Download WEEK 17 – WIND AND WAVE EROSION

WEEK 17 – WIND AND WAVE EROSION
WIND EROSION
I.
Typically wind can only carry small sediment. However, hurricanes &
tornadoes can carry larger sediment.
II.
Characteristics of wind deposited sediments or wind abraded structures
a. Fine grained (small) deposits
b. Well sorted deposits
c. Sand dunes – asymmetrical shape. The wind comes from the side with the
gentle slope (the windward side). The side of the dune facing away from
the wind has a steeper slope (called the leeward side).
d. Frosted and pitted rocks – called ventifacts.
e. “Mushroom” shaped rocks
WAVE EROSION
I.
Waves are caused by Wind! The friction between the air and the sea surface
is what makes waves. The direction the wind is coming from is the direction
the waves will be coming from.
II.
When the waves strike a beach at an angle, a LONGSHORE CURRENT or
LONGSHORE DRIFT will arise.
a. Longshore current is the lateral (sideways) motion of sand along a beach.
Sediment follows a zig zag pattern.
b. Jetties are often built to stop the motion of the sand. A jetty is a barrier of
large boulders perpendicular to the shore line.
c. Sand bars and Spits are a common landforms created by wave action
along the shoreline. There are many spits on the N. Shore of Long Island
and around the LI Sound.
West Neck
Beaach
Cape Cod, MA
d. When the wave strike the coast directly, headland cliffs form.
e. Storms and wave action combine to create Barrier Islands. Barrier Islands
are large sandy islands that provide protection for coastal regions. Barrier
Islands are found all throughout the eastern coast of the US. Jones beach,
Long beach, Robert Moses beach, Fire Island are all great local examples
of barrier islands. They are basically really large sustained sand bars.
BARRIER ISLANDS