Q: Write an inquisitive question about a specific text span in a given sentence such that the answer is not in the text.
Sentence: She is one of many experts who have combed the terrain for clues on the origin of these potentially dangerous holes , which are about a foot in diameter and seem to survive for less than a day before filling in naturally with sand .<sep>Span: potentially dangerous holes ,
A:
How are these holes particularly dangerous?