Final answer:
Glacier meltwater rivers sort materials by size and weight, arranging sediments from larger to finer downstream. Glaciers are significant agents of erosion and play a crucial role in shaping landscapes and influencing soil development.
Step-by-step explanation:
Glacier meltwater rivers sort materials primarily by size and weight. The mechanism is simple; as the river flows away from the glacier, the speed of the current decreases and the heavier particles settle more quickly than the lighter ones. This natural sorting arranges sediments in order of their size, starting with larger boulders and rocks upstream to finer sediments like sands and silts downstream.
During this transport phase, glaciers act as powerful agents of erosion, scraping and grinding down rocks as well as carrying loads of gravel and boulders from high altitudes to lower areas. When the ice melts, the process results in a more unordered system where heat transfer increases the entropy or disorder, as the systematic arrangement typical of ice structure becomes randomized in liquid water.
Erosion shapes the Earth's surface, carving river valleys in mountains and forming cliffs and caves in coastal regions. The sediment deposited in rivers or near-shore marine environments eventually becomes part of the soil profile, influencing the type of soil that develops over time, which is vital for supporting ecosystems.