Wandering Poles or Drifting Continents? - Four Revolutions in the Earth Sciences - page 100

if each of the rocks sampled had pointed to the pole in the same position as today,
then neither the pole nor Great Britain had moved. 4 But the result was just the op-
posite.
Creer then got the brilliant idea of adding to his map the pole position that John
Graham had measured for the Silurian Rose Hill formation in Pennsylvania. 5 As
shown by the point labeled “S-USA,” it lay well off the position of the Silurian
pole as determined by the polar wandering curve from British rocks. Rocks from
Europe and North America showed the pole in different places at the same time.
FIGURE 13 . Creer's Apparent Polar Wandering Path. The thick dashed line is based on British
rocks. The other lines are pole positions estimated from past climates. “S-USA” is the pole posi-
tion as determined by Graham for Silurian rocks from Pennsylvania. From Creer's 1955 Ph.D.
dissertation. Source : K. M. Creer and E. Irving, “Testing Continental Drift: Constructing the
First Palaeomagnetic Path of Polar Wander (1954),” Earth Sciences History 31, no. 1(2012):
111-145.
Sometimes inscience wecanidentify asymbolic instant, acritical turningpoint,
after which nothing was ever the same. One occurred the first time Rutherford had
enough information to calculate a mineral's age from radioactivity and found it
to far exceed Kelvin's upper limit. Surely another arrived the instant Creer lifted
his pen from plotting the American Silurian pole on his map. The continents had
moved.
Runcorn Converts