the long period of time before people developed systems of writing and written language
a scientist who uncovers evidence, or proof, from the past archaeology.
the study of past cultures through the things that remain such as buildings, tools, or pottery .
an object made by people long ago
to move from one place to another
a huge ice sheet
a period of time when glaciers covered great stretches of land
city in New Mexico near where archaeologists found many early human-made objects
a prehistoric "land bridge" that once connected Asia and North America