Harry suddenly realized that the tape measure, which was measuring between his nostrils, was doing this on its own. Mr. Ollivander was flitting around the shelves, taking down boxes. "That will do," he said, and the tape measure crumpled into a heap on the floor. "Right then, Mr. Potter. Try this one. Beechwood and dragon heartstrings. Nine inches. Nice and flexible. just take it and give it a wave."
What do "crumple" and "heap" mean in the sentence "the tape measure crumpled into the heap on the floor"?
Crumple is meant like this in Oxford:
1.1 no object Become bent, crooked, or creased.
The question is why should a tape measure become bent, crooked or creased? What is the meaning of "heap" here? Does it mean that the tape measure has turned into a heap? It doesn't make sense. Or is heap just an untidy pile of things that the wrinkled! tape measure has fallen on it? Does "crumple" mean fall here? It can't be since Oxfords definition 1.2 has plainly mentioned "(of a person").