noun
inner wall; inner rockface
Refers to the innermost wall or rockface of a cave, mountain valley, or similar enclosed natural space. Often used in contexts like caving, climbing, or describing deep mountain scenery.
洞窟の奥壁には、古代の壁画が残っていた。
Ancient murals remained on the inner wall of the cave.
谷の奥壁から滝が流れ落ちている。
A waterfall cascades down from the inner rockface of the valley.