Earth History

Sections 1. Precambrian Earth 2. Paleozoic Era 3. Mesozoic Era 4. Cenozoic Era

Precambrian Earth

Geologic Time Scale Geologic Time Scale The geologic time scale is a record of Earth’s History The Earth is 4.6 Billion Years Old Precambrian (4.6 bya – 543 mya) Paleozoic Era (543 mya – 250 mya) Mesozoic Era (250 mya – 65 mya) Cenozoic Era (65 mya – Present) Geologic Time Scale

Origin Of Earth 4.6 Bya – Earth Formed Solar Neblua Hypothesis – Cloud of dust and gas collapsed by the force of gravity Formed the sun and the other planets in the solar system 4.0 Bya – Earth had a stable crust, oceans and atmosphere

Origin Of Life 3.8 Bya-First life forms evolved Stromatolites – Mounds of cyanobacteria Were photosynthetic – Consumed carbon dioxide, produced oxygen Created Earth’s oxygen supply

First Continents 3.5 Bya-The first continents began to form Convection began due to unequal heating of the mantle (plate tectonics) Caused the landmasses to move apart

Atmosphere 2.5 Bya – Atmosphere became dominated by oxygen 1.8 Bya – First cells with nuclei appeared Eukaryotes – WILL Need to know for Biology!

NC Mountains 1.7 Bya- Present day North Carolina formed 1.3 Bya-The first mountains of North Carolina formed Grenville mountains (no longer exist due to erosion) Formed by Grenville Orogeny Oldest rocks of NC formed. Presently exposed in the Appalachian Mountains

First Multi-Celled Organisms 1 Bya – First multi-celled organisms 600 mya – First sponges and worm like animals appeared

NC Flooding 620 mya-North Carolina was pulled apart by tectonic forces Seas covered North Carolina Volcanic island arcs developed along NC-VA border

Paleozoic Era

Cambrian Explosion 542 mya-”Cambrian Explosion” – Major diversification of life First vertebrates North Carolina was still underwater

Rodinia 540 mya-North America and Europe/ Africa moved towards each other Formed Kings Mountain Belt Formed supercontinent Rodinia

Taconic Orogeny 496-440 mya-Taconic Orogeny: The coastline of present day Appalachian Mountains collided with Iapetus Plate (Oceanic Plate) Formed volcanic mountains in present day North Carolina

Paleozoic Fish 444 mya – Fish were dominant First jawed fish Sea scorpions Trilobites Mollusks First land plants

Acadian Orogeny Acadian Orogeny (400-325 mya): A continent called Avalonia collided with present day North America Continued the formation of the Appalachian mountains. Also lead to the formation of Pangaea

Coal Forests 359 mya-Wetland forests dominated the Appalachian area The decayed organic matter from the trees lead to coal that is currently mined today

Alleghanian Orogeny Alleghanian Orogeny (325-260 mya): Africa collided with North America. Pangaea was fully assembled. Appalachians were fully formed, in the center of Pangaea

Permian Mass Extinction 251 mya – Permian Mass Extinction Drop in sea level, resulted in 95% of all life going extinct Possible changes in climate 75% of amphibians, 80% of reptiles disappeared

Mesozoic Era

Appalachian Erosion 251 mya-Appalachians began to erode Wind and rain → Sediment was carried to lower lying land or sea Pangaea was breaking up North Carolina was near the equator, had a tropical climate

Mesozoic Events 250 mya – Dinosaurs first appeared → Were dominant organisms First mammals appeared First crocodiles Ichthyosaurs-Dolphin like organisms in the seas

Pangaea Separation 200 mya-As Pangaea separated the Atlantic Ocean formed Outer margin became the outer banks Atlantic Ocean began to open up

Mesozoic Life 200 mya- Dinosaurs were still dominant Mammals began to grow in numbers → Still not dominant First birds and lizards

Coastal Plain Flooding 145 mya-65 mya: Coastal Plains were underwater but sea level began to drop Pangaea continued to split up Southern landmasses broke up → Africa and South America created

Mesozoic Extinction 65 mya – Mass extinction: All dinosaurs went extinct Most geologists think a meteorite hit in the Yucatan Peninsula in Mexico which caused this → Supported by presence of iridium

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Cenozoic Era

Cenozoic Life 65 mya - Mammals began to dominate. First large mammals appeared World’s climate was tropical however was starting to cool 57 mya – Coastal Plains were now above sea level

First Mammals 55 mya – First modern mammals evolved Whales diversified Coastal Plains flooded again → Seas stretched up to the Western Piedmont

Modern Mammals 23 mya – Modern mammals and birds appeared Grasses dominated the Earth Ocean retreated from the coastal plains

Blue Ridge Mountains 5 mya-Blue Ridge and Piedmont were as they are today First human ancestors Coastal Plains were flooded again but waters receded Sand Hills Developed – Streams eroded piedmont and sent sediment to the coastal plains Fall Line – Sharp drop off in elevation. Located around Fayetteville

Ice Age 1.7 mya-”Ice Age” began. 18,000 years ago – Glaciers melted There is present day evidence in the Coastal Plains Glacial Till 18,000 years ago – Glaciers melted

Human Civilization 10,000-15,000-North Carolina’s forests began to develop Look as they do now 9,000 BC-Human civilization began

Assignment Make a timeline showing the history of the earth with each Period and Era Listed After making the timeline, begin looking over notes and preparing to study for our Exam Wednesday