The amount of black rain varies not only between large areas but also within this cracked-soil region, with those places closer to the low hills experiencing denser rainfall.
The center of these low hills shows evidence of past eruptions; they are hollow inside, and from a distance, they resemble several volcanoes. However, upon closer inspection, these hills are not like typical volcanoes. Their main composition is not volcanic rock but a substance somewhat similar to soil.
Xu Huo used a tool to dig a bit and found that the low hills were not as solid as expected. Instead, the interior was loose, like overturned fine soil. It required little effort to pry apart, disintegrating upon a light pinch, much like the black filaments mixed in with the rain, dissolving in hand.
The so-called "low hills" were not real hills, but were large conical mounds formed from the accumulation of this black filamentous substance.
