Earth Science Mrs. Cavanagh
Name___________________________________
Lab- Rock Weathering
Purpose- You will observe different examples of rock weathering.
Central Ideas in Rock Weathering:
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Rocks or parts of rocks that have undergone physical weathering are more rounded.
Rocks or parts of rocks that have undergone physical weathering are smaller, worn away, or reduced in size.
Parts of rocks that have undergone physical weathering are lower or deeper within the rock compared to other
parts of the rock because the weathered part has worn away. Parts of the rock that are sticking up or are higher
(like bumps) have NOT been weathered as much.
Rocks or parts of rocks that have undergone chemical weathering often have a color change, especially if iron is
involved, in which case rock that was originally gray turns rusty brown.
MORE RESISTANT = less changed by weathering
LESS RESISTANT= more changed by weathering
VEIN in a rock= thin strip of one mineral running through or on surface of rock
Directions- There are 20 earth materials you will observe. For each material, there is a MULTIPLE CHOICE question to
answer. These questions are below in numerical order. Put the answer in the blank.
_____1. This rock has most clearly undergone what type of weathering: 1] Chemical
_____2. What part of the rock has been weathered more?
2] Physical
3] Mechanical
1] the INSIDE 2] The OUTSIDE
_____3. Which part of this rock has weathered more?
1] the LIGHT colored veins 2] the DARK parts
_____4. Which part of this rock has weathered more?
1] the LIGHT parts
_____5. Which part of this rock has weathered more?
1] the thin veins
2] the DARK parts
2] the rest of the rock
______6. Which part of the vein in this rock appears to have weathered more than the other part?
1]the part NEAR the number
2] the part AWAY from the number
_____7. There are three different colors labeled on this rock. Which letter marks the MOST weathered part of the rock?
_____8. Which part of the rock has weathered more?
1] the BUMPS on the top
2] the REST of the rock
_____ _____ _____ _____ _____ 9. Put the 5 rocks in order from the one that has been least weathered to the one
that has been most weathered.
_____10. Frost action would most affect which part of this rock?
rock
1] the CRACK, making it widen 2] the REST of the
_____ 11. The brown chemical weathering product all over this rock shows that what metal was present in the
unweathered rock?
1] iron
2] sodium
_____ 12. Which part of this rock has weathered more?
1] the DARK part
2] the LIGHT part
_____13. Which part of this rock has weathered more? 1] the GRAY crystals
2] the SURROUNDING ROCK
_____14. What causes this rock to become so rounded and smooth?
1] ABRASION against other rocks or sediments over time
2] WATER pounding on it over time
______15. The rock has fossil shell impressions (circled). What might happen to the rock over time if left in a stream?
1] abrasion might cause the rock to weather away, making the impressions not so clear
2] the rock might gain more shell impressions
_____16. This rock has fossil shell impressions that stand up higher than the surrounding rock. What has weathered
more over time? 1] the SHELL impressions
2] the REST of the rock
_____17. Place a drop of acid on the rocks. One should bubble, evidence of chemical weathering. The oine that bubbles
is limestone, which contains calcite. Which rock has the calcite in it? 1] A
2] B
_____18. Which part of the rock has weathered more? 1]the LINES sticking up 2] the REST of the rock
_____19. Soil is a mixture of weathered rock and organic matter. The more organic material, the darker the soil. Which
jat contains the most organic material? 1] A
2] B
_____ _____20. Match the rock pieces with their original parent rock.
_____ ______
QUESTIONS: Put all answers in the blanks on the side.
1. The cross section below shows a soil profile.
This soil was formed primarily by
(1) erosion by glaciers
(2) erosion by running water
(3) capillarity and human activity
(4) weathering and biological activity
Answers:
1.
2.
3.
4.
5.
6.
7.
8.
9.
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2. Which event is an example of chemical weathering?
(1) rocks falling off the face of a steep cliff
(2) feldspar in granite being crushed into clay sized particles
(3) water freezing in cracks in a roadside outcrop
(4) acid rain reacting with limestone bedrock
3. Which factor has the least effect on the weathering of a rock?
1) composition of the rock
2) exposure of the rock to the atmosphere
3) the number of fossils found in the rock
4) climatic conditions
4. ) A large rock is broken into several smaller pieces. Compared to the rate of weathering of the large rock, the rate of
weathering of the smaller pieces is
1) the same
2) less
3) greater
5. The table below shows the results of an investigation of four different types of rocks, weathering over a period of 30
minutes. Equal masses of similar-sized samples of rocks A, B, C, and D were placed in identical containers half-filled with
water. Each container was shaken uniformly for 5 minutes and the remaining samples of rocks were removed from the
water. Their masses were determined and recorded in the data table. The remaining samples of rocks were put back
into the containers half-filled with water and the procedure was repeated five times.
After 20 minutes, the rate of abrasion decreased for all rock samples. A major factor that explains this is the
1) hardening of the minerals
2) smoothing of the rock samples
3) sharpening of the edges of the rock samples
4) compacting of the rock samples
6. Which is the best example of physical weathering?
1) the cracking of rock caused by the freezing and thawing of water
2) the transportation of sediment in a stream
3) the reaction of limestone with acid rainwater
4) the formation of a sandbar along the side of a stream
7. The diagram below represents a sedimentary rock outcrop. Which rock layer is the most resistant to weathering?
1) 1
3) 2
2) 4
4) 3
8. & 9. The diagram below represents the dominant type of weathering for various climatic conditions.
8. Why is no frost action shown for locations with a mean annual temperature greater than 13DC?
1) Large amounts of precipitation fall at these locations.
2) Large amounts of evaporation takes place at these locations.
3) Very little freezing takes place in these locations.
4) Very little precipitation falls at these locations.
9) There is no particular type of weathering or frost action given for the temperature and precipitation values at the
location represented by the letter X. Why is this the case?
1) Only chemical weathering would occur under these conditions.
2) These conditions create both strong frost action and strong chemical weathering.
3) Only frost action would occur under these conditions.
4)No place on earth has these combinations of temperature and precipitation.