Tuesday, June 3, 2008

Classic Papers in Geology - A Geoblogosphere Carnival

Shutter Ridge on the San Andreas Fault near Pinnacles National Monument

Following the lead of Brian at Clastic Detritus, who followed in turn an idea at Skulls in the Stars, I offer a few comments on my personal take on classic papers in geology. There are so many great choices, research presented by people who were so close to grasping the meaning of the next great paradigm, that the researchers who followed were able to connect the dots and see the big picture. The stories of the larger battles over deep time, uniformitarianism, evolution, and plate tectonics are fascinating, and they color so much of what I teach in my classes.

I had a professor who insisted that we read the original works (in the original dusty volumes; we had a GREAT library at Pomona College) in order to better appreciate the mindset of these creative and intuitive people who made the giant leaps in our field. I have to admit that as a college student, I was lazy, and just wanted to know what they learned, and get to the test. My attitude has since changed, and I occasionally go back to some of the original sources to remind myself how our geological knowledge was gained, often at great cost.

In California and the west, extraordinary advances have taken place in the earth sciences, due to the variety of plate boundaries, and the spectacular exposures of bedrock in the desert regions that lie east of the Cascades, Sierra and Peninsular Ranges. A wonderful resource in this respect is a GSA publication from 1999 called Classic Cordillean Concepts: A View from California edited by Eldridge Moores, Doris Sloane and the late Dottie Stout. They collected the original works, going back to the Gold Rush days, and published them along with some present day analysis of how our understanding of these concepts has evolved.

I had a personal connection to one of the classic papers: the 1953 work by Hill and Dibblee,
San Andreas, Garlock, and Big Pine faults, California; a study of the character, history, and tectonic significance of their displacements. This paper was the first to describe huge lateral offsets along the San Andreas, as much as 350 miles, in a time when a single mile of lateral offset was controversial. By demonstrating that vast amounts of displacement had occurred, Hill and Dibblee helped to lay the groundwork for the eventual acceptance of plate tectonics.

Thomas Dibblee (1911-2004) was an extraordinary geologist who personally mapped around a quarter of the state of California. His exploits are legendary. I met a geologist who accompanied Dibblee on a mapping trip, and Dibblee, even at an advanced age, more or less ran along outcrops, recording the strike and dip in his notes without using a compass. The geologist couldn't believe he could do it and whipped out the old Brunton, and found that Dibblee's notes were spot on.

Mason Hill worked his entire career at Richland (later ARCO), and collaborated with Dibblee on a number of studies related to the search for oil fields in central California. The 1953 paper was an outgrowth of that work. In retirement, Mason was a constant presence at Pomona College where I was an undergraduate, and later a technician. I was able to occasionally assist in a small way with some of his research. His 1981 GSA paper included a map of the San Andreas system that he let me design. It was the first time I ever saw anything of my work in print. Mason was kind enough to write me a letter of recommendation for graduate school, and I have to think that given my less than stellar grades, it carried enough weight to gain me entrance to a good program. It was a privilege to work with him.

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