This mountain range extende of it was a alone the eastern part of the seacoast States, and west Adironthe r Whethe . <>Teat sea in the present Mississippi Valley connected, and daeks and this Highland mountain range were ever told in the w'lia! was the actual extension of the two areas, can not be of much of the present state of geological knowledge, the record of later ages. earlv history having been hidden beneath the strata sea beat at However in verv earlv Paleozoic times the waves of the then at were these and ds, Highlan n the western base of the souther an time that at was which area, ack Adirond Least separated from the island in the Paleozoic sea. the relations Professor dames I). Dana, in an inquiry concerning at the concluof the limestone belts of Westchester County, arrives of Lower sion that, with those of New York Island, they are probably assoably comform the age same the Silurian a*e, assigning also to Westchester ciated metamorphic rocks. He holds to the view that the Green Mountain County belongs to the same geologic period as which is now reoion resembling in its order that portion of the latter for believing that western Connecticut. Other geologists find reason Green Mountain the Westchester rocks are older than those of the Silurian. It Lower the area ami belong to an even earlier age than of W estmarbles the and is pointed out that the marbles of Vermont lly different chester County, with their associated rocks, are essentia f,-,>m one another, and can hardly, therefore, belong to a common belt and formation; the Vermont marbles being found in a single banded and mottled of and behio' almost pure carbonates of lime, es, quartzit es, limeston s siliceou gray with -rained, appearance, tine ster marbles and slates identified with them; whereas the Westche crystalline doloconstitute a series of parallel belts and are - coarsely carbonates of lime and magnesia ) , generally of uniform i mitesdouble them that white or whitish color, and have no rocks associated with ." Vermont of s can represeni the quartzites and argillite the W estStill another opinion regarding the origin of the rocks of believes who cdiester County regions is that of Prof.