Question

which are glacial lake sediments that show cycles of deposition?
annual rings
tillites
varves
unconformities

Explanation:

• Annual rings are related to trees, not glacial lake sediments.
• Tillites are sedimentary rocks formed from till (glacial sediment), but not specifically showing cyclic deposition in lakes.
• Varves are layers of sediment (usually clay and silt) deposited in glacial lakes. Each varve represents one year's worth of deposition (a light - colored layer from summer deposition and a dark - colored layer from winter deposition), showing cycles of deposition.
• Unconformities are gaps in the geological record (e.g., erosion surfaces between rock layers), not related to cyclic lake sediment deposition.

Answer:

varves