Wednesday, April 12, 2023

The Earth’s Crust

Sedimentary Rock and The Geologic Time Scale

Canal construction – 19th century. Many layers of sedimentary rock were discovered along with fossils of animals that no longer existed.

Fossils were discovered at multiple sites around the world, including the Grand Canyon. Scientists began to speculate that the Earth was much older that previously thought.

Piecing together the evidence from layers all over the planet (and using radioactive dating techniques) scientists have come up with the Geologic Time Scale of Earth’s History.

The Earth is 4.5 Billion years old and it’s history is broken into four parts or eras:

#1 Precambrian Era - 4.5 Billion to 600 million years ago – first life

#2 Paleozoic Era – 600 to 225 million years ago

#3 Mesozoic Era – 225 to 65 million years ago – The age of dinosaurs

#4 Cenozoic Era – 65 million years ago to present - Recent life