80 



little villages of Oxford and Concord, and the other still further 

 to the southwest, near Davison's Mill, which brings us to within 

 one mile of the Delaware river. 



I have been thus full in describing the singular phenomena of 

 induced crystallization, caused in the limestone by igneous agency, 

 and in endeavouring to trace to their several sources the various 

 extraneous minerals which accompany the alteration, from a 

 persuasion of the interesting relations of the whole subject to the 

 imporiant doctrine of the metamorphosis of rocks. 



The great thickness throughout which the limestone has under- 

 gone a most thorough crystallization from the heating agency of 

 the dikes which traverse it, and the curious law traceable in the 

 developement of some of the minerals, which appear in the light 

 of segregations from elements contained in the limestone, afford 

 unquestionably strong support to the theory, which assumes that 

 gneiss and other primary strata have once been sedimentary 

 rocks, converted by an extremely intense and wide spread igneous 

 action into a universally crystalline state. 



Respecting the question of the probable date at which the 

 mineral injections occurred, which have so singularly modified 

 the structure of the adjacent limestone, we can merely hazard 

 some general conjectures, which rest rather upon analogies than 

 upon a foundation of facts. 



Economical Relations of F. II. 



Perhaps of all the rocks in the State, the formation whose 

 geological structure we have now described, is that which is 

 most extensively and variously applicable to the useful purposes 

 of life. 



{a.) Among its several important uses, we may advert, in the 

 first place, to its adaptation as a building stone. The great 

 readiness with which it may be quarried, the facility with which 

 it may be shaped and cut, its agreeable colour, and, above all, 

 its strength and almost perfect indestructibility by atmospheric 

 agents, unite to recommend it in the construction of dwellings, 

 barns, public edifices, and the structures connected with civil 

 engineering, such as locks, bridges, and aqueducts. Lamentable 

 inattention, however, is frequently displayed in the choice of the 



