Grade 8 Science:Unit 1-Water Systems

Transcription

1 Grade 8 Science:Unit 1-Water Systems Chapter 2: Oceans Cntrl the Water Cycle Origins f cean water Oceans have filled ver hundreds f millins f years Scientists believe the ceans are mre than. Water may have riginally been released frm when the vapr frm the eruptins and. Sme believe the water came frm. Earth's Oceans - pg. 38 There are fur prcesses that lead t the develpment f cean basins: 1. Pieces f the land mve ver the Earth's surface Changes psitin f. Influenced where are lcated 2. Underwater vlcanes are generally fund at. When vlcanes erupt underwater, new ceanic crust is frmed by the ht mlten rck slwly cling and slidifying Vlcanes have built cean flr alng in areas where plates separate. Vlcanes have helped build in areas where plates have cllided and muntain building ccurs.

2 3. Ersin has further develped cntinental drainage systems as material is int the cean basins. 4. When glaciers melt, that they release wears away the earth as it flws dwn t The Ocean Basins - Page : Frm the edge f the water t the "drp-ff" zne. 2. : The "drp-ff" (frm the pelagic zne t the benthic zne) 3. : The wide, flat areas f the cean flr, they are made up f sediment frm earthquakes that cause underwater landslides, r simply by gravity. 4. : Ocean ridges are frmed when tw tectnic plates are pushed apart. Magma zes up thrugh the gap and frms a muntain chain (like a scab). The largest is the mid-atlantic ridge. 2

3 Examples f Canadian institutins that d research invlving ceans: Technlgies used t research the cean flr: waves are sent dwn frm a ship Can be used t map underwater muntains, valleys, and canyns n the cean flr. 2. Orbit the earth, use radar, infrared light, r ther technlgies t measure features n the cean flr. surveys large areas f ceans in a shrt perid f time. gathers infrmatin frm buys abut water and air temperature fr weather statins. 3

4 3. Cameras take high reslutin (clear) underwater phts and vides. Can g up t beneath the surface. 4. Small but extremely strng vehicles (because f the high pressure underwater) that are capable f travelling t great depths. 2 Types: 1. Advantage: 2. Advantage: 5. New technlgy allws peple t dive deeper than ever befre, but they still cannt g as deep as ther technlgies. Advantage: NOTE: STSE: Undersea Adventure; Page 43: #'s 1-4 ; Page 51: #'s 1-8, 11 4

5 Ocean Currents There are mre than 20 majr currents in the wrld Largest: See figure 2.13 n page 52 Lcal cean currents: 1. : water frm near Greenland. 2. : water frm the trpics. These currents run by the Cast f Newfundland and Labradr thrugh the Atlantic Ocean. The warm Gulf Stream Current mixes with the cld Labradr Current and makes. Upwelling Strng winds blw ffshre and push surface water away frm the land. Cld, deep water then rises frm belw t replace the surface water that has been mved ut t sea. Upwelling water cntains lts f. Example: The Grand Banks : Waves n the surface f water are the result f a transfer f energy frm mving air t the water. :The highest part f a wave. : The lwest part f a wave. : Distance frm crest t crest OR trugh t trugh. 5

6 i.e length f a wave befre it repeats itself. : The distance frm trugh t crest f a wave. : Giant waves that can be sent in mtin by n the cean flr, landslides r vlcanic eruptins near the shreline. Ersin & Depsitin : the breakdwn f rcks int smaller particles. : the mving f sediment (weathered particles). : when erded material is drpped r left behind. Ersin and depsitin have a huge impact n ur shrelines. Hw waves interact with shrelines 1. Wave energy is cncentrated n and spreads ut as it reaches. are the parts f the shre that stick ut furthest in the water. are the parts that stick in the mst. 6

7 2. As rcks rub against each ther in the wave water, fragments f rcks are t smaller pieces (pebbles/sand). If the shreline has a slpe, the fragments will get washed ut t sea, leaving a very rcky shreline. If the shreline has a slpe, the rck fragments will build up, creating a sandy beach. 3. Depending n the type f rck that the shreline is made f, can erde the shreline mre quickly., like sandstne, will erde at a faster rate than mre, such a shale. Ex: the red rcks fund in St. Gerge's erde faster than the cliffs f Bell Island in Cnceptin Bay. If a shreline is made f f rck, yu will see uneven ersin. This is hw headlands and bays are frmed. Headlands are always made f a material than bays are. 4. wave energy will erde a shreline mre quickly than wave energy will. Places that have wind will have strnger waves with energy. Hw ersin and depsitin affect Sand and sediment are always being remved ( ) and by waves. Sediments are depsited by size. 2. Depsitin f sediments resulting in lcalized shallwing f the water. 7

8 3. Headlands are erded part way thrugh the headland 4. Occurs when a sea cave is erded all the way thrugh the headland. 5. Occurs when the tp f a sea arch becmes weak and caves in (ersin). The slw rise and fall f the water level f the cean. The upper and lwer edges f a beach are determined by the high-and-lw tide mark. Cnnected t the mtin f the and spinning f the Mn exerts a greater frce f pull than sun since it is t the earth. : the difference between high and lw tides Types f Tides: 1) : Occurs twice a mnth when Earth, Sun and Mn are. Tidal Range is. Causes extra high and lw tides. Extra pull means extra tidal difference 8

9 2) : Occurs twice a mnth when Sun and Mn are at t ne anther. Water is getting pulled in, which cancels ut the verall effect. Tidal range is. Technlgies designed t cntain damage due t waves: 1) : 2) : 3) : 4) : Page 77: #'s 1, 3, 4, 5, 8, 10, 11 Page 78: #'s 2, 3, 4, 6, 7, 11, 12, 13, 14, 15, 17, 21, 22, 24 9