BJU test 2 review geology chapter 6
19. A boundary surface of a formation is
a contact
9. Prior to compaction, deposits of sand in a quiet environment may have ______ volume open pore space.
a. 40-50%
4. Limestones
a. All of others are valid b. Form in a marine environment, Form in fresh water, Form by inorganic precipitation
5. Which kind of information can be determined from sedimentary structures?
a. All of the other choices are correct b. Means of transport of sediment, depositional environment, topping direction
26. The main criterion for recognizing a formation is
a. An easily recognizable and mappable assemblage of rocks
23. A sedimentary breccia consists of
a. Angular rock and mineral fragments
22. Detrital grains of some mineral(s) are extremely rare in detrital sediments. Which minerals and why?
a. Calcite- it is soft and relatively soluble in water
25. Which one of the following is NOT considered a physical process of diagenesis?
a. Cementation b. Considered a physical process of diagenesis: crystallization, lithification, compaction
15. What are terms for the two principal sources of sediment that produce the two principal types of sedimentary rocks?
a. Detrital and chemical
28. Which of the following is true for minerals in chemical sedimentary rocks that form by evaporation?
a. Evaporite minerals are more soluble than calcite and quartz
17. Clastic sedimentary rocks are characterized by
a. Grains bound by cement into a rigid framework
6. Turbidity currents commonly deposit
a. Gray wacke
3. Which of the following is not a chemical sedimentary rock?
a. Graywacke b. Chemical sedimentary rock (limestone, chert, dolomite)
16. What is the primary basis for distinguishing among various detrital sedimentary rocks? Why?
a. Particle size- a useful observation indicating the environment of deposition.
13. Most large dolomite beds were formed by
a. Recrystallization or replacement of limestone
24. In a transgression, sea level
a. Rises
7. Which is not an evaporite rock?
a. Shale b. Rock salt, rock gypsum, halite are evaporite rock
14. Select the answer that lists the common clastic sedimentary rocks in order of increasing particle size
a. Shale, sandstone, conglomerate
18. Ooids in inorganic limestone characteristically form in
a. Shallow warm marine waters
29. As a river begins to lose energy
a. The largest particles settle out first
12. Quartz sandstone is a ______ rock and is typically deposited as a ______
a. Well sorted, sand dune
1. When a body of seawater evaporates, minerals precipitate in a certain order. What determines this order?
a. mineral solubility - less soluble minerals precipitate first, more soluble minerals precipitate later
8. A rock that contains sediment grains bound together by cement is called
clastic
27. Which is a type of sedimentary rock composed mainly of all fossil material?
coquina
10. Which type of sedimentary rock is NOT formed by either compaction or cementation?
evaporate
20. The minerals gypsum and halite are found deposited in lake environments. Which kind of chemical sedimentary rock do they form?
evaporites
21. Which are not sedimentary structures?
fossils
2. Which of the following does not contain information about paleocurrents?
laminar bedding
11. Which of the following rocks is most likely to have been deposited in an environment of cold, quiet water?
shale
