Land Canyons vs. Ocean Trenches: Similarities and Differences

Both are deep, narrow valleys with steep walls. Land canyons form from river/stream erosion over millennia (e.g., Grand Canyon). Ocean trenches result from tectonic subduction, where one plate dives beneath another (e.g., Mariana Trench). Canyons reach ~1,000 m deep; trenches exceed 11,000 m. Different erosive agents—water vs. plate tectonics—shape them.