World Geo 3200/3202November 2010

IntroductionIn this lesson you will: 1.5.2 Define the terms sea cave, sea arch,

and stack. (k) 1.5.3 Explain how sea caves, sea arches and

stacks are formed. (a) 1.5.4 Analyze the processes that result in the

“straightening out” of an irregular coastline. (a)

Evolution of Sea StacksSea stacks are columns of land standing in

the ocean just off shore (many have plant growth on top)

Very common in eastern Canada. They are created over a long period of time

after a series of other land structures have eroded away.

Evolution of Sea StacksFirst sea caves are formed in a headland. Continued erosion turns sea caves in to the second

land feature, sea arches. Sea arches are an interesting sight too and have

drawn many tourists to the northern Peninsula of Newfoundland.

Erosion and eventual collapse of the arch top leaves a sea stack standing in the ocean.  

Figure 3.11 on pages 49-49 shows this evolution from three different points of reference. You must look at this figure it will help cement the concepts in your mind.

Sea CaveSea Cave Formation: "a"

in figure 3.11 on page 48 waves strike the headland

first; waves refract around the

headland and put hydraulic pressure on both sides of the headland;

erosion of the weak portions create caves and blow holes in the sides of the headland.

Sea ArchesSea Arch Formation : "b" in figure 3.11 on

page 48 eventually sea caves, on alternate sides of the

headland get deeper until they connect inside the headland forming a complete passage way or tunnel or “arch” through the head land.

Sea StackSea Stack Formation: "c"

in figure 3.11 on page 48 continuous erosion, of sea

arches, causes the collapse of the ground over the arch;

this leaves a pillar or column or “STACK” of land standing alone where the headland was.

Look Familiar????

Straightening of Emerging CoastlinesEmerging coastlines straighten in much the

same fashion as submerging coastlines; Erosion of headlands creates sea caves, sea

arches and sea stacks instead of bay beaches, spits and bay bars;

However, the result is similar in that headlands are reduced in size which straightens the coastline.

Compare the headland length in figure 3.11 before and after erosion.

Case Study

Human Adaptations to Land & Water FormsOutport

Newfoundland fishing villages built on rocky coastline

Stilt houses in Bangladesh show how humans have adapted living in deltas

Human Adaptations to Land & Water Forms

The Chunnel connecting England with France

Canadian railway construction through the Rocky Mountains

Case StudyAssigned Readings"Storm surges in Bangladesh" on p. 50-51 in

your text book.