7. Which president led the United States through the end of the Cold War?

Harry S. Truman

Explanation:

1. According to the law of superposition, if the terrain was undisturbed, the layer E would be the youngest and the layer A would be the oldest.

2. The law of horizontality states that sediment deposited into water will settle at the bottom in flat, horizontal layers. This would make us expect that we could find layer D in sector 3. To explain the absence, if none of the stratum D species lived there, there would be no stratum D fossils there.

3. The law of faunal and floral succession suggests that the graphic did not go through any geologic processes after deposition.

4. According to the law of cross-cutting relationships, Layer A is the oldest, and Magma F is the youngest.