1. Three factors that determine the height, length, and period of a wave are wind speed, length of time the wind has blown, and fetch (the distance that the wind has traveled across the open water).
2. The motion of a water particle as a wave passes is a circular orbit followed by the water particles at the surface with a diameter equal t the wave height. As a wave passes, a water particle returns almost to its original position.
3. When a wave approaches the shore the water becomes shallower and influences wave behavior. The wave begins to feel bottom at a water depth equal t about one-half its wave height. At this depth it interferes the water movement at the base slowing it down. As it continues to advance toward the shore, the slightly faster seaward waves catch up, decreasing the wave length. As the speed and length of the wave decrease, it steadily grows higher. When the steep wave front is unable to support the wave it breaks. After a wave brakes, the wave or oscillation becomes a wave of translation in which the water advances up the shore. The turbulent water created by breaking waves is called surf.
4. Two ways in which waves cause erosion are by wave impact and pressure, and by abrasion or the sawing and grinding action of the water armed with rock fragments. Wave impact and pressure do most f their work during storms. Cracks and crevices are quickly opened in cliffs, seawalls, breakwaters, etc. Water is forced into every opening, causing air in the cracks to compress by the thrust s crashing waves. Once the wave subsides the air expands rapidly, and dislodges rock fragments.
5. Wave refraction is the bending f waves. The effect of this process along irregular coastlines is due to wave refraction, the greatest erosional power is concentrated on the headlands. In the bays, the forces of the waves is much weaker. This causes the irregular coastlines.
6. Beaches are often called "rivers of sand" because at any point along a beach there is likely to be more sediment that was derived elsewhere than material eroded from the cliff immediately behind it. In many areas sediment-laden rivers that discharge into the ocean are the major source of material. If it were not for beach drift and longshore currents, many beaches would be nearly sandless.
7. Wave-cut cliff originate by the cutting action of the surf against the base of coastal land. Wave-cut platforms form as erosion progresses after a wave-cut cliff is formed, rocks overhanging the notch at the base of the cliff retreats. Left behind by the receding cliff is a relatively flat, bench-like surface is the wave-cut platform. Headlands that extend into the sea are vigorously being attacked by the waves because of refraction causing erosion. The surf erodes the softer or more highly fractured rock first. First, sea caves may form, then when two caves unite on opposite sides of the headland unite a sea arch results. A sea stack is an isolated remnant of the arch after it falls in on the wave-cut platform. Spits are elongated ridges of sand that are formed by longshore drift. A baymouth bar is a sand bar that completely crosses a bay which tends to form in weak currents where spits extend to the other side. It forms where longshore drift of sediment over powers currents flowing into and out of the bay. A tombolo is a ridge of sand that connects an island to mainland or another island which is formed in the same way as a spit.
8. Three possible ways in which barrier islands originate are they are thought to have originated as spits that were subsequently severed from the mainland by wave erosion or by the general rise in sea level following the last episode of glaciation, created when turbulent waters in the line of breakers heap up sand that has been scoured from the bottom, and may be former sand dune ridges that originated along the shore during the last glacial period, when sea level rose.
9. A groin is built to maintain or widen beaches that are losing sand. A grin is a barrier built at a right angle to the beach for the purpose of trapping sand that is moving parallel to the shore. The building of one groin might lead to the building of others because the groin is so efficient that the long shore current beyond the groin is sand deficient. The current removes sand from the beach on the leeward side of the groin. Other groins are built to offset this situation.
10. The building of jetties at Ocean City, Maryland, affected the areas north and south of the inlet by a wide beach at Ocean City, north of the jetty was formed and at Assateague Island, south of the jetty, has been starved of sediments.
11. A seawall might lead t increased beach erosion by the seawall cuts off the process of waves expanding much of their energy as they move across an open beach by reflecting the force of unspent waves seaward.
12. The most acceptable combat to beach erosion is beach nourishment. Two drawbacks of this method are that it is costly and can lead to unwanted environment effects.
13. The basis for the predictions that global air temperatures will rise is the fact that the carbon dioxide content of the atmosphere has been rising at an accelerating rate for more than a half a century. A warmer atmosphere can lead to a rise in sea level by higher temperatures can cause glacial ice to melt and a warmer atmosphere causes an increases in ocean volume through thermal expansion.
14. The bulk of the sand on many beaches in Western United States are supplied by rivers that transport it from the mountainous regions to the east. Due to damming, the sand that nourishes the beaches is trapped, causing the shrinking of beaches. Narrower beaches lead to accelerated sea cliff retreat because when the beaches were wider, they served to protect the cliffs from the face f the waves.
15. The observable features that would lead you to classify a coastal area as emergent are wave-cut cliffs and platforms.
16. Estuaries are associated with submergent coasts because the shoreline of a coast that has been submerged is highly irregular because the sea typically floods the lower reaches f the river valleys flowing into the oceans. The ridges separating the valley remaining upland, projecting into the sea like headlands. Drowned river mouths are estuaries.
17. The origin of ocean tides is it results from the gravitational attraction exerted upon the Earth by the moon, and to a lesser extent by the Sun. The moon’s gravitational force can cause the water to bulge on the side of the Earth nearest the moon.
18. An observer can experience two unequal high tides during one day because depending upon the moon’s position, the tidal bulges may be inclined to the equator. The first high tide experienced by an observer in the Northern Hemisphere is considerably lower the high tide half a day later. An observer in the Southern Hemisphere would experience the opposite effect.
19. The Sun influences tides by near the times of new and full moons, the Sun and moon are aligned and their forces are added together. The two tide producing bodies cause higher high tides and lower low tides. These are the spring tides. During the first and third quarters of the moon and the Sun are at right angles resulting in a smaller range f tides (neap tides).
20. Flood currents submerge the low-lying coastal zone and ebb currents expose the drowned portion of the shore.
21. Tides have affected the Earth’s rotation by the fraction against the floor of the ocean basins act as weak breaks that are steadily slowing the Earth’s rotation. Geologists substantiate this idea by the microscopic examination of shells of certain invertebrates. Clams and corals grow a microscopically thin layer f new shell material per day. By studying the daily growth rings of some well preserved fossil specimens, you can find the number of days in a year. Astronomers measure the length of day to be increasing 0.002 seconds per century.