* Temperature: Colder glaciers require a greater thickness to start flowing than warmer ones.
* Ice composition: Glaciers with higher proportions of impurities (like rocks and sediment) will flow more slowly than those with purer ice.
* Slope: Glaciers on steeper slopes will begin flowing at a lower thickness than those on gentler slopes.
* Underlying bedrock: The nature of the bedrock beneath the glacier can influence its flow.
* Pressure: The weight of the ice itself plays a significant role in initiating flow.
Generally speaking:
* Thinner glaciers: Tend to be more influenced by the underlying topography and can deform relatively easily.
* Thicker glaciers: Exhibit more plastic behavior, allowing them to flow under their own weight.
To give you an idea:
* A glacier might start flowing at around 30 meters thick in a very cold environment with a steep slope.
* In a warmer climate with a gentler slope, it might require 50-100 meters or more to begin flowing.
Therefore, it's not about a fixed "critical thickness," but rather a combination of factors that contribute to the initiation of glacial flow.
