SEDIMENTARY STRUCTURES AND ENVIRONMENTS UW-GEOLOGY

1. For each of the following sedimentary rocks, describe an environment (from the

accompanying diagram) where they could be formed:

a. sandstone with fossil shells b. sandstone with grass fossils c. shale with fish fossils d. shale with worm burrows e. conglomerate f. breccia g. skeletal limestone h. chemical limestone

Figure 1

2. What kind of sedimentary structure does figure 1 show? 3. Describe a possible environment where this sedimentary rock could have formed.

Figure 2

4. What kind of sedimentary structure does figure 2 show? 5. What does it tell about its paleo-environment?

Figure 3

6. What kind of sedimentary structure does figure 3 show? 7. What does it tell about its paleo-environment?

Figure 4

8. What kind of sedimentary structure does figure 4 show? 9. What does it tell about its paleo-environment? 10. Which way was the current flowing?

Figure 5

11. Figure 5 was taken in the Great Rift Valley of Africa. The rock has been dated to be 50,000

years old. Describe the paleo-environment conditions when this footprint was made. 12. A sedimentary rock tells about the environment in which it was deposited. Sometimes a

layer-cake section (or “sequence”) of different sedimentary rocks can tell a story also. Research two sedimentary sequences – a transgressive sequence and a regressive sequence.

a) Provide a definition (in your own words) for each sequence. b) Using words and diagrams, show how both sequences could come to be formed. 13. Sedimentary rocks owe their existence to the vast amounts of water on earth that

weathers, transports and shapes them. If one is interested in finding extra-terrestrial life, one should look for water, and thus one should look for sedimentary rocks. This logic has been applied to Mars every since “canals” on the Martian surface were first seen with powerful telescopes decades ago.

a) Are there sedimentary rocks on Mars? If so, describe them. b) Has water been found on Mars? If so, where? c) Has life been found on Mars? If so, what kind?