Final answer:
The east coast of North and South America features a passive margin, characterized by a flat Coastal Plain and accumulated sediments from rifting of Pangaea.
Step-by-step explanation:
The type of continental margin found on the east coast of North and South America is known as a passive margin.
This region is characterized by the Coastal Plain which extends from New England to Texas along the Atlantic Ocean and the Gulf of Mexico.
The topography of this area is relatively flat, and it consists of accumulated sediment derived both from the continent and from shallow marine environments. These sediments often contain mature sediment and marine fossils, indicating a tectonically inactive edge which has not experienced significant tectonic activity since the rifting of Pangaea.