Divergent boundary

[1][2] Current research indicates that complex convection within the Earth's mantle allows material to rise to the base of the lithosphere beneath each divergent plate boundary.

At divergent boundaries, two plates move away from each other and the space that this creates is filled with new crustal material sourced from molten magma that forms below.

A seafloor map will show a rather strange pattern of blocky structures that are separated by linear features perpendicular to the ridge axis.

If one views the seafloor between the fracture zones as conveyor belts carrying the ridge on each side of the rift away from the spreading center the action becomes clear.

Scientists had been studying polar reversals and the link was made by Lawrence W. Morley, Frederick John Vine and Drummond Hoyle Matthews in the Morley–Vine–Matthews hypothesis.

Continental-continental divergent/constructive boundary
Oceanic divergent boundary: mid-ocean ridge (cross-section/cut-away view)
Bridge across the Álfagjá rift valley in southwest Iceland , that is part of the boundary between the Eurasian and North American continental tectonic plates.
Map of Earth's principal plates (divergent boundaries shown as red or pink lines)