Final answer:
Iowa was covered by a continental ice sheet during the last Ice Age, part of the Laurentide Ice Sheet. The movement of this ice sheet shaped the state's landscape, and sediment analysis helps to track the ice sheet's historical extent and movements.
Step-by-step explanation:
The state of Iowa was covered by a continental ice sheet during the last Ice Age. Valley ice sheets are typically found in high mountain valleys, whereas continental ice sheets cover much larger areas and can encompass entire continents. The ice sheet that covered Iowa was part of a larger ice mass that affected much of North America, known as the Laurentide Ice Sheet. As this ice sheet moved, it caused weathering and erosion of the underlying rock, helping to shape the landscape of the area.
When considering sediment deposits and their geochemical fingerprints, geologists can determine the edge of the ice sheets and understand the historical movement of ice across the continent. These movements help to identify periods of advance and retreat of the ice sheet, which in turn gives insights into past climate conditions. For instance, diatom-rich layers in sediment cores can suggest times when the ice sheet was retreating, while diatom-poor layers might indicate an advance toward the coastline.