When did the colorado river start to form the grand canyon

In the von thunen model of agricultural land use, what is produced closest to the city epicenter? a. dairy, vegetables, and fruits b. field crops, such as corn and wheat c. beef and other animal products d. wood and lumber

Sink holes may eventually for to join a. wide valleys b. zone of aeration c. dripstones d. aquifer

The ethnic conflicts in darfur have led to an attempt to destroy a whole people known as