Enumerate the geologic time scale and description the events for each period
Answer (1)
Answer:1. Precambrian (4.6 billion – 541 million years ago)Earth formed, first rocks appearedOrigin of life (bacteria, algae)Oxygen began to accumulate in the atmosphere2. Paleozoic Era (541 – 252 million years ago)Cambrian – Explosion of life, many marine animals appearedOrdovician – First vertebrates (jawless fish), coral reefs formedSilurian – First land plants and insects appearedDevonian – Age of fishes, first amphibians appearedCarboniferous – Vast swamp forests, first reptilesPermian – Supercontinent Pangaea formed, mass extinction at end3. Mesozoic Era (252 – 66 million years ago)Triassic – First dinosaurs and mammalsJurassic – Dinosaurs dominated, first birds appearedCretaceous – Flowering plants appeared, dinosaurs went extinct at end4. Cenozoic Era (66 million years ago – Present)Paleogene – Mammals and birds diversifiedNeogene – Early humans appeared, grasslands spreadQuaternary – Ice ages, modern humans developed
