Over a few decades the world has changed beyond recognition — truly a sense of high banks turned to deep valleys.
Tips
history
From the 《诗经·小雅·十月之交》: 高岸为谷，深谷为陵 ('high banks become valleys, deep valleys become hills') — a prophecy of cataclysmic change. The compressed idiom keeps both the literal landscape and the figurative 'world turned upside down' senses.
