Which geologic process primarily scours and deepens a fjord's U-shaped valley profile?

💡 Explanation

When glaciers move through existing valleys, glacial abrasion occurs because ice embedded with rock fragments scrapes along the bedrock, deepening and widening the valley floor and walls. Therefore glacial abrasion results, rather than tectonic uplift, chemical weathering, or sediment deposition which operate on different timescales and geological settings.

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