Geo Lab (CH. 14)
breaker zone
In the ______, wave base intersects the sea floor; here the waves lose symmetry and "break"
waves
_________ are the dominant force in shoreline erosion and deposition
embayments
coastal erosion is slowest in deep, low areas of coastal land called _________ where wave energy is diffused along a broad stretch of coastline
beaches, spits, barrier islands, salt marshes/tidal marshes
common shoreline depositional features include:
longshore drift
in areas where there is an abundant supply of unconsolidated sediment, longshore currents move sand and silt parallel to the shoreline in a process called ____________
hooks
spits that are curved sharply
salt marshes/tidal marshes
the area between a barrier island and the shoreline; formed by sediment derived from the mainland; these areas are covered with vegetation tolerant to salt water
seawalls, beach sand, groynes
3 expensive coastal management strategies: 1. building ______ to prevent wave erosion 2. renourishing eroded ________ 3. trapping sand moved by longshore drift with structures called _______
sea-level change, coastal storms, tsunamis
3 ways in which shorelines become potential natural disasters:
friction
Waves form by ____ generated when wind blows across the surface of an ocean or lake.
bench, notches
Waves move sediment back and forth across the tidal zone, abrading a flat wave-cut _____ and carving wave-cut ______
greater, smaller, lowering, raising
When an ocean widens or begins to close, the water must occupy the ______ or ______ volume of the ocean basin, _______ or _______ sea level along the ocean shoreline
shallower, break
When water is __________ than the wave base, orbiting water molecules interfere with the sea floor or lake bottom, causing waves to lose symmetry and "_____".
radius
Within a deep-ocean wave, water molecules move in a circular path. The ______ of the circle decreases with depth
tides
______ move enormous amounts of sediment all along the shoreline
emergent
______ shorelines are typically straight and bounded by steep cliffs
tsumanis
_______ are enormous waves generated by earthquakes or volcanic explosions in the ocean basins
shorelines
_______ are in a constant state of conflict between destructive wave erosion and the constructional processes of deposition, lava flows, and coral reef development
coastal erosion
_______ is most rapid in places where the land extends OUT into the ocean, because this position allows waves to attack the land from nearly every direction
Wind
_______ is not only responsible for driving waves; it also moves sediment directly in shoreline areas producing coastal sand dunes
sea arches, sea stacks
________ and ________ are distinctive, often dramatic bedrock landforms found close to the current shoreline, a short distance from the shore
tectonic activity
________ creates ocean basins, enlarges or shrinks them, and may uplift or lower the land along the coast
wind, storm surge
a common misconception about coastal storms is that _____ is the major hazard, but the _______, a wall of water driven onshore by the hurricane, is much more hazardous
wave-cut benches and wave-cut notches, sea arches and sea stacks
coastal erosion leads to 2 types of landforms to develop:
spits
elongate sand bars attached at one end to the mainland
barrier islands
elongate sand bars that lie offshore and are not connected to the mainland
submergent shorelines
if the land sinks or sea level rises, the shoreline appears to be drowned, with irregular coastline, prominent bays, and abundant islands, marshes, and lagoons
emergent shorelines
land appears to have risen from the sea by tectonic uplift or a drop in sea level
cliff retreat
sea stacks along a coastline mark the former position of the bedrock cliffs, letting us measure the amount of _______
marshy wetlands
sediment eroded from the mainland is deposited in bays between the shore and the barrier islands, forming ________
inland
shoreline cliffs gradually retreat _______
barrier islands, spits
shoreline currents redistribute sediment to produce __________, ______, and other landforms
groynes
structures that are built perpendicular to the shoreline in an attempt to trap moving sand and prevent its loss to downdrift areas
beaches
the most common depositional features and consist of sand (or coarser sediment, coral and shell fragments, etc.)
retrograde ellipse
the movement under wave bases caused by wind
breaks
the wave ______ on the shore when the ellipse can't complete its cycle once it hits land
sea stack
when further erosion removes the support for the arch, it will collapse and leave an isolated remnant of the bedrock called a _______
longshore drift
wind controls how loose materials will be moved along the shoreline in a process called ____________
sea arch
zones of weak bedrock may be eroded quickly, isolating stronger material and starting to cut into it as well. Eventually, a ________ forms
wave base
Offshore, water molecules move in circular paths, each molecule passing some energy on to those it contacts. Loss of energy in contacts limits the depth of wave action to approximately half of the wavelength, a depth referred to as the _______.
type of material present
The _______ is one of the most important factors in the effectiveness of erosional and depositional processes and therefore shoreline stability
Bay of Fundy
The ________ between the Canadian provinces Nova Scotia and New Brunswick has the highest tidal range
tides
The gravitational attraction of the Sun and Moon cause the ________: water rising and falling along the shore twice a day in most coastal areas
weather systems, strength, direction, frequency
The height and velocity of waves in a region are controlled by weather factors such as the types of ________, the _____ and _____ of winds, and the ______ of storms
material, weather, climate, climate change, tidal range, tectonic activity
The nature and rapidity of shoreline change are controlled by 4 factors: 1. _________ of which the shoreline is made 2. ________, wind, _________, and __________ 3. __________ 4. ___________
slumping, rockfall, retreats away
Eventually, the wave-cut notch undermines the cliff, causing _______ or _______, and the cliff _________ from the shoreline
long-term changes
Geologists group shorelines into 2 categories, based on how they respond to _________.
tectonic activity, climate change
long-term sea-level changes are caused by:
wave-cut bench, wave-cut notch
occurs along the shorelines; as waves drive loose sediment across shorelines underlain by bedrock, the sediment abrades a flat surface called a _________ and cuts into the base of bedrock cliffs to form a ___________
wider, landward
over long periods of time, wave-cut benches become ______ as the coastal cliffs retreat ______