Peter R. Vogt's article Tree Tectonics (Eos Trans. AGU, 85(36), 338, 7 September 2004) motivates me to present some comments on the phenomenon of seafloor spreading. In particular, I would like to point out a fundamental inadequacy of the commonly accepted model of seafloor spreading. As is well known, a striped pattern of successive positive and negative magnetic anomalies characterizes the oceanic crust. The pattern is produced by the continued accretion of crustal material along active oceanic ridges (seafloor spreading) and the periodical reversals of the magnetic field of the Earth (geomagnetic reversals). On cooling in the magnetic field, the reversals are recorded by the magnetization of the newly formed crust.