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FOR FURTHER ANALYSIS INVITATION TO INQUIRY

1. What are the significant similarities and differences between Frost Wedging
weathering and erosion?
Rocks undergo mechanical weathering as freezing water expands,
2. Speculate whether the continents will ever be weathered and eroded exerting pressure on both sides of a crack in a rock, making it slightly
flat, at sea level. Provide evidence to support your speculation.
larger. How much does water expand upon freezing? To investigate,
3. Is it possible for running water to erode below sea level? Provide pour water into a plastic cylinder, mark the water level, and place it in
evidence or some observation to support your answer. Is it possible
a freezer. How much did the ice expand?
for any agent of erosion to erode the land to below sea level?

PARALLEL EXERCISES

The exercises in groups A and B cover the same concepts. Solutions to group A exercises are located in appendix E.
Group A Group B
1. Frost wedging breaks apart a large rock measuring 10 m long by 1. Frost wedging breaks apart a large rock measuring 10 m long by
10 m wide by 2 m high into four equal pieces measuring 5 m 10 m wide by 2 m high into 32 equal pieces measuring 1 m high
2
2
long by 5 m wide by 2 m high. How much greater, in m , is the by 2.5 m wide by 2.5 m long. How much greater, in m , is the
total surface area of the four pieces compared to that of the total surface area of the 32 pieces compared to that of the
original rock? original rock?
2. In 2000, a class examined a graveyard with marble tombstones to 2. The average rate of chemical weathering of carbonate rock in an
−3
determine the average rate of chemical weathering of carbonate urban area is 2.1 × 10 mm/yr. The depth of lettering of the
rock. By measuring the depth of the lettering they determined tombstones shown in the table below was measured in 2010:
the weathering depth (surface reduction) on various tombstones
to be as shown in this table:
Date on Tombstone Age (yr)
Date on Tombstone Surface Reduction (mm) 1910 100
1921 89
1906 0.09 1948 62
1912 0.13 1958 52
1937 0.11 1975 35
1946 0.06
How much has the depth of the lettering been reduced on each
1955 0.02
tombstone?
What is the average rate of weathering of the tombstones?
3. During the Pleistocene, a large rock was moved 129 m down a 3. A slope is creeping at a rate of 1.2 mm/yr. A new tree is
gentle slope over a 2,260 year period via the process of creep. planted on this slope. How long will it take to displace this tree
What was the creep rate in cm/yr? by 7.5 cm?
4. A cemetery maintenance company is monitoring the 4. The maintenance department of a botanical garden is
displacement of tombstones that have moved by the process of monitoring the displacement of statues that have moved by the
creep. Tombstones must be straightened when the displacement process of creep. The statues must be straightened when the
reaches 20 cm to prevent toppling. By measuring the tilt angle on displacement reaches 15 cm to prevent toppling. By measuring
various tombstones, they determined the creep rate in 2010 to be the tilt angle on the statues, they determined the creep rate in
as shown in this table: 2005 to be as shown in this table:

Date on Tombstone Rate (mm/yr) Date Installed Rate (mm/yr)
1925 2.14 1933 2.01
1931 2.25 1957 2.35
1948 2.95 1963 3.1
1965 2.98 1976 2.69
1970 2.95 1985 2.5
Which tombstone will need to be straightened first? Which statue will need to be straightened first?

20-19 CHAPTER 20 Shaping Earth’s Surface 519