NORTH AMERICA’S GEOLOGIC HISTORY THE FOUR MAIN ERAS….. PRECAMBRIAN PALEOZOIC MESOZOIC CENOZOIC

PRECAMBRIAN ERA 4 600 000 000 – 4 000 000 000 years ago Majority of mountain building was done in this era 3 main types of rock Igneous – hot, melted magma that reaches the earth’s surface Sedimentary – eroded igneous rock Metamorphic – igneous and sedimentary rock that is subjected to heat, pressure

PALEOZOIC ERA 570 million years ago, lasted 325 million years Sediments compressed into sedimentary rock to form bedrock. Evolution of organisms – fish, insects, amphibians. Greatest extinction occurred in the latter parts of this period when 80% of life in the seas became extinct.

MESOZOIC ERA 245 million years ago, lasted 180 million years. The beginning of the breakup of Pangaea. Coast Range mountains were being formed. Rocky Mountains started forming as well.

CENOZOIC ERA 66 million years ago to the present. Rocky Mountains formed. Ice ages were happening during this time. This is the age of mammals.

Plates Earth’s crust is made up of tectonic plates Those plates are always moving around, causing earthquakes