PHYSICAL HISTORY OF NEW HAMPSHIRE. 529 



hundred or one thousand feet elsewhere, as in the Twins, and Mts. Flume 

 and Liberty. It crops out also near the summit of Lafayette. A third 

 outburst was more limited, but it gave rise to the sharp peak of Cho- 

 corua and to small hills west of Mt. Hancock, which I term the CJiocorua 

 granite. It is likely that corresponding eruptions gave rise to similar 

 granites in the Starr King group of mountains, Stratford and Columbia, 

 the granitic country of Essex county, the gores of wild land east of 

 Montpelier, Little Ascutney, and about Cuttingsville, Vt, besides the 

 Ossipee mountains east of Winnipiseogee. Possibly the latter may have 

 accumulated by a branch stream running southerly from the Saco river 

 outburst. This granite, when finally cooled off, seems to have been 

 covered by water, since there succeeds a great thickness of fine sedi- 

 mentary deposits. This proves to be of four kinds, coarse and fine 

 labradorites and variously colored potash feldspars above the first We 

 suppose these must have covered the granites, or nearly so. When this 

 basin was full, there would be a level country from Lafayette across to 

 Mt. Tom, just back of the Crawford house. 



It seems strange that the topographical aspect of a portion of the 

 White Mountains more nearly resembles the eroded Carboniferous pla- 

 teau of West Virginia than any other district. The character of these 

 mountains may be predicted in advance of examination, since there is so 

 general a correspondence between altitude and lithological structure. If 

 a five-thousand-feet mountain shows the Conway granite at its base, fel- 

 sites may be looked for at its summit. Pemigewasset has in it three 

 mountain ranges running southerly, Lafayette on the west, and Mt. 

 Tom on the east ; both these and the central Twin mountains show the 

 whole series from the low granite to the upper felsites, while the inter- 

 vening ranges have been removed by erosion down to the lowest granite, 

 the formations reposing horizontally. This is like the narrow valleys in 

 West Virginia, cut through by the Kanawha and Guyandotte rivers and 

 their tributaries. The map shows a smaller Labrador area resting upon 

 the Green Mountain range near Cuttingsville on the Rutland & Burling- 

 ton Railroad, and not a great distance from Rutland. This area is com- 

 posed apparently of the Chocorua granite, resting upon Montalban gneiss. 

 It is an interesting locality, because it shows the similarity between the 

 formation of the White and Green mountains. The succession of the 

 VOL. i. 69 



