Which description is appropriately match the characteristics of coral reef?
A. chemical changes or high water temperatures increase calcium carbonate concentrations to the point of precipitation
B. relatively simple invertebrate animals secrete a calcareous skeleton and grow together
C. biochemical limestone where shell fragments are poorly cemented together
D. composed of small spherical grains, commonly small shell fragments, coated with precipitated calcium carbonate
查看答案
Which type of sedimentary structure can be used to determine current direction?
A. grain size sorting and ripple marks
B. mud cracks and ripple marks
C. ripple marks and cross-bedding
D. fossils and mud cracks
Which one of the following is NOT a type of sedimentary structure?
A. bedding planes
B. striations
C. cross-bedding
D. graded beds
E. ripple marks
F. mud cracks
What is the difference between conglomerate and breccia?
A. Breccia clasts are the size of boulders, whereas conglomerate clasts are very fine grained.
B. A breccia is well stratified, whereas a conglomerate is poorly stratified.
C. Breccia clasts are angular, whereas conglomerate clasts are rounded.
D. Breccia has a compacted, clay-rich matrix, whereas conglomerate has no matrix.
How are the degree of sorting and the amount of rounding of grains related to the transportation of sand grains?
A. The rounder and better sorted grains indicate farther travel from the source.
B. The more angular and poorly sorted grains indicate shorter travel from the source and higher energy of the environment of deposition.
C. The rounder and better sorted grains indicate shorter travel from the source.
D. The more angular and poorly sorted grains indicate farther travel from the source and lower energy of the environment of deposition.
微信支付 
支付宝支付