XIII.] GEOGNOSY OF THE APPALACHIANS. 327 



many others, all of whom assigned the crystalline schists of the 

 White Mountains to a higher geological horizon than those of 

 the Green Mountains. In support of this view of their relative 

 antiquity, I have, however, brought together observations from 

 South Carolina, Pennsylvania, Michigan, Ontario, and Maine, all of 

 which point to the same conclusion ; and I might now add similar 

 evidence from New Brunswick and from Nova Scotia. My " chrono- 

 logical arrangement" of New England crystalline rocks, as it is 

 called by Professor Dana, so far as it is my own, is limited to my 

 affirmation that they are all of pre-Cambrian age ; in proof of 

 which it need only be mentioned that the crystalline schists of both 

 the types in question are, in southern New Brunswick, directly 

 overlaid by uncrystalline shales, sandstones and conglomerates, 

 made up in part of the ruins of these, and holding a Cambrian 

 (Menevian) fauna. 



As regards the mica-schists with staurolite, cyanite, andalusite, 

 and garnet, I have in my address pointed out the fact that they 

 appear to belong to a great series of rocks, very constant in charac- 

 ter, which have a continuous outcrop from the Hudson River to 

 the St. John, a distance of five hundred miles, and in the latter 

 region are clearly pre-Cambrian. I have, moreover, brought to- 

 gether the evidence of observers in other parts of North America, 

 in Great Britain, in continental Europe, and in Australia, showing 

 that similar crystalline schists, holding these same minerals, always 

 occupy, in these regions, a similar geological horizon. Professor 

 Dana hereupon inquires whether any one has yet proved that these 

 mineral characters are restricted to rocks of a certain geological 

 period. I answer, that in opposition to these facts, it has not yet 

 been proved that they belong to any later geological period than 

 the one already indicated ; and that it is only by bringing together 

 observations, as I have done, that we can ever hope to determine 

 the geological value of these mineral fossils. In no other way did 

 William Smith prove, in Great Britain, the value of organic fossils, 

 and thus lay the foundations of paleontological geology. 



