The most common border-marking geological formations between Portugal and Spain are rivers, not mountains. There is no specific mountain range marking the border.
The longest border in Spain is the border with Portugal to the west. The border with Portugal runs from the north of Spain to the south.
the tigris and euphrates rivers border mesopotamia
It has 1,000,23 rivers in he North of Spain.
Portugal shares Spain's western border.
Five major rivers in Spain are theTajo (Tagus)EbroDueroGuadianaGuadalquivir
The border between Spain and Portugal is long and it has different landforms along it, including rivers, mountains and flat areas.
Spain shares a border with Portugal.
Andorra is not in Spain, but it does border it.
Ohio and Mississippi Rivers
Portugal, France, and Andorra all share a border with Spain.
France is on the north east border of Spain