Passage VII

Tiny marine organisms build shells from calcite (CaCO3) dissolved in seawater. After the organisms’ death, the shells sink. Some shells dissolve before they reach the seafloor, but some form layers of calcareous ooze (CaCO3-rich sediment). Figure 1 shows how seawater’s degree of saturation with respect to CaCO3 and the rate at which CaCO3 dissolves change with depth. The CaCO3 compensation depth (CCD) represents the depth beneath which CaCO3 dissolves faster than it precipitates. Figure 2 shows typical depths at which various seafloor sediments are found. Figure 3 shows the percent coverage for 2 seafloor sediments in 3 oceans.

37. The data in Figure 2 support which of the following statements about the relative thickness of marine organism shells and the depths at which calcareous oozes composed of those shells are found ? Calcareous oozes formed mainly from thick-shelled organisms are found:

Answer and Explanation

Your Answer is

Correct Answer is B

Explanation

As can be seen from figure 2, the calcareous ooze composed of thin-shelled organisms is at a shallower position, while the calcareous ooze composed of thick-shelled organisms is at a deeper level