If two glaciers move along opposite side of the mountain, they erode both sides of the ridge, forming a narrow arete between valleys.
(two glaciers; move; along opposite side of the mountain) (they; erode; both sides of the ridge) Context(they erode,List([58, 68))):(they; erode both sides of the ridge forming; a narrow arete between valleys)
they erode,List([58, 68))
two glaciers they they
move erode erode both sides of the ridge forming
along opposite side of the mountain
both sides of the ridge
a narrow arete between valleys