October 27,2011

ObjectiveTo learn how the

geologic timeline was made and how the length of the various periods are different

AgendaProgress reports –

need to be signed by Parent/guardian

Geologic History Notes

Project –highlightsLab: Geologic

Timeline

Structure of the Time Scale

The Geologic Time Scale

Based on their interpretations of the rock record, geologists have divided Earth’s 4.56-billion-year history into units that represent specific amounts of time. Taken together, these time spans make up the geologic time scale.

Structure of the Time Scale

12.4 The Geologic Time Scale

Eons represent the greatest expanses of time. Eons are divided into eras. Each era is subdivided into periods. Finally, periods are divided into smaller units called epochs. There are three eras within the Phanerozoic eon: the Paleozoic, which means “ancient life,” the Mesozoic, which means “middle life,” and the Cenozoic, which means “recent life.”

The Geologic Time Scale

Precambrian Era

The Precambrian era lasted from Earth’s formation 4570 until 542 million years ago (mya).

The first cells appeared in the Precambrian era.

Paleozoic Era

The Paleozoic era lasted from 542 to 251 mya.

Paleozoic is a Greek word meaning “ancient life.”

Paleozoic Era

Rocks from the Paleozoic Era contain fossils of snails, clams, corals, and trilobites.

Paleozoic Era

Animals with backbones began to appear.

At the end of this era, the continents that existed during this time period collided to form a new supercontinent, Pangaea.

Mesozoic Era

The Mesozoic era lasted from 251 to 65 mya. This era is often called the Age of Reptiles.

Cenozoic EraThe Cenozoic era began 65 mya and is

still going on. The common name for the Cenozoic Era

is the Age of Mammals.

Cenozoic Era

Mammals diversified into a variety of species including land mammals, sea mammals, and flying mammals.

Cenozoic means “recent life.”

Mastadon Stromatolites Apatosaurus

(Brontosaurus) Orthoceras Nautiloid Eurypterids Trilobites Velociraptor Chesapecten jeffersonius

( State Fossil) Carcharodon Megalodon Spinosaurus Cave Bear (Ursus

speleaus) Ichthyodectes ctenodon Coelophysis Quagga Giganotosaur

Ohmdenosaurus Zephyrosaur Wuerhosaurus Torosaurus latus Elasmosaurus platyurus Manny: woolly mammoth Sid: ground sloth

(Megalonyx) Diego: saber-toothed

tiger (Smilodon) Scrat: saber-toothed

squirrel (Leptictidium) Dab: dodo Carl: Embolotherium Frank: Brontotherium