Assertion: terrestrial planet's canyon | /r/HasAspect | a length of 4,000 km
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Source sentences:
text: The large canyon, Valles Marineris (Latin for "Mariner Valleys", also known as Agathadaemon in the old canal maps), has a length of 4,000 km (2,500 mi) and a depth of up to 7 km (4.3 mi).