Road Cut Geology Web Quest
Name _______________________________
Background Information: Read the summary and answer the #1-4 questions below.
Summary:
Roadcuts are the geologist's best friend. Look at the tilted slate in figure 1.
The rocks are exposed in detail in the roadcut whereas only a few stone spikes of rock
crop out of the hillside above it. Without a road cut to expose the rocks, most of them
would be hidden under vegetation. The widespread development of modern roads has been
great for students of geology because it allowed them to see the rocks easily.
Soil and vegetation cover most rock structures, especially the softer rocks.
However, natural outcrops of harder rocks are found in stream beds, cliffs of various
kinds, caverns and heavily eroded terrain. Natural outcrops are usually weathered, making
it difficult to see the true character
There's a reason why geology arose along with industrial technology. William Smith
could create his geologic map of 1815, (See Figure 2) the world's first, only because his
business was digging canals everywhere in Great Britain. The rise of canals, railroads and
paved roads cut open the landscape like a knife, making mapping much easier. When you can
study one perfect roadside exposure, you can recognize the rock elsewhere even when only
bits and pieces stick above the soil.
1. Why are roadcuts a geologist’s
best friend?
2. What are natural outcrops?
3. Why is geology difficult to
study without roadcuts and
natural outcrops?
4. What is the reason we learned
so much more about geology
with the industrial revolution?
Part 2. For each numbered photo, identify if it is showing mainly metamorphic,
igneous or sedimentary rock and write the observation or observations that are the
evidence you used. Use M, I, or S. You may see the color version of the photos by
clicking on the handout on the class website. .
Part 3. Answer the Analysis Questions at the end of the webquest. (Write on the
handout)
Figure 1.
Rock type ____ evidence____________________________________
Figure 2 Geology Bedrock map
Figure 3
Rock type ____ evidence___________________________________________
Figure 4. Rock type ____ evidence___________________________________________
Dikes are shown in Figure 4.
Figure 5. Rock type ____ evidence___________________________________________
Folded rock layers are shown in Figure 5.
Figure 6a. figure 6a shows a diagram of the difference between a dike and a sill. They are
both formed from liquid magma that cools underground. Label the real dike and sills in the
photo of Figure 6B.
Figure 6B. Photo of dike and sill Rock type ____ evidence_________________________________
Figure 7. Rock type ____ evidence___________________________________________
Figure 7 shows limestone in layers called strata
Figure 8.
Rock type ____ evidence___________________________________________
Sometimes ripple marks can be found in limestone like these in Figure 8.
Figure 9 Rock type ____ evidence___________________________________________
anticline
syncline
Figure 9 shows folded rocks. The top curving part of a fold is called an anticline and
the bottom curving part of the fold is called a syncline.
Figure 10. Rock type ____ evidence___________________________________________
Figure 10 shows a bed of conglomerate containing large and small sediments
Figure 11. shows a fold. Try to label the anticline and syncline?
Rock type ____ evidence___________________________________________
Figure 12. shows dinosaur fossil traces (foot prints)
Rock type ____ evidence___________________________________________
Figure 13. Figure 13 shows a bed of gneiss. See the different color wavy bands of
minerals. This is an example of foliation.
Rock type ____ evidence___________________________________________
Figure 14. Rock type ____ evidence___________________________________________
Figure 14 shows foliated rock up close.
Figure 15 shows intrusions
Rock type ____ evidence_________________________________
Figure 16.
shows a lava flow that has solidified.
Rock type ____ evidence___________________________________________
Analysis Questions:
1. How do intrusive rock features form?
2. How does a rock feature such as a lava flow form?
3. What is conglomerate and how does it form?
4. What causes foliation?
5. What kind of crystals would you find in intrusive rock features?
_____________________ (large or small)
6. What kind of crystals would you find in extrusive volcanic features?
______________________ (large or small)
7. If you saw a road cut composed of straight horizontal layers of rock, why would
you guess that it was sedimentary rock, instead of igneous or metamorphic rock?
8. Why do you think that igneous and metamorphic rock features often occur
together and not with sedimentary rock?