Silurian or Ordovician
Holmes' first geological time scale.
The correspondence of Holmes' values with those of today is
remarkable, given the limitations of the techniques available to
him in 1911.
with considerable suspicion. One of the foremost American
geologists of the time, George Becker, had recently published
his Age of the Earth , concluding, after having reviewed all the evi-
dence provided by the various hour glass methods, that the age
of the Earth 'must be between 70 and 55 million years', and that
consequently 'radioactive minerals cannot have the great ages
which have been attributed to them'. In similar vein John Joly,
in a serious attempt to reconcile radiometric ages with those
obtained from the sedimentary record, found it impossible to
accept the incredibly slow rates of deposition inferred by the
If the recorded depths of sediments have taken 1400 million years to
collect, the average rate has been no more than one foot in 4000 years!
This seems incredible: and if we double the depth of maximum sedimen-
tation it still remains incredible. But, if possible, still more incredible is