Earth science geology

Earth Science November 12, 2005 Dr Clodfelter The Geologic Time Scale The history of the Earth is broken up into a hierarchical set of divisions for describing geologic time The Geologic Time Scale, cont Highlights of recent fossil finds from throughout geologic time (from most ancient to most recent) are: • Precambrian Era: the first fossil bacteria, sponges, corals, and algae appear • Cambrian Period: abundant invertebrate fossils such as mollusks, crustaceans The Geologic Time Scale, cont • Triassic Period: the first fossils of primitive dinosaurs appear • Jurassic Period: the first fossil mammals and birds; first fossil flowering plants appear • Cretaceous Period: large fossil dinosaurs appear Quaternary Tertiary Cretaceous Jurassic Triassic Permian Carboniferous Devonian Silurian Ordovician Cambrian Precambrian Precambrian Eon 4.5 Billion to 543 Million Years Ago • Nearly thousand million years after the Earth began • The first animals left their traces • Makes up roughly 7/8 of the Earth's history Archaean Era 3.8 to 2.5 Billion Years Ago • The atmosphere was very different from what we breathe today • The Earth's crust cooled enough that rocks and continental plates began to form • Life first appeared on Earth – bacteria microfossils Phanerozoic Eon 543 Million to • Majority of macroscopic organisms, fungal, plant and animals lived • Appearance of animals that evolved external skeletons – like shells – and animals that formed internal skeletons – like vertebrates Paleozoic Era 543 to 248 Million Years Ago • In the beginning, multicelled animals underwent a dramatic "explosion" in diversity • At the end, the largest mass extinction in history wiped out approximately 90% of all marine animal species 3) • • • • Troposphere Bottom layer About 10 miles thick Contains nearly all the atmosphere’s air, water vapor, and clouds Temperature gradually drops until is reaches the stratosphere • Warm air… – Lighter and less dense than cold air – Rises up into the atmosphere – Produces low pressure • Cold air… – Presses down heavily on the Earth’s surface – Produces high pressure Cirrus – Thin, curly, and wispy shapes – Formed in the upper Troposphere – Contain ice crystals Cumulus – Heaped clusters like loose cotton balls – Have flat bases and dome shaped tops – Sometimes build up into thunder clouds Stratus – Formed when Cumulus clouds group together to form a continuous layer – Grayer in color than Cumulus – Bottom of the Stratus layer is in the lower Troposphere A Meteorologist Measures… • • • • • • • Air pressure Temperature Humidity Winds speeds and directions Precipitation (rain, hail, snow, sleet, fog) Cloud types and their heights Visibility – Name used in Asia – Like a tornado and hurricane combined – Rapidly rotating tunnel of air – Moves over land – Can be 300 miles in diameter – Winds speed at more than 125 mph • Similar to cyclones, but much smaller • Sometimes only a mile or so across The name given to a cyclone which develops in the western Atlantic Ocean Infancy Youth Maturity Old Age Alps Rocky Mountains Arbuckle Mountains Cumberland Mountains Colorado River Yellowstone River Rio Grande Red River [...]... islands like the Hawaiian Islands The Mariana Trench The San Andreas Fault Crustal Plate Activity Crustal plate activity can… • Cause earthquakes, volcanic activity, and tsunamis • Earthquakes are signs of the great stresses and which affect the Earth s crust • Over a million earthquakes occur every year • Tsunamis are giant tidal waves and can travel at 500 mph! • Dinosaur Fossil bones have been found... accepted is the Big Bang Theory • Scientists theorize that a meteor hit the Earth at nearly the speed of light (186,000 miles per second!) • Caused a total black out of the sun • This meteor is believed to have caused the Gulf of Mexico Gulf of Mexico • The Earth weighs about 6000 million million million tons • Two-thirds of the earth is covered by water • It would take more than 250 days to walk around... became “just another theory” What are Crustal Plates? • Earth s crust isn’t one continuous surface like the skin of an orange • It is made up of gigantic pieces, like pieces of a jigsaw puzzle • Each piece is called a crustal plate • Some plates form the floor of the oceans while other carry the continents Crustal Plates • Molten rock around the Earth s core heats up the mantle above • Currents of molten... covered by water • It would take more than 250 days to walk around the equator • Every year, North America and Europe separate by 3/4ths of an inch • Scientists predict that life on Earth will only last 50 million more years Earth = Onion • Crust – outermost layer, solid rock, but very thin like skin • Mantle – denser and heavier than the crust, inner part of the mantle is described as “plastic” because... Mesozoic Era Dinosaurs – Evolved in the Triassic Period – Became more diversified in the Jurassic Period – Became extinct in the late Cretaceous Period – Fossils of some of the last dinosaurs to walk the Earth can be found in Montana The Cretaceous/Tertiary Boundary in Montana Cenozoic Era • The most recent of the three major subdivisions of animal history – The other two are the Paleozoic and the Mesozoic... Mesozoic Era 248 to 65 Million Years Ago • • • • • Mesozoic means "middle animals” Lasted 70 Million Years Time of transition The world-continent of Pangaea existed The time in which life as it now exists on Earth came together • Important today because of the fossils and oil left behind Mesozoic Era 248 to 65 Million Years Ago Divided into three time periods: – the Triassic (245208 Million Years Ago) – the... between separating plates – Usually found in mid-ocean and are marked by rugged mountain chains called mid-ocean ridges • As plates move apart a gap continuously opens between them • Molten rock from the earth s interior flows into this gap – New crust is continuously formed Plates and Sea Floor Spreading Crustal Plates • When plates collide, the force can fold and thrust upward to form mountains • Or