Passage VII

Glaciers deposit till (a poorly sorted sediment). If glaciers repeatedly advance over an area and then melt back, thick till deposits may form. Figure 1 shows a vertical core taken through layers of till, non-glacial sediments, and bedrock at a site in Canada. The resistivity (an electrical property of a material) and CO2 measurements taken along the core are also shown. Resistivity is related to a sediment's particle sizes, compaction, and mineral composition. Table 1 shows the average percent sand, silt, and clay contents and descriptions of the various till layers.

Figure 1 and Table 1 adapted from E. A. Christiansen, "Pleistocene Stratigraphy of the Saskatoon Area, Saskatchewan, Canada: An Update." ©1992 by the Geological Association of Canada.

36. A sample of gray till was recovered from another core taken from a nearby area. The table below shows the results of an analysis of the sample.

Based on these data and the data provided in Figure 1 and Table 1, the sample of gray till corresponds most closely with which till from Figure 1 ?

Answer and Explanation

Your Answer is

Correct Answer is H

Explanation

Look at the percent by volume of in the table in the comparison question and the average percent by volume of in table 1, and find that it is closest to gray C;

Take resistance & CO2

sub> content Go to figure 1 for comparison, and find that it is more consistent with gray till C