At this stage there are a number of very important observations relating to the geological mapping shown in the Geological Map of the World that must be fully appreciated. As noted, this seafloor mapping represents a natural tape recording of the growth history of the reversals in the Earth’s magnetic field and, similarly, represents the factual distribution and growth history of the volcanic lavas that make up the seafloor crusts. This preserved history must therefore be strictly adhered to during any crustal modelling study as well as during assemblage of the various crustal plates and continents back in time.
A number of important observations can be appreciated from an initial examination of the Geological Map of the World map. These observations include:
- The pattern of colours representing the ages of the seafloor volcanic lavas confirm that the seafloor lavas are vastly different from the continental crustal rocks. Similarly, the continental rocks, in general, are shown to be more ancient than the seafloor lavas.
- The extrusion of volcanic lava along each of the mid-
ocean- ridge spreading centres represents quenched and solidified volcanic mantle- derived lava; not drowned continental rocks.
- The coloured seafloor striping confirms that all of the oceans contain a mid-
ocean- ridge—currently centred beneath the present day pink coloured stripes—and each ocean is increasing its surface area with time. This increase in surface area is symmetrical about the mid- ocean- ridges within each ocean.
- The maximum age of seafloor volcanic lava, located along the continental margins, is early-
Jurassic in age—about 170 million years old—which is shown as areas of pale blue striping.
- If it were possible to move back in time, each of the coloured seafloor stripes shown must be progressively removed in turn. The corresponding edges of each coloured stripe must then be moved closer together. That is, the erupted volcanic lava must be progressively returned to the mantle where it originally came from.
- When moving back in time, each of the continents must move closer together in strict accordance with the coloured striping evidence. This phenomenon can then be used to accurately constrain the location of the various crustal plates during modelling of the ancient continents and oceans back in time.
- By measuring the surface area of each coloured stripe in turn, this evidence can also be used to investigate any change in seafloor surface area with time, and from this to investigate any changes in Earth radius with time.
It should be appreciated that none, or very little of this magnetic striping, age dating, or bathymetric evidence was available when continental drift, plate tectonic, or Earth expansion theories were first proposed.