Circa

B.C.

B.C.E.

A.D

C.E.

Decade

Century

Age

Era

Volcano

Plain

Desert

Mountain

Hill

Plateau

River

Forest

Lake

Ocean

Coast

Valley

Island

Pennisula

Swamp

Oasis

Canyon

Cliff

Cave

Dune

Strait

Gulf

Bay

Harbor

Delta

Istimus

Land Bridge

Primary source

Secondary source

Fossil

Artifacts

Culture

Archaeology

Geography

Landforms

Donald Johanson

Climate

Enviroment

Region

Resources

Hominid

Hunter-Gatherers

Society