Though our science has risen above the stage from which she taught that all granites are parts of the original crust of the earth; though she has advanced so far as to doubt whether, in all cases, the granitic was the first phase of rock-existence which the materials composing it assumed, and to entertain the question whether such rocks may not be the extreme form of metamorphism, which has obliterated all traces of an earlier condition; and though she may prudently decline to point out, in the large circle of her rocky acquaintances, one mass of crystalline unstratified rock which, as such, can be proved to be older than some known beds of mechanical origin; it remains to be the rule rather than the exception to meet with persons, frequently veil-informed, and not without an interest in geology, who still cling to the notion, or allow it to cling to them, that every mass of granite is a primitive rock, in the strict chronological import of the term; and represents a period in the earth's history prior to the possible existence of sedimentary strata, or of organized beings. Indeed the opinion that granite is, in all cases, a primary rock, has so large a place in the public mind, that one might prudently hesitate before throwing such a question as “What is the age of the Dartmoor granite?” before any audience having a very large admixture of the popular element.