Final answer:
Needle ice on sloped surfaces contributes to soil creep by lifting and separating soil particles, leading to a slow, downward progression of materials affecting the landscape's stability.
Step-by-step explanation:
The question, 'What can needle ice do on sloped surfaces?' is related to physical geography and the effects of freeze-thaw processes on landscapes. Needle ice forms when the soil temperature is above 0°C and the air temperature is below freezing. This causes water to move up through the soil by capillary action and then freeze upon exposure to the air, forming ice needles perpendicular to the ground.
On sloped surfaces, the formation of needle ice can contribute to soil creep, which is a slow, downward progression of soil and rock. As needle ice grows, it lifts and separates soil particles, and as it melts, these particles may move slightly downhill due to gravity. Over time, this process can cause significant movement of material and can affect the stability of slopes, leading to erosional features or changes in the landscape.