Q-1. From the introduction of the paper, contrast the classification approach presented herein to some
of the previous approaches that (the authors claim) have fallen short.
Answer: Previously the coastal classification was based on genetic, purely descriptive, and combining of
these two approaches. But the complexity of coastal development and the limitation of information given
in the genetic approach makes it very limited for use. On the other hand, the diverse feature of the coast
with the resulting prolixity in terminology made the descriptive classification difficult to apply. Considering
the shortcoming of previous classifications, a new technique has been developed by considering plate
tectonics and global tectonics.
Q-2. From the section on Coastal Zone Dimensions, the authors propose that first-order features of
coasts have characteristic length scales associated with each of their three dimensions. What are the
three dimensions and the associated length scales with each dimension?
Answer:
1.
2.
3.
Dimensions
Linear dimensions along the coastline
On-off shore dimensions, including the continental shelves and the
coastal plains
Vertical dimensions from the ocean floor to the summits of coastal
mountains
Length scale
≈1000 km
≈ 100 km
≈ 10 km
Q-3. From the section on Tectonic Classification: First-Order Features, using the terminology of the
authors, identify the three general "classes" into which the world's coasts can be categorized.
Answer: First-Order Features consists of three classes into which the world’s coast can be categorized:
(i)Collision edge coast, (ii) Trailing edge coast, and (iii) Marginal Sea coast.
Q-4. Also in the section on Tectonic Classification: First-Order Features, the authors claim that the
character of a trailing edge coast is strongly affected by what is happening (and has happened) on the
opposite edge of the continent. Elaborate on this idea, by explaining what should be expected along a
trailing edge coast that is opposing a coast (on the other side of the continent) that is a collisional leading
edge?
Answer: What happens on the continent's collisional leading edge has a big impact on the part of the coast
at the continent's trailing edge. If the continents leading-edge collides with another plate, the existence of
steep mountains leads the continent's trailing-edge side to have a larger drainage area. As a result, along
the trailing edge of the colliding continent, river (stream) erosion becomes high, which leads to a large
amount of sediments. Because of this huge sediment load, these beaches can form vast continental shelves
and may have extensive barrier island systems.
Q-5. Sticking with this concept, explain what should be expected (comparatively) along a trailing edge
coast that is opposing a coast (on the other side of the continent) that is another trailing edge?
Answer: Where a trailing edge coast has another trailing edge on the opposite side of the same continent,
the potential for coastal modification by terrestrial erosion and deposition is low. As there is no significant
elevated sedimentary source topography whose erosional products might contribute a sediment load to
enhance the coastal environment's dynamics.
Q-6. An example that illustrates the point made by the previous two questions is the ranking of world
rivers. Please provide the world ranks of the Congo, Nile, Amazon, and Mississippi rivers in drainage area
and sediment load. Comment on the rankings in light of your answer to the previous two questions.
Answer: The world ranks of the Congo, Nile, Amazon, Mississippi rivers are 2, 4, 1, 3 and 21, 15, 3, 6 based
on the drainage area and sediment load, respectively. Here the Amazon and Mississippi rivers are located
at the trailing edge of the collision coast, which brings lots of sediments to the river, as a result, they stand
first and third in drainage area and third and sixth, respectively in sediment load. On the other side, the
Congo and Nile rivers are situated on the trailing edge coast that is opposing another trailing edge coast,
which has less potential of terrestrial erosion, that’s why though they rank second and fourth in the size of
drainage area but rank only twenty-first and fifteenth, in the amount of sediment load.
Q-7. Using the worldwide distribution of tectonic coastal types, provided in Figure 4, give an example of
each of the following: a Continental collisional coast, an Island arc collisional coast, a Neo-trailing-edge
coast, an Afro-trailing-edge coast, an Amero-trailing-edge coast, and Marginal sea coast.
Answer:
Tectonic coastal types
Continental collisional coast
Island arc collisional coast
Neo-trailing-edge coast
Afro-trailing-edge coast
Amero-trailing-edge coast
Marginal sea coast
Example
West coast of South America
Aleutian Islands
Gulf of California
West coast of Africa
East coast of North America
Vietnam