Final answer:
Yosemite Valley's U-shaped profile was created by glaciers, while the sediments filling it partially are from weathered and eroded material.
Step-by-step explanation:
The U-shaped profile of Yosemite Valley was shaped by glacial activity during the last ice age. Glaciers carved through the valley, sculpting its walls and deepening its floor to create the U-shaped cross-section.
After the glaciers retreated, the valley was filled with sediments through processes such as rock fall, landslides, and streams depositing material eroded from the surrounding slopes into the valley floor over time.
Sediments in the valley likely formed from the weathering and erosion of the surrounding rock faces, leading to an accumulation of debris. This debris could have been transported by water or gravity and deposited, forming layers of sediment that partially fill the valley. The sediments also tell a story of the region's past environments and changes over geological time.