Upper portions of the grand canyon show undisturbed horizontal layers of sedimentary rock. which of steno's principles explain this? a. principle of original verticality b. principle of original horizontality c. principle of superposition d. principle of lateral continuity

Ahill is made of rock particles of different sizes. which of these agents of erosion probably causes the hill to form? a- waves b- glacial ice c- wind d- flowing water

What characteristic of the basin that feeds the congo river system affects movement in central africa? a. the center of the basin is a dense rain forest. b. it is the center of ethnic conflict in the area. c. wildlife on the savanna makes it too dangerous to travel. d. the basin is surrounded by desert.

All of the following statements ere innovations that benefited farmers during the second agricultural revolution expect a. the iron plough b. the railroad c. animal husbandry d. plant domestication