Some think that volcanic action was involved, for often volcanoes belch out smoke and dust that blacken the sky.
Ada yang berpendapat bahwa kegelapan itu mungkin berkaitan dengan kegiatan vulkanis, sebab sering kali gunung-gunung berapi memuntahkan asap dan debu yang menggelapkan langit.
Where this develops into chronic gastritis, the symptoms, if present, are often those of nonulcer dyspepsia: stomach pains, nausea, bloating, belching, and sometimes vomiting or black stool.