Why do people in the Marquesas Islands mostly live in mountain valleys?

In the Marquesas Islands, human habitation is largely restricted to narrow mountain valleys primarily because the islands lack coastal plains and protective coral reefs.12

Because these volcanic islands feature high, craggy terrain with sharp, twisting contours that drop abruptly toward the sea, they do not provide the flat land necessary for traditional coastal settlement. Consequently, residents have historically lived in these deep, narrow valleys where streams provide access to water and land suitable for agriculture, such as taro, breadfruit, and coconut trees. This settlement pattern, which involves clusters of houses spreading up the sides of the valleys, has been a consistent feature of the region since prehistoric times.123