Earth’s History Test Review Quietly take a seat Take out a sheet of paper

Describe uniformitarianism

uniformitarianism Earth is constantly changing since its creation The same forces that changed earth’s surface millions of years ago, are changing it now What are those forces?

uniformitarianism Earth is constantly changing since its creation The same forces that changed earth’s surface millions of years ago, are changing it now What are those forces? Weathering, erosion, plate movement and resulting landforms and events (seafloor spreading, creation and destruction of crust, volcanoes, earthquakes, mountain building, creation of seas)

What is Continental Drift What evidence supports it?

Continental Drift evidence mc Matching fossils Matching rock formations Puzzle-like continents Tropical fossils in arctic climates

What is plate tectonics? What evidence supports this theory?

Plate Tectonics evidence: sea floor spreading magnetic reversals Earth’s lithosphere is broken into plates Some are continental, others are covered with oceans Plates move on the asthenosphere Convection currents in the asthenosphere move the plates Plate composition and direction of movement determine landforms and events

Convergent processes and landforms, examples Continental – Continental _____________________________________ Continental – Oceanic ______________________________________ Oceanic – Oceanic ______________________________________ Oldest crust is found where and why?

Convergent processes & landforms Continental – Continental folded mountains (earthquakes) Example: himalaya mountains Continental – Oceanic coastal volcanic mountains, subduction zone, trench, earthquakes Example: andes mountains Oceanic – Oceanic island arcs, subduction zone, trench, earthquakes Example: Aleutian Islands, Japan Oldest crust is found where and why? Continental crust b/c it is not subducted

Divergent Boundary Plates movement ________________ Process ____________________________ Creates _____________________________ Real example

Divergent Boundary Plates move apart Process: sea floor spreading Create mid-ocean ridge mountain ranges, Rift valleys, Creates new crust Real example: mid-atlantic ridge

Transform Boundary Movement Creates Real example

Transform Boundary Movement slide past eachother Creates faults, earthquakes NO MOUNTAIN BUILDING Real example: san andreas fault

Hot Spots What are they? Commonly occur where (where don’t they occur?) Real example

Hot Spots What are they? Stationary magma plumes under tectonic plates. The hot spot does not move. The plate moves over the hot spot Commonly occur where (where don’t they occur?) commonly are not occur at plate boundaries Real example: hawaii

If new crust is created by magma, why is the earth roughly the same size it was 4.6 billion years ago? 6mc 6mc

If new crust is created by magma, why is the earth roughly the same size it was 4.6 billion years ago? 6mc 6mc Crust is created at divergent boundaries at the same rate it is destroyed in subduction zones at convergent boundaries.

What events & landforms at: 1. Indian-Australian plate and Pacific Plate 2. Eurasian Plate and Indian-Australian Plate 3. Juan de Fuca Plate and North American Plate 4. Antarctic Plate and Indian-Australian Plate

What events & landforms at: 1. Indian-Australian plate and Pacific Plate C, o-o, island arc, subd z, trench, destry, EQ 2. Eurasian Plate and Indian-Australian Plate C, c-c, folded mtns, EQ 3. Juan de Fuca Plate and North American Plate C, c-o, coastal volc mtns, subd z, EQ, Trench, destroy 4. Antarctic Plate and Indian-Australian Plate D, mid ocean ridge, rift, create

What is superposition? What are the rules to order rock layers?

Superposition Earth’s history is revealed in rock layers as well. Sedimentary rock layers contain fossils, intrusions, cracks, unconformities and folds that tell us what was happening on earth’s surface at different points in time Comparing fossils (index) and rock layers tell us what happened first, second…..relative age Oldest layer is on the bottom, younger on top Distortions in rock layers occurred after the layer(s) they changed

Using the diagram to the right Describe the age of the fossil Using layer 1 Using layer 4 Using layer 2

You have found an area of North Carolina with an abundance of fossils. What kind of rock are you looking at? How do you know?

You have found an area of North Carolina with an abundance of fossils. What kind of rock are you looking at? Sedimentary rock How do you know? Heat and pressure involved in igneous and metamorphic rock process destroys remains

What kind of evidence do we get from ice cores and tree rings?

Ice core Global climate evidence Bubbles  CO 2 levels in ancient air indicate temp levels. Also used in current computer model predictions of global warming. Volcanic ash  evidence of volcanic eruptions Pollen  spores evidence of environmental conditions Tree rings Ring width  very specific, local information about precipitation levels Burn scars  forest fire evidence Irregular banding  crowding, wind conditions

Absolute Age Allows the calculation of ancient rock and fossil age..puts a number on age Half life of radioactive material found in volcanic intrusions & volcanic ash. (the time it takes half a radioactive sample to break down into a stable material)

How much time has passed if 75% parent material remaining 25% parent material remaining

How much time has passed if 75% parent material remaining ½ yr (6 mos) 25% parent material remaining 2 yrs

Carbon-14 dating uses a radioactive isotope of carbon. It has a half life of 5,700 years. It has a useful time of ~60,000 years. It is ONLY USED on remains of LIVING THINGS Other isotopes (uranium, chlorine..) have very long half lives (millions of years.) They have a useful range of millions to billions of years. They are used to date rock layers, fossils and remains of NONLIVING THINGS

Geologic Time Scale What is it How is it divided Describe the major time periods

Geologic Time Scale What is it? Fossil evidence in rock layers How is it divided major events (extinctions & radiations) Describe the major time periods Precambrian: single celled life, most of earth’s history is in precambrian time, ends with mass radiation of life Paleozoic era: most life in the sea, age of amphibians, ends with mass extinction Mesozoic era: age of reptiles, dinosaurs, no ice— humid, ends with mass extinction…meteor strike Cenozoic era: current, age of mammals

 1. Hadean  2. Archean  3. Proterozoic  4. Phanerozoic  #1-3 make up Precambrian Time  Eons -> Eras -> Periods -> Epochs  Change in name is due major geologic or climatic events!! EONS – largest division of time

90% of Earth’s history Lasted nearly 4 billion years of Earth’s 4.6 billion years Volcanic ash & dust ->clouds formed - >rain Single-celled micro-organisms in ocean at end No animals No plants PRECAMBRIAN TIME

544 million years ago – present Explosion of Life! 3 Eras: – Paleozoic Era – “Age of Amphibians” – Mesozoic Era – “Age of Dinosaurs” – Cenozoic Era – “Age of Mammals” Phanerozoic Eon

544 mya – 248 mya All life in ocean until end Fish developed Reptiles, Insects, Ferns developed – moving life onto land at end Ends with a Mass Extinction kills 90% of all ocean species Paleozoic Era = “Ancient”

248 mya – 65 mya Dinosaurs rule! Small mammals, birds, flowering plants Ends with Mass Extinction due to meteor strike off Mexico ->dust cloud blocked sunlight, killed plant life and affected food chain Mesozoic Era = “Middle”

65 mya – Present Large warm-blooded mammals, modern birds, flowering plants Animals developed migration techniques Tertiary Period Quaternary Period = last 2 million yrs – Ice ages – 1 st modern human fossils = 100,000 yrs old – Humans are 7 seconds of 12 hour clock!! Cenozoic Era =“Recent”

Why study fossils?

They show us how life has changed over time. The Geologic Time Scale show us how changes in earth’s surface & climate have affected changes in organisms.