ERS 108 Exam 1 (2)

The rate of erosion of a seacliff is influenced by fracture density, tidal range, and wave energy. Fracture density refers to the number of cracks and fractures in the rock, which can weaken the cliff and make it more susceptible to erosion. Tidal range plays a role in erosion as the rise and fall of tides can impact the force and direction of waves hitting the cliff. Wave energy, determined by factors such as wind speed and fetch, also affects erosion by determining the power and intensity of the waves crashing against the cliff. Therefore, all of these factors contribute to the rate of erosion of a seacliff.

A landslide refers to the sudden and rapid movement of large amounts of material, such as rocks, soil, or debris, downhill. It is a geological term used to describe this phenomenon, which can be triggered by factors like heavy rainfall, earthquakes, or human activities. Landslides can cause significant damage to the surrounding environment, infrastructure, and pose a threat to human lives.

The upper delta begins where distributaries begin to branch from the main stem of the river. In a river delta, distributaries are smaller channels that split off from the main river and carry water and sediment to the surrounding area. The upper delta refers to the initial part of the delta where these distributaries first start to form and diverge from the main river channel. This is an important feature of a delta as it helps to distribute water and sediment across a wider area, contributing to the formation and growth of the delta landform.

The correct answer is "change over time as plates interact." This is because the movement of tectonic plates on Earth's surface causes the shorelines to change. As plates interact, they can create various geological features such as mountains, valleys, and rifts, which in turn affect the shape and position of shorelines. This process occurs over long periods of time, as the movement of plates is gradual. Therefore, the shorelines are not unchanging, but rather constantly evolving due to plate tectonics.

San Francisco Bay is an estuary formed by tectonic processes. The bay was created as a result of the movement of tectonic plates along the San Andreas Fault. The Pacific Plate is moving northwestward while the North American Plate is moving southeastward, causing the crust to crack and form a depression. This depression gradually filled with water from the Pacific Ocean, creating the estuary known as San Francisco Bay.

Hydraulic action refers to the force of water against the bedrock, causing it to break apart. This process is particularly effective in areas with strong waves or currents. Abrasion occurs when sediment carried by the water rubs against the bedrock, wearing it down over time. Dissolution happens when certain minerals in the bedrock dissolve in water, weakening the structure. These three processes, hydraulic action, abrasion, and dissolution, all contribute to the erosion of bedrock by the ocean.

The shape of a river delta is influenced by three factors: river input, waves, and tides. River input refers to the amount of sediment and water flowing into the delta from the river. Waves play a role in shaping the delta by eroding and depositing sediment along the coastline. Tides also contribute to the shape of the delta by affecting the movement of water and sediment in and out of the area. These three factors work together to determine the size, shape, and configuration of a river delta.

Sea cliffs and sea caves are both types of landforms found on the Maine coast. Sea cliffs are steep cliffs that are formed by the erosion of coastal rocks by the sea. They can be found along the shoreline and are often characterized by their vertical or near-vertical slopes. Sea caves, on the other hand, are hollowed-out spaces within the cliffs that are formed by the constant pounding of waves against the rock. These caves can vary in size and shape and provide unique habitats for marine life. So, both sea cliffs and sea caves are present on the Maine coast.

The correct answer is "very narrow." The comparison is between the coastal zone on the U.S. East Coast and the U.S. West Coast. The statement suggests that the coastal zone on the U.S. West Coast is narrower than the coastal zone on the U.S. East Coast.

The Mississippi River delta is losing land rapidly. This is because the river carries large amounts of sediment and deposits it at the mouth of the river, forming new land. However, human activities such as channelization and levee construction have disrupted the natural flow of sediment, causing the delta to erode and lose land. Additionally, factors like sea level rise and subsidence also contribute to the rapid land loss in the Mississippi River delta.

Rivers transport sediment through three main mechanisms: solution, suspension, and bedload. Solution refers to the process in which sediment is dissolved in the water and carried along with the flow. Suspension occurs when smaller particles are carried within the water column, remaining suspended due to the flow velocity. Bedload refers to larger particles that are transported by rolling, sliding, or bouncing along the riverbed. These three mechanisms collectively contribute to the movement and deposition of sediment in rivers.

Estuarine sediment ultimately comes from two main sources: rivers and bluffs. Rivers bring sediment from land, including soil erosion and weathering of rocks. Bluffs are cliffs or steep slopes along the shoreline that erode and contribute sediment to the estuary. Additionally, offshore biological sources, such as marine plants and animals, can also contribute organic matter and sediment to the estuary. Similarly, the continental shelf, which is the submerged part of a continent, can also provide sediment to the estuary through biological processes.

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Convergent boundary zones, specifically collisional ones, have the fewest large river deltas. In these settings, two tectonic plates collide, causing the uplift of land and the formation of mountains. This uplift inhibits the formation of large river deltas because the land is not subsiding or sinking, which is necessary for the creation of extensive delta systems. Therefore, collisional convergent boundary zones have the fewest large river deltas compared to other coastal tectonic settings.

Maine's trailing edge coast is rocky because it was glaciated. During the last ice age, glaciers covered the region and as they advanced and retreated, they scraped away the softer sedimentary rocks, leaving behind the harder igneous and metamorphic rocks that make up the rocky coastline of Maine. This process of glaciation resulted in the formation of the rocky terrain along the coast.

Under Maine's Shoreland Zoning Law, highly hazardous bluffs require that new houses be set back from their edge. This means that new houses cannot be built too close to the edge of the bluffs in order to minimize the risk of erosion and potential collapse. This setback requirement helps to ensure the safety and stability of the houses and the surrounding environment.

The destruction of New Orleans by storm surge was inevitable because the city is located below sea level and is surrounded by bodies of water, making it vulnerable to flooding. Additionally, the city's levee system was not designed to withstand a storm of that magnitude, further increasing the inevitability of the destruction. Despite efforts to improve the levee system after previous hurricanes, the combination of natural factors and human actions made the destruction of New Orleans by storm surge unavoidable.

Flooding is one mechanism by which deltas grow vertically as the deposition of sediment during flood events increases the height of the delta. Meandering refers to the lateral migration of the river channel, which leads to the accumulation of sediment on the inner bank, contributing to vertical growth. Peat formation occurs when organic material accumulates in swampy areas, and over time, it can contribute to the vertical growth of the delta as more sediment is added.

An autogenic landform refers to a landform that is primarily formed by internal processes within the Earth, such as erosion, weathering, and deposition. A salt marsh fits this description as it is formed by the accumulation of sediment and organic matter in coastal areas, resulting in the formation of a low-lying, marshy area. This process is mainly driven by the interaction of tides, waves, and the deposition of sediment, making a salt marsh an example of an autogenic landform.

River sediment rarely, if ever, escapes from estuaries because estuaries are typically characterized by low energy environments, where the flow of water is slow and there is limited wave action. As a result, the sediment carried by the river tends to settle and accumulate in the estuary rather than being transported further. This accumulation of sediment can lead to the filling of estuaries over time. Additionally, the lack of strong currents in estuaries prevents the sediment from being carried out to sea and building deltas on the continental shelf.

Asia has a very high sediment yield, which means that there is a significant amount of sediment being transported by rivers in this region. This high sediment yield leads to large river sediment discharges in Asia. This could be due to various factors such as high erosion rates, steep topography, and intense rainfall. The large river sediment discharges in Asia have important implications for the region's ecosystems, water quality, and infrastructure development.

Waves most effectively erode bedrock in areas with small tidal ranges. This is because in areas with small tidal ranges, the waves have a greater impact on the bedrock as they are not diluted or weakened by the incoming and outgoing tides. In contrast, in areas with large tidal ranges, the waves are spread out over a larger area and their erosive power is reduced. Therefore, areas with small tidal ranges experience more concentrated wave energy, leading to more effective erosion of the bedrock.

Sea cliff erosion is a societal problem in California because the state has a long coastline that is prone to erosion due to various factors such as wave action, coastal storms, and sea level rise. The cliffs along the California coast are made of soft sedimentary rocks that are easily eroded by these forces. This erosion not only threatens coastal infrastructure and properties but also impacts the natural environment and habitats. Therefore, California is a place where sea cliff erosion is a significant concern for society.

W. Morris Davis's 19th Century classification of coasts was based on the maturity of the shoreline. This means that he categorized coasts based on their level of development and evolution over time. The maturity of a shoreline refers to its stage of development, which can be influenced by factors such as erosion, sedimentation, and the presence of landforms like cliffs, beaches, and dunes. By studying the maturity of coastlines, Davis aimed to understand the processes and patterns of coastal evolution.

A shallow estuary with a large tidal range is likely to be well mixed because the large tidal range causes strong currents and mixing of water. This mixing prevents stratification, where layers of water with different properties (such as temperature or salinity) form. The rocky, relatively fresh, and none of these options are not necessarily related to the tidal range or mixing in the estuary.

Subsidence is the correct answer because it refers to the sinking or settling of the land, which is a crucial factor in the destruction of river deltas. As the land subsides, the delta becomes more vulnerable to erosion and flooding, leading to the loss of valuable wetland habitats and the disruption of ecosystems. Flooding, meandering, and crevasse splays are important processes in the formation and shaping of river deltas, but they do not directly contribute to their destruction.

The correct answer is "say nothing of armoring bluffs." This means that federal laws do not specifically address or regulate the practice of armoring bluffs. It suggests that there are no explicit regulations or guidelines regarding the use of protective structures or measures to prevent erosion or collapse of bluffs.

Accommodating bluff erosion usually means creating a new environment to slow erosion. This suggests that instead of trying to prevent erosion through building armoring or moving houses, the focus is on creating a different environment that can help slow down the erosion process. This could involve measures such as planting vegetation, constructing retaining walls, or implementing erosion control techniques to alter the natural conditions and reduce the impact of erosion on the bluffs.

The correct answer options for a homeowner on a rapidly eroding bluff to save their house are retreat, armor, and accommodate, or relocate. Retreat refers to moving away from the bluff and finding a safer location for the house. Armor involves implementing protective measures such as building seawalls or installing erosion control structures. Accommodate means adapting to the erosion by modifying the house or property to withstand the effects. Relocate refers to completely moving the house to a new location away from the eroding bluff.

Differential erosion refers to the process where various types of rocks erode at different rates. This means that certain rocks may be more resistant to erosion and will therefore erode at a slower pace compared to other rocks. The concept of differential erosion is important in understanding how landscapes are shaped and formed over time, as it helps explain the varying rates of erosion in different areas.