Passage I

A catchment (drainage basin) is a geographical area that drains to a given point along a river. Geologists studied catchments to understand relationships between climate, the quantities of water flowing through the catchments, and the erosion of the landscape.

Study 1

Eight catchments of similar area in different locations were chosen for study: 3 with limestone bedrock, 2 with quartzite bedrock, and 3 with granite bedrock. The dissolved load (weathered material carried in solution by water) and the solid load (solid particles carried by water) were measured for each catchment, in tons per square kilometer per year (tons/km2/yr). The rate at which the landscape was being eroded in each catchment, in centimeters per 1,000 years (cm/1,000 yr), was also measured. The results are in Table 1.

Study 2

Measurements were taken of the average annual air temperature, in degrees Celsius (°C), and the total annual precipitation, in cm, within the 8 catchments. The results are in Table 2.

Study 3

Geologists measured the discharge from each catchment. Discharge is the amount of water, in cubic meters per second (m3/sec), leaving a catchment. Annual precipitation from Study 2 was plotted against average discharge for the 8 catchments. The results are in Figure 1.

5. Dissolved load in a catchment is produced by chemical weathering, while solid load is produced by mechanical weathering. According to this information and the results of Study 1, which of the following statements about weathering is most likely true?

Answer and Explanation

Your Answer is

Correct Answer is B

Explanation

Locating Table 1, catchmentA, B, and C are all based on limestone. The latter two loads indicate how many tons of limestone will be lost per cubic kilometer per year. It is obvious that dissolved is much more than solid. According to the question stem, the weathering corresponding to dissolved is chemical weathering, so I am more afraid of chemical weathering