Laboratory Manual for Introductory Geology 4e

EXERCISE 17.9
Depositional Processes and Shoreline Landforms
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FIGURE 17.17 and FIGURE 17.18 are topographic maps of the northern end of Cape Cod made almost 100 years apart.
The terminal moraine that forms Cape Cod provides an abundant source of sand and gravel for shoreline processes. These
two maps help illustrate how much change can occur along a coastline in a (geologically) short period. They also show
how population pressures affect our use of limited, and therefore very valuable, shoreline space.
(a) What kind of landform is Long Point?
(b) Draw arrows on Figure 17.18 to indicate the direction of longshore currents in this area.
(c) Describe the geologic changes that have occurred in the century separating the compilation of these two maps.
(d) How have Cape Codders tried to prevent Provincetown Harbor from changing?
(e) Based on what happened in the 98 years recorded by these two maps, which landforms might disappear in the
future? Which might change shape drastically? Explain your reasoning.
(f) Which of these changes would be beneficial to people living or vacationing in Provincetown? Which would be
negative? How might the latter be prevented?
(g) Describe the anthropogenic changes (e.g., in transportation, housing, and other uses) that have affected this area
in the century separating the compilation of the two maps.
wetlands are often targets for commercial development, either for new housing in
desirable coastal areas or new shopping centers catering to residents. Asphalt and
concrete are neither porous nor permeable and cannot absorb water from storm
surge or coastal flooding. The result is increased damage to the areas from which
the natural defenses have been removed.
In Exercises 17.8 and 17.9, you will explore shoreline depositional environments
both in the present and in the past.
17.3 SHORELINE EROSION AND DEPOSITION
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