Linear trough in the Earth's crust in which rocks were deposited in South America in the Mesozoic Era (248-65 million years ago) and Cenozoic Era (65 million years ago to the present). A complex history of volcanism, uplift, block faulting, and erosion led eventually to the present configuration of the Andes Mountains
Complex of aboriginal cultures that evolved in the Andean region (see Andes Mountains) of western South America before the arrival of the Spanish conquistadores in the 16th century. Unlike the peoples of the Mesoamerican civilization to the north, none of the aboriginal Andean peoples developed a system of writing, though the Inca devised a sophisticated system of recording numbers. In its level of cultural development and technical expertise in the arts and crafts, however, this civilization constitutes a New World counterpart to those of ancient Egypt, China, and Mesopotamia. See also Chibcha; Chimú; Moche; Tiahuanaco