Travel Reference
In-Depth Information
were gone, the rivercourses disrupted, the great interior valley turned from
rolling grassland to farm. But some things had
not
changed: The California
fossils were still endemic, and there was still very little understanding of how
to correlate these west coast Cretaceous rocks with the standard reference
sections in Europe. Because the fossils in these regions were not of the same
species, it was impossible to use fossils as means of comparing the ages of the
two regions. Yet the breakthroughs achieved in Europe and by the Deep Sea
Drilling Program in the fields of integrated biostratigraphy and magne-
tostratigraphy offered a new key to the puzzle. And then one of my new col-
leagues at Davis offered the opportunity.
Professor Ken Verosub had graduated in physics from Stanford Univer-
sity but had gravitated to the study of paleomagnetics. His initial suggestion
that I might incorporate the then relatively new field of magnetic sampling
into more traditional biostratigraphic methods got me started. At the time I
had absolutely no idea how such sampling might take place. The Alvarez ar-
ticles about sampling the Apennine Mountains in Italy mentioned only that
"oriented cores" were taken from the rocks. But how? In my experience,
cores were usually several inches thick and extracting them required oil-
well-drilling techniques. I envisioned large, toothy metal bits being slowly
screwed down through rock. Yet, the Italian work had required that thou-
sands of "oriented cores" be obtained; and I knew that thousands of oil rigs
had not been marched over the Italian countryside. My introduction to the
tool designed to obtain oriented cores was thus a pleasant surprise: It was a
chain saw, but a chain saw mutated somehow into a coring device. The
chain and saw were gone; the motor remained and was used to turn a hollow
metal tube coated with diamonds, which cored the rock.
This Rube Goldberg apparatus worked. The long tube attached to the
motor was a small diamond drill about an inch in diameter. The motor turns
it at high speed, and the thousands of industrial-grade diamonds coating the
tip are sufficient to cut several inches into any type of rock. The drill exca-
vates a 2 - or 3-inch core; this core is then popped off with a chisel. If the
exact attitude of the core is known (the direction of its long axis and its
angle of dip into the earth are measured with a compass), then it contains all
