Marker

Credits. This page was last revised on June 18, 2026. It was originally submitted on June 10, 2026, by Adam Margolis of Mission Viejo, California. This page has been viewed 11 times since then. Photos: 1, 2. submitted on June 10, 2026, by Adam Margolis of Mission Viejo, California. • Andrew Ruppenstein was the editor who published this page.