Left: Roger, worrying about core recovery. Middle: Coring rig at sunset. Right: Working day and night.
Our earlier studies of similar layers in modern lakes
had convinced us that each pair of light and dark layers represented one
year. Our goal was to measure each pair of layers and build an exceptionally
long history of annual climate change. We drilled, cored, sliced, polished,
and photographed more than 1000 feet of rock.
Left: Roger, worrying about core recovery. Middle: Coring rig at sunset.
Right: Working day and night.
We measured the layers from a photographic print which,
unrolled, stretched more than a mile. We began before the era of computers
and put computers to the task when they became available. I still have some
data sheets processed on MANIAC, the machine at Los Alamos that helped build
the bomb and was donated to the university. Finally, as our series of numbers
grew longer, and as computers grew smaller, unrolled before us, was a 200,000-year
plot of climate change.
A plot of the 200,000-year Castile time-series. The largest changes
in climate occurred in cycles of about 2500 years 20,000 years, and 100,000
years. Yellow bands are salt beds.