6 And there was great calamity in all the land, for they [the prophets] had testified that a great curse should come upon the land, and also upon the people, and that there should be a great destruction among them, such an one as never had been upon the face of the earth, and their bones should become as heaps of earth upon the face of the land except they should repent of their wickedness.The mention of "heaps of earth" is interesting and seems to refer to the manner of digging for precious metals described in Ether 10:23. This adds some poetic flair to the words of the prophets, along the lines of: "Just as you create these heaps of earth in search for your precious ore, the Lord will cause your bones to become as heaps of earth except you should repent."
There are numerous references in the Book of Mormon to the fulfillment of this prophecy, which we read about in gruesome detail in Ether 14:21-23:
21 And so great and lasting had been the war, and so long had been the scene of bloodshed and carnage, that the whole face of the land was covered with the bodies of the dead.In Omni 1:22, we read:
22 And so swift and speedy was the war that there was none left to bury the dead, but they did march forth from the shedding of blood to the shedding of blood, leaving the bodies of both men, women, and children strewed upon the face of the land, to become a prey to the worms of the flesh.
23 And the scent thereof went forth upon the face of the land, even upon all the face of the land; wherefore the people became troubled by day and by night, because of the scent thereof.
22 It also spake a few words concerning his fathers. And his first parents came out from the tower, at the time the Lord confounded the language of the people; and the severity of the Lord fell upon them according to his judgments, which are just; and their bones lay scattered in the land northward.Mosiah 8 also has a reference to the bones:
8 And they were lost in the wilderness for the space of many days, yet they were diligent, and found not the land of Zarahemla but returned to this land, having traveled in a land among many waters, having discovered a land which was covered with bones of men, and of beasts, and was also covered with ruins of buildings of every kind, having discovered a land which had been peopled with a people who were as numerous as the hosts of Israel.In Mosiah 21:26, we get another reference:
26 Nevertheless, they did find a land which had been peopled; yea, a land which was covered with dry bones; yea, a land which had been peopled and which had been destroyed; and they, having supposed it to be the land of Zarahemla, returned to the land of Nephi, having arrived in the borders of the land not many days before the coming of Ammon.In Alma 22:30, there is yet another reference:
30 And it bordered upon the land which they called Desolation, it being so far northward that it came into the land which had been peopled and been destroyed, of whose bones we have spoken, which was discovered by the people of Zarahemla, it being the place of their first landing.