Relative aging, fossils, natural disasters
Rocks breaking down into smaller pieces
Water that moves over Earth s surface Causes sheet erosion Moves downhill Forms rills and gullies
Erosion creates valleys, waterfalls, flood plains, meanders, oxbow lakes Deposition creates alluvial fans, deltas, add soil to flood plain
Underground water Chemical weathering-water combines with CO2 to form carbonic acid, breaks down limestone Forms caves, stalactite (roof) and stalagmite (floor)
Continental glaciers-covers much of continent, island Valley glaciers-long, narrow glacier from snow and ice in mountain valley
Plucks rocks Breaks rocks Drags rocks which scratches bedrock Deposits sediment when it melts- till, moraine, kettle
Energy comes from wind blown across water s surface Break apart rocks on shore Abrasion-headland, arch, cave Deposit sediment-beaches, spits, sandbars, barrier beaches
Deflation-wind removes surface materials, Dust Bowl Abrasion-Polishes rock, little erosion Deposits-sand dunes, loesssediment that is finer than sand
Create 3 Venn diagrams comparing different types of erosion. You must include 3 different facts for each section. Worth 27 points. Example: Wind 3 facts 3 facts Water 3 facts
Soil Loose, weathered material on Earth s surface in which plants can grow.
Soil Formation Rock broken down by weathering Sediment mixes with materials on surface Soil horizon-layer of soil that is different in color and texture
Soil Layers Topsoil- crumbly, dark soil that is a mixture of humus, clay, and other minerals Subsoil-Clay, other particles, little humus
Living Organisms in Soil Humus-formed from organic material Litter-layer of dead plant leaves Decomposers-break down organic matter to form humus Earthworms, and other burrowing animals mix soil
Importance of Soil Fertility-ability for plants to grow depend on nutrients in soil Dust Bowl-loss of topsoil, devastating Soil conservation by farmers Erosion control
Fossils Preserved remains or traces of living things
Fossil Theories A theory is a well-tested concept that explains a wide range of observations. Paleontologists study fossils. Evolution is the gradual change in living things over long periods of time. An organism is extinct if it no longer exists on Earth.
How fossils form Living things die and are buried in sediments Sediments harden into rock and preserve shapes of organisms Sedimentary rock
Molds and casts Most common Mold-hollow area in sediment in shape of organism Cast-solid copy of the shape of organism
Petrified Fossils Minerals replace all or part of an organism Petrified wood
Carbon Films Extremely thin coat of carbon on rock Carbon from organism left behind in shape of organism
Trace Fossils Provide evidence of activities of organisms Footprints Trails Burrows
Preserved Remains Organism trapped in tar, or amber Rancho La Brea tar pits Freezing in Siberia Protects organism from decay
Age compared to the age of other rocks Absolute age-number of years since rock formed
Atoms of one element break down to form atoms of another element Half-life- time it takes for half of the radioactive atoms to decay Carbon-14- measure amount of Carbon-14 left in organism to determine absolute age
Tell relative ages of the rock layers in which they occur
In horizontal sedimentary rock layers, the oldest layer is at the bottom and each higher layer is younger than the layers below it.
Extrusion- lava that hardens on the surface Always younger than the extrusion below it Intrusion- Magma that hardens into igneous rock Always younger than the rock layers around and beneath it Faults-Break in Earth s crust Younger than rock it cuts through Unconformity- Gap in geological record Rock layers lost because of erosion