rift valley

n steep-sided valley caused by subsidence of the earth's crust 地堑; 裂谷.

ridge-pole, ridge-tile, ridgeway, ridicule, ridiculous, ridiculously, ridiculousness, riding, riding-crop, riding-school, rife, riff, riff-raff, riffle, riffraff, rifle, rifle-range, rifleman, rifling, rift, rig, rig-out, rigging, right, right angle, right away, Right Honourable, right of way, Right Reverend, right-handed, right-minded, right-mindedness, righteous, righteously, righteousness, rightful, rightfully, rightly, rightness, rights issue,