03/05/2009 03:36:00 SPRING 20089---INTRODUCTION TO OCEANOGRAPHY--- GEOL 107 Study Guide #5---Prof. W. Berelson Note: these guides are designed to help you decide what is important to know from the lecture and book material. They may not cover every single topic I might ask about on an exam, but they cover most topics. To study for exams, use this guide, use notes from class, use textbook. -What makes a wave break? When a wave feels the bottom of the ocean the energy is compacted and it itterupts the circular motion and when the crest separates from the base it breaks -Why does the <a href="/keyword/east-coast/" >east coast</a> of the US have barrier islands, name two ways that barrier islands may form. When sediments accumulate on submerged rises they form islands When water rises over the <a href="/keyword/sand-dunes/" >sand dunes</a> creating lagoons which expand to rest of ocean -Explain how a groin and a sea wall impact the coast, especially the beach. Seawalls reduce the impact of waves on the beach but increases erosion on the sides of the wall Groins are jetties that extend into the water and the sand accumulates on the side of the updrift and increases erosion on downdrift side -Why does Palos Verdes have cliffs and a rocky shoreline (in some places)? ** -When a river discharges into the ocean what becomes of the sediment load? It forms a delta or fan with the heaviest and largest sediment closest to the mouth of the river and spreading out in a triangular shape -What s the difference between a summer and winter beach? Winter beach: water is colder which makes bigger waves which have more energy and therefore more sand is taken away from beach o Winter beaches are smaller and steeper -Explain erosion and the creation of a marine terrace. Erosion occurs by wave action beating the base of cliffs The action of the water mixed with the sediment acts like sandpaper Marine terrace: ** -How can you tell the direction of waves approaching the beach from the pattern of sand deposited around a groin? You can look at which side of the groin has the most sand and sediment against it and know that the waves are moving in that direction b/c they are depositing the sand in that direction -A coastline with cliffs is a coastline with net erosion or deposition? Net erosion -Since humans have been around, erosion of the land surface has increased, yet the sediment load of rivers has decreased, why? Dam, I should have gone to class. Dams allow the water to go through which allows for erosion but they don t allow the sediment to go through so theres no sediment in the ocean and the ocean needs sediment so its eroding more things to gain the sediment back Terms Longshore drift Waves approach the shore at an angle but go out straight Same as a littoral drift Delta Deposit of sediment at the mouth of a river Beach profile (Berm, offshore bar, beach face, dune) Berm: accumulation of sediment that runs parallel to shore, marks the normal limit of sand deposition from waves Offshore bar: sand bar Beach face: the part of the beach that tourists go to DuneLittoral drift Above Groins, jetty, sea wall Groins jut out into the ocean Seawall blocks waves Jetty ** Wave cut terrace Smooth level terrace found on erosional coast that marks submerged limit of rapid erosion Spit** Good Luck