C33 Earth Processes

C33 Earth Processes Background Some geologists are interested in beaches because beaches are subject to repeated weathering, erosion and deposition. Beaches are always changing because they are a part of a larger, dynamic system of Earth processes. Challenge Question: How is a beach part of a coastal system?

C33 Earth Processes: Beaches Read page C45 about Beach Formation. In your lab book, write down the main ideas Stop when you see the yellow pencil picture in the margin. Be prepared to tell what you read.

C33 Beach Formation Notes Beach appearance depends on many factors: Wave energy (important) Sediment supply from a river (important) Earth material in the area Weather, tides and seasons Beaches have equal and opposite forces: Constructive = sediment deposition Destructive = waves eroding the sediments

C33 Naturally Changing Coast Read and take more notes. Stop at the pencil When sediment supply is greater than ocean erosion, a delta will form and extend the beach, or coastline, towards the ocean. When ocean erosion is greater than deposits of sediment, the coastline erodes and moves inland. A beach can be washed away or a cliff can form from any nearby high land.

C33 Longshore Current Read and take more notes. Stop at the pencil Longshore Current: ocean water that runs parallel to the shore and moves sand across the face of the beach, making the beach longer as sand moves away from the river. Building anything on the shore can interrupt this current & cause sand to settle out of the water and deposit sand near the structure.

C33 Managing Earth Processes 1 Read and take more notes. Stop at the pencil Dredge: dig up sand & move it. Can be a success but is expensive and a lot of work. It can expose contamination and make land less stable.

C33 Managing Earth Processes 2 Jetty: structure perpendicular to shore, to collect sand before it reaches structures. Collects sand upstream but other side will erode/narrow beach. Breakwater: structure parallel to shore for slowing erosion by reducing wave energy. But it slows the longshore current so sediments deposit in between the breakwater and the beach.

C33 Managing Earth Processes 3 Seawall: structure built against cliff or shore to absorb wave energy/reduce erosion but erosion around the seawall is increased because waves are redirected there. These temporary solutions are effective but may have undesirable consequences.

C33 Process Analysis: Date____ Name__________________ Hr_ Copy and Explain using 1 paragraph each. Describe how each of these landforms contributes sediments to a beach: Cliff b. Hills c. River Describe advantages & disadvantages for: a. Dredge b. Jetty c. Breakwater d. Seawall