Wegener proposed that the continents were plowing through a stationary ocean floor. But, his peers argued that continents could not push through the ocean floor without fracturing, because crustal rock is too brittle. And no evidence of fracturing had been found.
Plate Tectonics Section 2: S eafloor S preading Harry Hess
In the early 1960s, Harry Hess proposed that hot, less dense material below Earth’s crust rises toward the surface at the mid-ocean ridges. Then, it flows sideways, carrying seafloor away from the ridge in both directions. This theory is known “ seafloor spreading ”.