Planet Earth
The Earth s Structure Crust the outermost and thinnest layer of Earth Mantle the layer of rock between the Earth s crust and its core - rocks are plastic soft and easily deformed
The Earth s Structure Core center of the Earth - Inner core solid metal - Outer core liquid metal; surrounds the inner core
Plate Tectonics Plate Tectonics theory that Earth s surface is made up of large moving plates, which may have moved throughout Earth s history
Plate Tectonics - In 1911, Alfred Wegner, a German geologist saw that the continents fit together like a huge jigsaw puzzle. - East coast of South America fits into the west coast of Africa
Plate Tectonics - Wegner thought that all of the continents were once together in a super-continent he called Pangea
Pangea: all lands, supercontinent
Plate Tectonics - Explains mountain formation, volcanoes, earthquakes, and how similar animals could have lived at the same time on what are now widely separated continents.
Fossil Distribution
Plate Tectonics - The crustal plates are thought to move due to Earth s internal heat causing convection circulation in the mantle.
Convection
Convection
Earth s Plates Lithosphere the thin outer shell of Earth, consisting of the crust and the rigid upper mantle - made up of several tectonic plates
Earth s Plates Asthenosphere the zone of the mantle beneath the lithosphere that consists of slowly flowing solid rock - plates of lithosphere float on top of the asthenosphere
Plate Boundaries Divergent Boundaries two plates spread apart - Magma from the mantle rises into the rift valley between the plates - Magma molten rock within the Earth
Plate Boundaries - New material is added to the edge of each plate becoming new ocean floor - Forms a rift valley surrounded by high mountains
Plate Boundaries - Can form volcanoes Volcanoes often form hills or mountains as materials pour or explode from a vent Vent opening through which molten rock flows onto Earth s surface
Plate Boundaries Convergent Boundaries plates are moving towards each other
Plate Boundaries Subduction process in which a tectonic plate dives beneath another tectonic plate and into the asthenosphere. Ocean trenches, mountains, and volcanoes are formed at subduction zones.
Plate Boundaries Transform Fault Boundary two plates move against each other Fault a crack in the earth created when rocks on either side of a break move
Brainstarter What is plate tectonics?
Plate Boundaries Causes earthquakes Seismology study of earthquakes Focus area along a fault where the earthquake is initiated
Plate Boundaries Epicenter the point on Earth s surface directly above the focus of an earthquake Richter Scale scale that expresses the relative magnitude of an earthquake
Rocks & Minerals
Rocks & Minerals Mineral a natural, inorganic solid with a definite chemical composition and a characteristic internal structure
Rocks & Minerals Igneous Rock rock formed from cooled and hardened magma or lava
Rocks & Minerals Intrusive igneous rock formed from magma that cools within the earth - contains more, larger crystals
Rocks & Minerals Extrusive igneous rock formed as it cools on Earth s surface - contains fewer, smaller crystals
Rocks & Minerals Sedimentary Rock rock formed from compressed or cemented deposits of sediment
Rocks & Minerals Deposition the process in which sediment is laid down
Rocks & Minerals Metamorphic Rock rock formed from other rocks as a result of heat, pressure, or chemical processes
Weathering 1. Physical or mechanical weathering a. Ice frost wedging b. Plants roots grow into cracks in rocks
Zion National Park, Utah
Weathering 2. Chemical weathering a. Reaction with oxygen
Weathering b. CO 2 + H 2 O H 2 CO 3 (carbonic acid) As it seeps into the ground it can for weather rock underground. (Mammoth Cave)
Weathering c. Acid rain (high in sulfuric or nitric acid)
Erosion Erosion - the removal and transportation of materials by running water, wind, waves, ice, underground water, and gravity.
Erosion Water Erosion - water scours out places on the surface and carries new sediments away.
Erosion There is a direct relationship between the velocity of the water and the size and the amount of the sediment it can carry.
Erosion Quickly moving rivers can carry away a lot of sediment, and create large canyons.
Erosion Glacial Erosion - large masses of ice moving can carve the surface it rests on, often creating u-shaped valleys.
Fjords of Norway
Erosion Wind Erosion wind carries sediment that creates a sandblaster effect
Geologic Time
Geologic Time Relative Age one event occurred before or after a different event
Geologic Time Absolute Age a date is assigned to an event relative to a fixed measure - uses radioactive decay - Carbon-14 Dating - Compare the amount of 14 C present in tissue to current 14 C/ 12 C ratio
Principle of Superposition Assuming no change in the position of the rock layers, the oldest will be on the bottom, and the youngest will be on top.
Principle of Original Horizontality Layers of sediment are generally deposited in a horizontal position
Faunal Succession Fossils can be used as age markers - Index Fossils fossils that are widespread in extent, yet occurred within a restricted interval of time
Principle of Cross-Cutting Relationships cross-cutting rocks are younger than the rocks they cut across.
Granite Dike Inclusion Gabbro Illustration of principle of cross-cutting relationships, as seen in an outcrop containing three different igneous rocks. The thin pink (aplite) dike cuts across or intrudes the other two rocks, hence it is the youngest of the three units present. The black (gabbroic) rocks are also dikes, intruding the granite, which must then be the oldest unit. The evidence for this is given by a small inclusion of the granite enclosed in the basalt.
Inclusions Pebbles and fragments included in sediments and lavas must be older than the host rock containing them.
Deformation any rocks affected by a deformational event (i.e. folding, tilting) must pre-date the deformation episode.
Unconformities breaks in the geologic record
Brainstarter Is the greenhouse effect good or bad for the environment? Why?
Brainstarter Using the diagram on the board, if we know that the index fossil in level 5 is 5.6 million years old and the index fossil in level three is 6.2 million years old, what would be an estimate for the fossil in level 4? Why?
Development of an Angular Unconformity A. Original Horizontal Beds B. Folding or tilting of strata C. Tilted rocks are then eroded, leaving behind a level surface. D. Subsequent deposition on the surface results in an angular difference between the two rock strata - with little evidence for how much time has passed between the deposition of the two strata.
The Atmosphere
Atmosphere Trophosphere the atmospheric layer closest to Earth s surface where nearly all weather occurs
Atmosphere Temperature Inversion atmospheric condition in which warm air traps cooler air near Earth s surface results in increased air pollution
Atmosphere Stratosphere atmospheric layer above thermosphere; contains ozone layer
Atmosphere Ozone (O3) shields life on Earth s surface by absorbing much of the sun s ultraviolet radiation
Atmosphere Mesosphere layer above stratosphere Thermosphere layer above mesosphere
Atmosphere Barometric Pressure (air pressure) the pressure due to the weight of the atmosphere
Greenhouse Effect Atmospheric gases (Carbon dioxide, water vapor, etc) allow solar radiation to enter the biosphere, but slow the loss of heat to space.
Greenhouse Effect Greenhouse effect Carbon dioxide, methane, water vapor, and other atmospheric gases trap heat energy and maintain Earth s temperature range.
Greenhouse Effect Good keeps Earth warm enough Bad increased levels of CO2 may lead to global warming Melt polar ice caps, ocean levels rise, drought
Water Cycle (Hydrologic Cycle) Evaporation transformation of water from a liquid to a gas. - water evaporates as the sun heats up the earth
Water Cycle (Hydrologic Cycle) Condensation transformation of water from a gas to a liquid.
Water Cycle (Hydrologic Cycle) As water vapor rises after evaporation, the cool air at higher altitudes causes the vapor to condense into tiny water droplets that form clouds.
Water Cycle (Hydrologic Cycle) When these water droplets become large enough, they return to earth in the form of precipitation
Water Cycle (Hydrologic Cycle) Types of precipitation: rain, snow, sleet, or hail
Water Cycle (Hydrologic Cycle) Transpiration evaporation of water from the leaves of plants
Water Cycle (Hydrologic Cycle) Runoff precipitation runs along the surface of the ground until it reaches a river or stream that then carries the water to an ocean or lake
Water Cycle (Hydrologic Cycle) Ground water water that filters into the soil
Water Cycle (Hydrologic Cycle) - Ground water will eventually reach a body of water or be taken up by the roots of plants
Clouds Cirrus thin and wispy; high altitudes Stratus sheetlike and layered; lower altitudes Cumulus white and fluffy; various altitudes