The Blue Ridge, on each side of the Patowmac, is formed, from the foundation to the summit, of large rocks deposited in beds of rich soft earth. This earth is very readily washed away, and in that case the rocks consequently become loose; indeed, they are frequently loosened even by heavy showers of rain. A proof of this came within my own observation, which I shall never forget. It had been raining excessively hard the whole morning of that day on which I arrived at this place; the evening however was very fine, and being anxious to behold the scene in every point of view, I crossed the river, and attended the mountain at a steep part on the opposite side, where there was no path, and many large projecting rocks. I had walked up about fifty yards, when a large stone that I set my foot upon, and which appeared to me perfectly firm, all at once gave way; it had been loosened by the rain, and brought down such a heap of others with it in its fall, with such a tremendous noise at the same time, that I thought the whole mountain was coming upon me, and expected every moment to be dashed to pieces. I slid down about twenty feet, and then luckily caught hold of the branch of a tree, by which I clung; but the stones still continued to roll down heap after heap; several times, likewise, after all had been still for a minute or two, they again began to fall with increased violence. In this state of suspense I was kept for a considerable time, not knowing but that some stone larger than the rest might give way, and carry down with it even the tree by which I held. Unacquainted also with the paths of the mountain, there seemed to me to be no other way of getting down, excepting over the fallen stones, a way which I contemplated with horror. Night however was coming on very fast; it was absolutely necessary to quit the situation I was in, and fortunately I got to the bottom without receiving any further injury than two or three slight contusions on my hips and elbows. The people congratulated me when I came back on my escape, and informed me, that the stones very commonly gave way in this manner after heavy falls of rain; but on the dissolution of a large body of snow, immense rocks, they said, would sometimes roll down with a crash that might be heard for miles. The consequences then of a large rock towards the bottom of the mountain being undermined by a flood, and giving way, may be very readily imagined: the rock above it, robbed of its support, would also fall; this would bring down with it numbers of others with which it was connected, and thus a disruption would be produced from the base to the very summit of the mountain. [Sidenote: IRON.]