Assertion: spreading ridge | /r/HasProperty | less than 40 mm/yr
Facets:
Source sentences:
text: Slow-spreading ridges (less than 40 mm/yr) generally have large rift valleys, sometimes as wide as 10–20 km (6.2–12.4 mi), and very rugged terrain at the ridge crest that can have relief of up to a 1,000 m (3,300 ft).