According to the ecological approach to understanding city dynamics, existing populations begin to move out of the inner city as it decays, and it is gradually repopulated by ethnic minorities. given what we have studied about class, race, and other social problems, the reason for these shifts may be that ethnic minorities

The reason for this shifts is because of the fact that ethnic minorities have only few economic resources by which they are also willing to live in an inner city that is decaying as they can afford it than other city that they can’t afford and in addition, exiting populations does not like ethnic minorities.

answer; ///he could not explain why the continents drifted;