Q: Given a scientific passage and an answer, generate a question for the given answer.
Passage: Several types of stratified deposits form in glacial regions but are not formed directly by the ice. Varves form where lakes are covered by ice in the winter. Dark, fine-grained clays sink to the bottom of the lake in winter. Melting ice in the spring brings running water that deposits lighter colored sands. Each alternating dark/light layer represents one year of deposits. Answer: varves
A:
What type of stratified deposit is formed where lakes are covered by ice in the winter?