Another key to the pattern of this first expansion is the aforementioned configuration of the three plates of the seabeds of Central America. These three extensional plates push the continents of North and South America outwards and upwards, creating compressional fault lines along the west coasts of both continents.

The sliding and extensional faults of Central America are the hinge between the two landmasses. This hinge is at the antipode of the original impact and entry point, the Himalayas.

Note: see Plate-Tectonic sub-section ( ptss ) for 'Sliding' and 'Compressional' faults, and 'Extensional Plates'.