Geology Reference
In-Depth Information
To make matters worse, at the end of the war Bob Lawson
had left Vienna for a lectureship in physics at She~eld
University, so Holmes' access to the Viennese experts on atomic
weight determinations was cut o¬. This seriously hampered his
age dating work. Already the necessity for complex chemical
separations of radiogenic lead imposed severe limitations on
the uranium-lead method and restricted its application to
rare minerals containing appreciable amounts of uranium. The
problem was compounded by the presence of both uranium and
thorium derived lead and also by the existence of appreciable
amounts of 'ordinary' lead. No longer was it acceptable simply
to measure the total amount of lead in a sample, it was now
necessary to know which isotopes you were dealing with and
this was only possible by determining their atomic weights. So
even with access to the Viennese lab, the delicate and extremely
accurate atomic weight determinations only complicated further
the already complex chemical analyses. It was just too time-
consuming for everyone concerned and after the war when the
students returned and time for research was severely curtailed,
the method largely fell into disuse. For a while Holmes' dream
of building a geological time scale became less tangible as more
urgent matters required his attention. By 1920 his financial
situation had become so acute that it was imperative he get a
better paid job.
In 1911 a pioneer series of lectures on oilfield geology had been
given at Imperial College, and within a very short time an Oil
Technology division of the Geology Department was borne. Many
of the students from this course found jobs in the booming oil fields
of Burma and on their return would tell stories of their adventures.
There seemed to be no alternative: late in 1920 Holmes resigned
from Imperial College and accepted a job as Chief Geologist to the
newly formed Yomah Oil Company (1920) Limited.
