Excerpt from Excelsior, Vol. 4: Helps to Progress in Religion, Science, and Literature We must then commence by telling him that the ordi nary rocks which he sees used for building-stones, for paving the streets, &c., or those which he meets with in clifl's or quarries, or of which he sees the rolled and rounded fragments in gravel-pits, were all formed in one of two ways. They have either cooled from a molten condition, the result of intense heat, or they have been deposited and compacted together under water. They are called, there fore, Igneous rocks and Aqueous rocks: The latter are often called Sedimentary, as being the result of the deposi tion of sediment in water; and Stratified, because they have been strewed out so as to form wide sheets, or beds, or strata. The igneous rocks, on the other hand, are often called the Unstratified rocks.

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