sediments: silt, sand or rock moved by water, wind or glaciers

ice ages: periods of time when glaciers covered a large part of Earth

carbon-dating: a way to tell how old the remains of something once living are by measuring the amount of a type of carbon

millenia: thousands of years; 1,000 years is called a millenium

savannah: a flat grassland with little or no trees in a hot and dry climate