Page:Popular Science Monthly Volume 40.djvu/233

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SEVERAL years ago, while walking down the lower Connecticut valley with a party of students, we chanced upon a curious ledge of rock surmounting a low ridge by the road that runs from Berlin to Meriden, about half-way between Hartford and New Haven. A scramble up the slope through a bushy growth of young trees led to the foot of the ledge—a thick bed of gray-greenish rock, not in layers like limestone or sandstone, not crystalline like granite or gneiss, but of a loose, structureless texture, here and there carrying roughly rounded blocks of a dense, dark rock which we knew to be an old lava, from its resemblance to the rocks ejected from modern volcanoes. Although a ledge of this kind is not of ordinary occurrence, its features were so well marked that there could be little doubt of its nature and origin; it was a bed of volcanic ashes, interspersed with blocks or bombs of lava that must have been thrown from some neighboring vent long ago in the ancient time when the rocks of the valley were made. The ash-bed lay upon a series of muddy sandstones that

PSM V40 D233 Lava block under water in soft sandy mud.jpg
Fig. 1.

had evidently been formed under water, for they were deposited in layers, just as sand and mud are now when they are washed into a pond; and to all appearances the eruption of the ashes and bombs had taken place during the accumulation of the sandstones. The ashes had fallen into the water and settled down gently on the soft, sandy mud at the bottom; one of the dense lava blocks was seen to have indented itself in the sandy layers, bending them down on either side of it, just as if it had been an early product of