Understanding Earth EXAM 3

UNI, Dr. Iqbal

What is A?

Trough

What is B? (pretend it extends down to the trough)

wave height (H)

What is C?

Crest

What is D?

wavelength (L)

What 2 formations does this picture show?

Bays and Headland

Oceanic waves

the transfer of energy from wind to water

What is needed to cause oceanic waves

strong consistent winds and a very large water body

Wavelength (L)

distance between crest to crest

Wave height (H)

from trough to crest

Perdiod (T)

time between when one crest hitting the shore and the next crest

Short period means what?

stronger waves

Wave equation

V= L/T

What does V in the wave equation represent?

velocity

What does the L in the wave equation represent

wavelength

What does T in the wave equation represent?

period

What is velocity measured in?

feet per second

How do you figure out how deep below the surface you need to go before you won’t feel the waves?

½ the wavelength deep will be calm

Breaker

as waves approach the shore (becoming shallower) they become too steep to support themselves and break in the surf zone

If the breaker is close to the shore, what does that do to the beach?

high erosion

Headland

an extension of land into the ocean

Wave refraction

a change in wave direction due to a change in depth, pointing towards the projecting part of the shore

Is a headland or a bay facing more erosion?

headland

Rip current

a current that drags water back out to sea because there is something above or below the water that it cannot easily move past

Longshore drift

wavy pattern left on the beach from movement of sand particles by swash and backswash

Swash

water going up on the beach

Backwash

water going back to the sea after washing up on beach

Longshore current

a zigzag pattern current caused by boundary between two different currents, parallel to the shoreline

What kind of bottom topography will cause breakers to be close to the shore?

steep and eroded

Moon Tide

the moon’s gravitational pull on Earth’s ocean water

Why are there two bulges of maximum pull?

centrifugal force, and one side of the Earth is unaffected by the moon’s pull (that side is less of a bulge and more like unaffected water)

How long is a solar day (don’t overthink this)

24 hours

How long is a lunar day

24 hours and 50 minutes

How often do we get a high tide?

12 hours and 25 minutes

Sun tide

the sun’s gravitational pull o Earth’s water

Which type of tide causes a larger bulge?

moon

When does the sun and moon tide happen at the same time?

during a new and full moon

What is it called when the sun and moon tide happen at the same?

spring tide

Neap tides

when the moon tide and sun tide do not happen at the same, sun cancels out some of the moon’s pull

At what phases of the moon do neap tides occur?

3rd quarter and 1st quarter

What is the lowest possible high tide?

a neap tide

Tidal flat

an area where water recedes from, but when the tide comes back in, it happens quickly

List the ocean features

tidal flat, tidal valley, stack, wavecut terrace, sea arch, spit, Atoll

Shoreline of erosion

a shoreline that faces high rates of erosion, often have stacks

Stacks

can show where the shoreline previously was, erosional

Wave cut terrace

where the water level used to be

Sea arch

a window through a rock, shows high erosional power

Spit

a hooked shaped sandbar, product of longshore drift, hook end is where the end of the current is, depositional feature

Is a tidal valley depositional or erosional?

erosional

Is a tidal flat depositional or erosional?

depositional

Tidal valley

valleys carved out by ocean water (not rivers)

Atoll

a ring shaped island or sandbar with water in the middle

Is an atoll depositional or erosional?

depositional

What can cause an atoll?

an underwater volcano or hotspot

Characteristics of wind

low viscosity and density, no confining channel, turbulent flow

Modes of sediment transport

suspended load, bed load, saltation load

Capacity

suspended + bed + saltation load

Competence

the largest type of mode of sediment transport

Erosional features of wind

deflation, desert pavement, sandblasting

Deflation

an area where wind has caused a slight dip in the landscape due to small particles being swept away

What is the most powerful depositional and erosional agent?

running water

Desert pavement

areas of clean gravel or pebbles from wind moving fine particles away

Sandblasting

creates ventifact, fast moving sand particles in the wind polish surfaces

Ventifact

a rock that has been polished by sandblasting, can show which direction the wind was moving

Depositional features of wind

sand dunes,

Preconditions that cause sand dunes

very wide open area, availability of sand, strong consistent winds, an obstacle

Do sand dunes grow indefinitely, why?

no, at some point the wind will start taking off the top of the dune

Are sand dunes in a fixed spot?

no, they shift as their volume increases

What kind of dune is this?

Barchan dune

What kind of dune is this?

Blowout

What kind of dune is this?

Longitudinal

What kind of dune is this?

Transverse

What kind of dune is this?

Star

What is this glacial feature?

U-shaped valley

What is this glacial feature?

Striation

What is this glacial feature?

Hanging valley

What is this glacial feature?

Cirque

What is this glacial feature?

Arete

What is this glacial feature?

Horn

What is this glacial feature?

Tarn

What is this glacial feature?

fjord