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8th Science
Chapter 4 - A Beka Book
| Term | Definition |
|---|---|
| Weathering | The process by which rocks are broken down by the forces of nature |
| Physical weathering | the breakdown of large rocks into fragments by physical forces such as ice temperature and grit |
| Physical weathering does not change the ___ ___ of the minerals that compose a rock | chemical composition |
| Ice wedging | occurs when rainwater r melted ice soaks into tiny cracks in a rock and freezes |
| Exfoliation | the process of weathering which involves the breaking or peeling away of rock in layers |
| At the base of the mountain or cliff the broken fragments collected in huge piles of rock are called ___. | talus |
| Chemical weathering | When minerals in a rock react chemically with air or water, the minerals may weaken or even dissolve away causing the rock the crumble |
| The main agent of chemical weathering is ___. | water |
| Carbonic acid | A weak acid produced when carbon dioxide in the air dissolves in rain or groundwater |
| Oxidation | A process in which the oxygen in air and water reacts with minerals like calcium and form new compounds |
| Chemical weathering changes the ___ of the original mineral(s). | composition |
| Chemical weathering is usually a(n) ___ process. | slow |
| Erosion | Once rocks have undergone weathering physical processes like wind or running water may carry away the rock fragment by this |
| Caves | networks of underground cavities |
| The process of erosion often begins with ___. | rain |
| Runnoff | The excess water that occurs during a heavy rain in which more water falls than the ground can evaporate. |
| ___ is a major source of runoff. | Snow |
| Rills | Narrow shallow cuts in the soil |
| Gully | A channel in the ground that cannot be repaired by ordinary cultibation |
| The process of that forms gullys | Gullying |
| Ravine | What a gully forms into if the process of gullying is not stopped; fills wildly with water in rainstorms but dries up quickly |
| Of all the forces of erosion, ___ ___ has the greatest effect on the earth's surface | running water |
| Rivers | Large streams that carry water form the mountains to the sea |
| Headwaters | the source of a river; brooks and streams that are in mountainous or northerly areas |
| Load | The material carried by a stream |
| River sediments are said to be ___, or arranged into layers according to their size. | sorted |
| River system | Consists of all the streams that merge and flow toward the sea as a large river |
| The region of land drained by a river system | Drainage basin (aka. water-shed) |
| Drainage divide | Separates two adjoining drainage basins |
| Great Divide | The western drainage divide of the Mississippi River Drainage Basin |
| Eastern Continental Divide | The eastern drainage divide of the Mississippi River Drainage Basin |
| Tributaries | Numerous streams that continue to feed into the river at various points along its course |
| The level or early level land that borders a river and is covered by water in flood time | floodplain |
| levees | natural ridges that form along the edges of a river's channel |
| Meanders | winding looping curves in a river |
| When a meander is bypassed and becomes cutoff from the rest of the river it forms a crescent shaped body of water known as a(n) ___ ___. | oxbow lake |
| Delta | a fa shaped or triangular depsoit extending from mouth of river to sea; forms when rives reach the ocean and deposits a load of sediment |
| The sediments are left on the plain in a delta-like deposit called a(n) ___ ___. | alluvial fan |
| Large caves formed from limestone | caverns |
| Dripstone | Calcium carbonate deposited by water droplets |
| Stalactite | dripstone that hangs from the ceiling |
| Stalagmite | dripstone that is on the fllor |
| Column | Dripstone formation that occurs when a stalactite and stalagmite form |
| A large funnel-shaped depression in the ground | sinkhole |
| karst | Regions of the earth's surface where limestone is exposed and abundant |
| ___ and ___ continually change the shape of the shoreline. | Waves, currents |
| Beaches | gently sloping coasts covered by sand or pebbles |
| Beaches are among the most ___ ___ of all shoreline features | rapidly changing |
| Bars | ridges of sand or gravel that waves and currents build |
| The body of water lying between the barrier island and the coast | sound |
| Promontories | high ridges of rock and land that project out into the sea along deep-water shorelines |
| A vertical face of rock | sea cliff |
| Sea caves | Sea archesIndentations in a sea cliff |
| Sea arches | narrow formations of rock that arch out into the water from the coastforms form the continued erosion of sea caves |
| Glacier | A thick ice sheet that slowly moves under its own weight |
| Continental glacier | vast sheets of glacial ice that cover immense areas of relatively flat land |
| Ice caps | smaller ice sheets |
| Valley glaciers | "rivers of ice" that slowly flow down form mountainous regions into valleys |
| Crevasses | deep cracks and fissures in the surface of a glacier |
| cirque | a huge bowl shaped depression |
| A sharp ridge that divides two cirques | arete |
| When three or more cirques cut into a mountain peak, they transform it into a sharp, steeple shaped point called a(n) ___. | horn |
| Sometimes glaciers carve out valleys along the coastline; as the glacier melts, the valley fills with seawater, creating a ___. | fjord |
| Large hard rocks pushed along by the glacier produce deep grooves and scratches called ___ in the bedrock. | striae |
| Till | Formed when a glacier partially melts, or retreats, during warmer weather, the huge quantities of these broken rocks that it carries are dumped on the rcok |
| Maraine | An accumulation of till left by a retreating glacier |
| When a glacier advances again in the winter, it may overrun its old moraines, smoothing the till into low hills called ___. | drumlins |
| As the glacier melts, streams of water called ___ often develop beneath it washing sand gravel and other sediments from beneath the ice; these deposits are called ___. | meltwater, outwash |
| Kettles | Large holes left form the melting of huge hunks of glacial ice lodged in till or otuwash |
| Kettle lake | Forms when a kettle fills with water |
| Terminal moraines | Piles of debris left at the front of the glacier |
| Snout | the front of the glacier |
| Lateral moraines | piles of debris left along the side of the glacer |
| Ground moraines | Piles of debris from the bottom of the glacier |
| Medial moraines | Piles of debris left by the middle of a retreating glacier |
| Glaciers were once much more ___ than they are now. | extensive |
| Ice Age | A period of widespread glaciation |
| Glaciers and cold weather did not cover the ___ ___ during the Ice Age. | entire earth |
| Aeolian process | Features such as sandstone arches and uniquely shaped rocks are the result of this process |
| Wind transports sediments by what three methods? | 1. Suspension 2. Saltation 3. Creep |
| Suspension | Carries fine particles over long distances |
| Saltation | Bigger particles that are lifted for a short distance and then dropped abruptly |
| Creep | when the wind cannot lift the particles so they are rolled in short bursts through this process |
| The most important effect of wind erosion is ___. | deflation |
| Deflation | The removal of loose particles of sand and soil by the wind |
| Blowouts | The wind often forms these shallow depression where material has been blown away |
| Sandstorms | Typically carry coarse sand particles and fine particles of dry soil and occur in deserts |
| Dust storms | Carry only dust |
| Areas where soil is blown away are ___, but areas where the soil is deposited are ___. | harmed, improved |
| A huge deposit of clay and silt | Loess |
| Sand dunes | huge heaps of loose windblown sand common is deserts and near beaches |
| Windward side of a dune | The side of the dune that faces the wind |
| Leeward side | The side facing away from the sind |
| Crescentic dunes | Most common dune; the points face away from the wind |
| Parbolic dunes | arch-shaped and superficially similar to crescentic dunes except that the open end of the arch points to the windward instead of leeward side |
| Tranverse dunes | Resemble ocean swells or wives lie in straight lines perpendicular to the direction of the winds |
| Star dune | look like a pyramid with several out reaching arms |
| Abrasion | The eroding action of windblown sand |
| When rock is loosened by weathering it is subject to what? | erosion by gravity |
| Mass wasting | The process in which gravity causes the down-slope movements of rock soil volcanic ash snow or ice |
| Soil creep | The slow down-slope movement of soil and rock fragments; the most g widespread form of slow mass wasting |
| Mudflows | Rapid movements of loose water saturated soil |
| A mass of ice and snow abruptly dislodging from a mountain face forms a(n) ___. | avalanche |
| Landslides are what? | Sudden slides of huge masses of rack or soil down a slope |
| Debris slide | Involves rock fragments and other loose materials found in coarse soil |
| Earth slide | Made of fine soil and small pebbles |
| A landslide consisting primarily of bedrock | a rock slide |
| Rock fall | Form of mass wasting that occurs when individual rock fragments abruptly break off the sides of a steep cliff |
| Terracing | The modifying of a smooth slope into a series of level stair-like steps |
| Strip croppimng | to plant alternate strips of erosion prone crops with strips of erosion preventing crops |
| Breakwater | Objects designed to reduce the force of waves |
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nelsonclan
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