In places, as
along the western edge of the American continents, continental margins coincide with plate
boundaries and are active margins. Where
continental margins lie inside plates, they are
passive margins.The breakup of Pangaea created
many passive margins, including the east coast of
South America and the west coast of Africa.
Passive margins are sometimes designated rifted
margins where plate motion has been divergent,
and sheared margins where plate motion has been
transformed, that is, where adjacent crustal blocks
have moved in opposite directions. The distinction
between active and passive margins is crucial to
interpreting some large-scale features of the
toposphere.
Earth’s tectonic