Where on Earth? - November 2014

Clues for November 2014:

1. This rock arch composed of pillow basalts forms part of the seaside headlands in what is the largest urban national park in the U.S., according to the National Park Service.

2. In addition to the pillow basalts, other rock types found nearby include diabase, weathered graywacke, folded cherts and serpentinites. The varied and well-studied geology of the area documents a roughly 200-million-year record of ocean crust formation, subduction, faulting, erosion, sea-level change and other processes.

3. A short (almost a kilometer) walking trail that takes visitors to an historic and still-active lighthouse — built in 1855 and moved to its present location in 1877 — offers the closest vantage of the arch from land, as well as vistas of the surrounding coastal areas and a certain colorful suspension bridge.


Name the feature and its host state.

Scroll down for the answer


Answer: Pillow basalts make up the impressive rock arch at Point Bonita in California’s Golden Gate National Recreation Area, the largest urban national park in the U.S. The geology of the
surrounding area, which includes many other rock types, documents a 200-million-year record of crust formation, subduction, faulting, erosion and sea-level change. Photo is by Robin Rohrback.

November Winners:
John D. DeMartini (McKinleyville, Calif.)
Ellen Herron (Chapel Hill, N.C.)
John Karachewski (Walnut Creek, Calif.)
Glen S. Pearson (Red Bluff, Calif.)
Doris Sloan (Berkeley, Calif.)

To submit your photographs to our Where on Earth? contest, send them via e-mail to



01 Nov 2014