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136 Cards in this Set
- Front
- Back
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the zone that lies between the lowest tide level and the highest elevation on land that is affected by storm waves is called...
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the coast
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what marks the boundary between the coast and the shore?
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the coastline
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the ____ is above the high tide shoreline and is covered with water only during storms
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backshore
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the _____ is the zone between the low and high tide lines
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foreshore
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the _____ extends seaward from the low tide line to the low tide breaker line
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nearshore
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True or False: the nearshore is sometimes exposed to the atmosphere
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False
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the ____ zone is the zone deep enough that waves rarely affect the bottom
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offshore
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a ____ is a deposit of the shore area
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beach
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the area of the beach above the shoreline is called the_________
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recreational beach
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the ____ is the dry, gently sloping region at the foot of coastal cliffs or dunes
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berm
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what is the berm often composed of?
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sand
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the _____ _____ is the wet, sloping surface that extends from the berm to the shoreline
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beach face
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True or False: the low tide terrace and the beach face are synonymous
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True
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what are longshore bars?
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sand bars that parallel the shore offshore and are responsible for breaking waves
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what is the longshore trough?
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it separates the longshore bar from the beach face
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when beach sediment comes primarily from rivers that drain lowland areas, is the beach finer or coarser in texture?
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finer
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where can one find muddy coastlines?
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- coast of Suriname in S America
- Kerala coast of SW India |
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True or False: the S-ern Florida beach has a significant biologic component
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True
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what is the relationship between the particle size and beach slope?
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increasing size means a steeper beach slope
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what are the 2 types of movement along a beach?
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perpendicular and parallel to the shoreline
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using the terms swash and backwash, describe light wave activity
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much of the swash soaks into the beach, so backwash is reduced; causes a net movement of sand up the beach face
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using the terms swash and backwash, describe heavy wave activity
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the beach is saturated with water from the previous waves, so very little of the swash soaks into the beach and backwash dominates, causing a net movement of sand down the beach face
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during heavy wave activity, where does the sand from the berm go?
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to longshore bars
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how does a summertime beach differ from a wintertime beach/
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summertime- light wave activity produces a wide sandy berm and an overall steep beach face; reduced longshore bar
wintertime- heavy wave activity produces a narrow rocky berm and an overall flattened beach face; builds longshore bars |
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what causes waves to line up nearly parallel to the shore?
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refraction
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the zigzag fashion in which water moves along the shore creates a.....
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longshore current
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how fast are longshore currents?
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up to 4 km/hr
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True or False: Longshore currents are strong enough to move people off shore, carrying them far from where they initially entered the water
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True
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the movement of sediment in a zigzag fashion along the coast is called....
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longshore drift/transport
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True or False: the longshore current generally flows northward along both the Atlantic and Pacific shores of the US
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False; southward
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when beach sediment comes primarily from rivers that drain lowland areas, is the beach finer or coarser in texture?
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finer
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where can one find muddy coastlines?
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- coast of Suriname in S America
- Kerala coast of SW India |
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True or False: the S-ern Florida beach has a significant biologic component
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True
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what is the relationship between the particle size and beach slope?
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increasing size means a steeper beach slope
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what are the 2 types of movement along a beach?
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perpendicular and parallel to the shoreline
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using the terms swash and backwash, describe light wave activity
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much of the swash soaks into the beach, so backwash is reduced; causes a net movement of sand up the beach face
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using the terms swash and backwash, describe heavy wave activity
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the beach is saturated with water from the previous waves, so very little of the swash soaks into the beach and backwash dominates, causing a net movement of sand down the beach face
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during heavy wave activity, where does the sand from the berm go?
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to longshore bars
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how does a summertime beach differ from a wintertime beach/
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summertime- light wave activity produces a wide sandy berm and an overall steep beach face; reduced longshore bar
wintertime- heavy wave activity produces a narrow rocky berm and an overall flattened beach face; builds longshore bars |
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what causes waves to line up nearly parallel to the shore?
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refraction
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the zigzag fashion in which water moves along the shore creates a.....
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longshore current
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how fast are longshore currents?
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up to 4 km/hr
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True or False: Longshore currents are strong enough to move people off shore, carrying them far from where they initially entered the water
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True
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the movement of sediment in a zigzag fashion along the coast is called....
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longshore drift/transport
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True or False: the longshore current generally flows northward along both the Atlantic and Pacific shores of the US
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False; southward
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what are erosional type shores characterized by?
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headlands, wave-cut cliffs, sea caves, sea arches, sea stacks, and marine terraces
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what are depositional shores characterized by?
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beaches, spits, bay barriers, tombolos, barrier islands, deltas, and beach compartments
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when does beach starvation occur?
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when the sand supply is interrupted?
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what is beach replenishment?
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an expensive and temporary way to reduce beach starvation
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what's the difference between primary and secondary coasts?
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primary- developed by nonmarine activity
secondary- developed by marine activity |
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what are some examples of primary and secondary coasts?
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primary- land erosion coasts, subaerial deposition coasts, glacial deposition coasts, volcanic deposition coasts,
secondary- wave erosion coasts, marine deposition coasts, coasts formed by marine biological activity |
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what do ancient wave cut cliffs and stranded beaches above the present shoreline indicate about sea level?
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a drop in sea level relative to land
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what do old drowned beaches, sumberged dunes, wave cut cliffs, and drowned river vallyes indicate about sea level?
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a rise in sea level relative to land
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melting of continental ice caps during the past 18k years has resulted in a sea level rise of how many meters?
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120 m
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at what rate is sea level rising along the atlantic coast? gulf coast?
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.3 m/century for both
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how fast is the Mississippi River Delta eroding? how fast is erosion along the pacific coast?
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4.2 m/yr; 0.005 m/yr
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what controls the rate of wave erosion
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1. more shore exposed to ocean
2. decrease in tidal range 3. weakening of bedrock |
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why are groins built? why are jetties built?
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to trap sand; to protect harbor entrances
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why are breakwaters formed?
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to trap sand behind a structure
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what is a disadvantage of building breakwaters?
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they cause erosion downstream
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what is a disadvantage of building seawalls?
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cause loss of the recreational beach
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True or False: rip tides are related to the tides
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false
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what is an undertow
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a flow of water away from shore
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how wide are rip currents and how fast do they flow?
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15-45 m; 7-8 km/hr
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how can rip currents be recognized?
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by the way the interfere w/ incoming waves, brown color cuased by suspended sediment, foamy and choppy surface
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____% of all resuces by lifeguards involve people who are trapped in rip currents
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80
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what is the best way to escape a rip current?
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swim parallel to the shore and ride the waves in toward the beach; never swim directly against a rip current
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give examples of erosional type shores
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US Pacific Coast
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give examples of depositional type shores
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US SE Atlantic coast and Gulf of Mexico
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what is a marine terrace?
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a wave cut bench that is uplifted above sea level
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eroded material is carried away from ______ areas and deposited at ______ areas
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high energy; low energy
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what is a spit?
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a linear ridge of sediment that extends in the direction of longshore drift drom land into the deeper water near the mouth of a bay
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why is the end of a spit normally curved?
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due to the movement of currents
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if a spit extends across the bay and connects to the mainland, it will be called a....
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bay barrier, or a bay-mouth bar
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what is a tombolo?
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a sand ridge that connects and island or sea stack to the mainland; also connects 2 adjacent islands
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why are barrier islands important?
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they form a first line of defense against storm waves that would otherwise severely damage the shore
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when are most barrier islands believed to have develop?
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during the rise in sea level that began w/ melting of most recent major glacier some 18k yrs ago
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about how many barrier islands are there along the gulf and atlantic coasts of the US?
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> 280
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what separates a barrier island from the mainland?
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a lagoon
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give examples of notable barrier islands
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1. Fire Island off NY's coast
2. N Carolina's Outer Banks 3. Padre Island off Texas coast |
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from the ocean landward, what are typical physiographic features of barrier islands?
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1. ocean beach
2. dunes 3. barrier flat 4. hight salt marsh 5. low salt marsh 6. lagoon btwn island and mainland |
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why are dunes important to barrier islands?
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they prevent the lagoon against excessive flooding during storm drive high tides
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how does a barrier flat form?
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it forms behind the dunes from sand driven through the passes during storms
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which part of the salt marsh is more biologically productive: low salt marsh or high salt marsh?
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low salt marsh
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what happens to barrier islands as sea level rises?
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they migrate landward
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how are peat deposits formed?
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by the accumulation of organic matter in marsh environments. they provide evidence for barrier island migration
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what is a delta?
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sediment deposits at river mouths
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the Nile River Delta in Egypt is ________ because.....
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eroding; sediment is traped behind the Aswan High Dam
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what are the 3 components of a beach compartment?
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1. a series of rivers that supply sand 2 da beach
2. the beach itself where sand is moving 3. offshore submarine canyons where sand is drained away from da beach |
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what happens when a dam is built along one of the rivers that feed into the beach compartment?
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it deprives the beach of sand
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the average cost of sand used to replenish beaches is btwn ___ and ____ per .76 cubic meter
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5-10 $s; repleneshing the entire beach may cost hundreds of thousands to millions of dollars each year
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who is considered as the father of marine geology?
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Francis Shepard, who was one of the first to study coastal processes
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drowned river valleys are characterisitc of what type of shoreline?
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submerging shorelines
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stranded beach deposits are characteristic of what type of shoreline?
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emerging shoreline
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what is happening to the coasts of northern Asia, Europe, and N America?
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they are isostatically rebounding because glaciers have melted during the past 18k years
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tectonic and isostatic changes are limited to _______ while a change in sea water volume or ocean basin capacity results in......
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a segment of a continent's shoreline; worldwide change in sealevel
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how do the formation and destruction of inland lakes, and sea floor spreading rates influence eustatic changes in sea level?
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formation of large inland lakes results in a decrease in sea level, while destruction results in rise.
fast spreading raises sea level whereas slower spreading lowers sea level worldwide |
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how do ice ages cause eustatic sea level change?
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glaciers trap water that would otherwise be in ocean basins, lowering the sea level
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how long ago was the Pleistocene Epoch (give a time range)?
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1.6 million to 10K years ago
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describe sea level during the Pleistocene
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it fluctuated widely, but was at least 120 m below the present shoreline
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if ALL the remaining glacial ice on earth were to melt, sea level would rise.....
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at least 60 m
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how do changes in ocean temperature change sea level?
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cooler seawater contracts, lowering sea level and warmer seawater expands, raising sea level.
For every 1 degree (C) change, sea level changes 2 m |
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Are most coastal areas showing evidence of submergence or emergence?
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both
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CO2 in the atmosphere has increased by what % over the last 200 yrs? how much has the temperature risen over the past 130 yrs? how much as sea level risen over the past 100 yrs?
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30% and 0.6 deg Celcius and 10-25 cm
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By the year 2100, by how much will sea level rise (compared to today?
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1 m
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what percent of the world's sandy beaches are eroding?
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70%
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bedrock for most of Florida is a resistant type of sedimentary rock called _____. Most of bedrock northward through New Jersey consists of.....
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limestone; non-resistant sedimentary rocks
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what are Long Island and Cape Cod examples of?
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glacial deposits called moraines left behind when glaciers melted
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is the Atlantic US coast eroding or depositing?
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eroding
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Chesapeake Bay is an example of what sumberging coastal feature?
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drowned river valley
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what is happening to most of the US gulf coast?
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it is eroding. Louisiana has lost 1 million acres of delta and is also losing marshland
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which has the greater erosion rate: the Gulf coast or the Atlantic coast? (of the US)
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the Gulf Coast
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what is happening to the US pacific coast?
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it experiences less erosion that Gulf and Atlantic coasts. it is exposed to large ocean waves, so it loses sand in the winter, but regains it in the summer. it has relatively soft rocks
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of the Pacific states, what is the only state that shows a net sediment deposition?
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Washington
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what is hard stabilization?
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strucutres built to protect a coast from erosion or to prevent the movement of sand along the beach
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what are groins? what are they made of?
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they're built perpendicular to the shoreline and trap sand moving along the shore in longshore transport. they're made of a large blocky material called rip-rap and oftentimes, sturdy wood pilings
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what are jetties? how are they similar and different to groins?
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they're built perpendicular to the shore and constructed out of rip-rap, like groins. they are built primarily to protect harbor entrances in closely spaced pairs. they can cause more pronounced upstream deposition and downstream erosion that groins
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what are breakwaters?
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structures built parallel to shoreline, such as in Santa Barbara Harbor in California. they trap sand on one side and cause erosion on the other side.
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what are seawalls? what happens when they are constructed?
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a type of hard stabilization built parallel to the shoreline. turbulence generated by the abrupt release of wave energy erodes the sediment on the seawall's seaward side, causing it to collapse into the surf, which leads to loss of the recreational beach
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how much did it cost to move the cape hatteras lighthouse? how far was it moved from the shore? for how much longer is it expected to be safe from erosion?
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$12 million. 488 m. at least 100 yrs
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In general, the sand on most beaches comes from....
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rivers
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A berm is....
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a generally flat, sandy, wave-deposited feature. It is not affected by constant wetting from the tides or the effect of waves except during storms.
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True or False? Beach nourishment is the establishment of coastal structures that prevent the movement of sand downstream.
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False
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Where does most of the sand involved in longshore transport in beach compartments eventually end up?
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down submarine canyons
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Which longshore drift management technique was implemented at Santa Monica, California, before the breakwater was destroyed?
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Sand was dredged from behind (inshore of) the breakwater. By dredging the sand and placing it further down the coast, the energy required to move the sand behind the breakwater was put replaced by the electricity needed to run the dredge.
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What is the typical range for the point where the seafloor reaches a depth at which sediment is no longer disturbed by waves?
W) 10-20 cm X) 1-2 m Y) 10-20 m Z) 30-50 m |
Y
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At the landward edge of the low-tide terrace (the high-tide line), there is often an abrupt vertical face of sand, usually a few centimeters high, before the beach slopes normally upward again as dry backshore. This feature is called a________.
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scarp
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Wave erosion on steep coastlines can create _______________.
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cliffs
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True or FAlse: Sea level changes isostatically if the volume of water in the oceans changes or the volume of the ocean basins themselves changes.
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False
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True or False: Over half of the U.S. population lives in coastal counties.
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True
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how long is the great barrier reef?
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2000 km
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what are tidal wetlands?
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flat muddy areas covered by water during only part of the tidal cycle
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in what latitudes do mangroves grow best?
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between 30 deg N and S
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how are wetlands created?
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by the accumulatoin of sedimens from a variety of sources, most importantly organic detritus
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what are the 2 major deltas in the US?
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Mississippi delta and San Francisco Bay Delta
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what are levees?
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banks that are built along each side of the river channels to reduce flooding in deltas
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