沖積平野

1. Origins, structure, and basic meaning

• Structure: 沖積平野 is read as ちゅうせきへいや and is a geographical noun for an alluvial plain formed by material deposited by a river.
• Basic usage: The landform can 広がる, while its mapped area is expressed as 沖積平野の範囲.

2. Common pitfalls and similar expressions

• River and plain
  • The lower reaches identify where the plain lies; 沖積平野 is the surrounding flat landform, not the river itself.
• Landform and mapped extent
  • 広がる describes the actual spread of the plain, whereas 範囲を色分けする describes marking its area on a topographic map.