diagram showing how to restore two continents separated by oceanic crust.
Continent A is shown in green; continent B is shown in olive. Oceanic crust
is shown in shades of brown. The age of the oceanic crust is labelled.
The present-day location of the mid-ocean ridge is given by the black line
labelled 0 Ma. On this and subsequent diagrams on this page, fracture zones
(black lines) are used in the restoration for the diagrams on the right;
they are not used in the diagrams on the left. The yellow areas are regions
adjacent to the continents where the age of the oceanic crust is not unknown;
the orientations of fracture zones are also not known.
in the restoration involves "removing" oceanic crust that is 0 Ma to 50
Ma old. The white areas on this diagram correspond to the regions where
this crust was "removed."
in the restoration involves squeezing the blocks together to eliminate
the white gaps produced by "removing" the oceanic crust that was 0 Ma to
50 Ma old. For the diagram at left, the blocks where squeezed together
in a direction perpendicular to the trend of the "bands" of oceanic crust.
In the diagram at right, blocks where squeezed together in a direction
parallel to the fracture zones.
in the restoration involves removing crust that is 50 Ma to 100 Ma old.
The results are shown above.
in the restoration involves removing crust that is 100 Ma to 150 Ma old.
The results are shown above. The next step involves removing the "yellow"
crust. For the diagram at left, after removing the "yellow" crust, the
blocks are simply squeezed together in a right-left direction. For the
diagram at right, the blocks can be squeezed together in a number of different
directions (see arrows for possible examples), but the exact direction
is not known because the orientation of fracture zones is unavailable for
the "yellow" crust.
restorations are shown above. The restorations differ because that
on the left always moved the blocks from right to left, whereas that on
the right moved the blocks parallel to the fracture zones for all stages
except the last, which used independent evidence to determine the restoration
direction (the circular features are required to be adjacent to one another
in the final restored state). In the restoration at right, notice that
the region of the present-day equator (0°) on continent B is adjacent
to the region which at the present day lies at a latitude of ~13°.
In the restoration at left, present-day and restored latitudes much one