Final answer:
Materials in glacier lakes are sorted mostly by sedimentation by density during processes like spring turnover. Sediments from various sources settle differently based on their density, with other factors such as topography and human activity also affecting distribution. Global warming and melting ice can alter these patterns and lake levels.
Step-by-step explanation:
The materials in glacier lakes are sorted primarily due to sedimentation by density. As the glacier melts, different materials are carried along with the water into the lake. Heavier and denser particles settle to the bottom first, while lighter sediments settle more slowly and may be suspended or distributed at various depths. This process is part of spring turnover, where the warming surface water sinks and stirs up nutrients and sediments from the bottom layers, contributing to their distribution within the lake.
Some percentage of the lake sediment can originate from various sources, and its distribution can be influenced by factors such as water movement, melting and refreezing cycles, the topography of the lakebed, and human or natural activities in the surrounding area. If a significant difference in sediment source percentages is observed, it could be due to varying erosion rates, different types of bedrock or vegetation, or human intervention like construction or deforestation altering sediment supply.
Furthermore, when considering large-scale melting due to global warming, a glacier sitting on land would contribute more to the lake level when melted as compared to an iceberg already floating in the lake, which is based on the principle of displacement. As the climate changes, these patterns and contributions to sedimentation will also vary.