A possible meaning of the metaphor would be very disappointed because "dirt disappointed" is not meant in a positive sort of way. If you're dirt disappointed it most likely means you are very disappointed, possibly aggravated. Hope this helps
The main idea of this paragraph is that the rocks cannot be explained by science, that there is a mystery to them. This sentence contributes to that idea because it gives a specific example of one of the odd things about the rocks. Because they are on a flat surface they should not roll or move on their own, but the fact that they have a trail behind them shows that they have somehow moved. This supporting statement is then supported by more details about the trails.
The answer i think would be subject
Answer:
You should be asking 2 things, how can I use it in my own writing and what is the meaning and effect of this technique