Spreading Seafloors - Four Revolutions in the Earth Sciences - page 121

Duringlarge-scale convective circulation thebasaltic layerbecomes akindofendlesstraveling
belt on the top of which a continent can be carried along, until it comes to rest (relative to the
belt) when its advancing front reaches the place where the belt turns downward and disappears
into the earth. . . .
Thecurrentshavebecome sufficiently vigoroustodragthetwohalvesoftheoriginal contin-
ent apart, with consequent mountain building in front where the currents are descending, and
ocean floor development on the site of the gap, where the currents are ascending. . . .
Most of the basaltic magma would naturally rise with the ascending currents of the main
convectional systems until it reached the torn and outstretched crust of the disruptive basins
left behind the advancing continents. . . . There it would escape through innumerable fissures,
spreading out as sheet-like intrusions within the crust, and as submarine lava flows over its
surface. 17
Compare those words with the words of Dietz and Hess and ask which better de-
scribes the concept of a spreading seafloor. Arthur Holmes wrote them in his 1944
textbook, nearly two decades before Dietz and Hess published their ideas.
Neither Dietz in his 1961 article nor Hess in his preprint cited Holmes. It seems
highly likely that neither had read his textbook, as their subsequent comments
mention only his 1929 article, then more than three decades old. 18 The diagram
that accompanies Holmes's 1944 text is very similar to figure 8 , taken from the
1929 article, and his words clearly convey the concept of seafloor spreading. In
his topic, Holmes had to rely on prewar information, which included almost none
of the wealth of geophysical and oceanographic data available to Dietz and Hess.
Holmes was understandably wrong about the details but right about the fact of sea-
floor spreading and its cause: convection in the Earth's mantle.
It is this writer's belief that if the words of Dietz, Hess, and Holmes were spread
without attribution before a neutral jury of present-day geologists in a blind test,
on the question of which of the three authors deserves priority for seafloor spread-
ing, a hung jury would result.