LIFE OF JAMES DWIGHT DANA 



mountains and the trap ranges of central New England 

 are results of subterranean forces acting upon the earth's 

 crust according to common laws. The State of Connec- 

 ticut, through the mind and labors of Percival, has con- 

 tributed the best and fullest exemplification of the laws 

 yet obtained, and thus prepared the way for a correct 

 understanding of the great features of the globe. 



" The red sandstone rocks of the region teach that, in 

 mediaeval geological time, the waters made a continuous 

 estuary from New Haven, on Long Island Sound, to 

 northern Massachusetts, one continuous Connecticut 

 River, or estuary, with New Haven as its southern ter- 

 minus. The question then suggests itself, why does not 

 the river flow now in this Connecticut Valley down to 

 New Haven Bay ? Percival's investigations afford the 

 answer, although he has not suggested it. He shows on 

 his map, as observed above, that the trap ridges make a 

 nearly east and west course across the valley in the region 

 of the Meriden Hills, just opposite the spot where the 

 Connecticut River takes its eastern bend. Evidently the 

 making of these hills, that is, the rending of the earth's 

 crust, the ejection of the melted trap rock, and the ac- 

 companying uplifting of the surface, might well have 

 forced the river out of its older course, and, without a 

 doubt, it so did ; and thus New Haven lost its great river. 



' Percival pursued his second subject, that of the 

 granitic rocks, with similar fidelity, and mapped out with 

 care the several formations. The State, however, was too 

 large for the satisfactory completion of the Survey in the 

 short time allotted to it. The subject, besides, was 

 vastly more complex and difficult than that of the trap 

 ridges and the associated sandstone. He began the work 

 well, but had to leave it for some future observer to finish. 



' With regard to these rocks, his mind became early 

 entangled with a theory, bold and comprehensive, and 

 likely to captivate a poetical mind, but one which geo- 

 logical science has never favored. It was, however, with 

 him, only an incentive to more scrutinizing research. He 

 thought of it and talked about it at great length at times, 

 with his one or two friends who had ears for such sub- 

 jects. But his speculations nowhere appear in his Report. 

 His labors, moreover, were not without practical re- 

 sults ; for he was the first to explain correctly the origin 



