GEOLOGY OF THE WHITE MOUNTAIN DISTRICT, 233 



section, show that the rock is composed of orthoclase feldspar, a foliated mineral re- 

 sembling chloritoid, titanic iron, and a few flakes of mica. The titanic iron is dissemi- 

 nated all through the rock, in very minute particles, and the analysis shows that it 

 constitutes four per cent, of the whole. The feldspar is very poorly crystallized ; and 

 the pei'centage of alkali shows that nearly half the rock is common feldspar. Deduct- 

 ing the titanic iron and orthoclase, we have a percentage which nearly represents the 

 mineral chloritoid, and the variation from it is accounted for by the presence of the 

 hydrated mica, which can easily be seen. The low percentage of silica accounts for 

 the great difference from the granites on each side, which. Prof. Dana has told me, 

 are so placed ; and the analysis shows that this was a much more muddy layer, which 

 did not possess the necessary ingredients to be changed into granite by metamorphic 

 action. 



Yours faithfully, GEORGE W. HAWES. 



Analysis of the Andalusitic Slate, from the Portland 6^ Ogdensburg Railroad bridge 

 over IVilley brook. 



Silica, 46.01 



Alumina, 30.56 



Ferric oxyd, ........... 1.44 



Ferrous oxyd, 6.85 



Manganous oxyd, .10 



Magnesia, ........... 1.42 



Potash, . . • 6.66 



Soda, 1. 12 



Titanic acid, 1.93 



Water, 4.13 



100.22 



There are rocks on the east slope of Mt. Madison containing immense 



stauroHtes (described on page 1 14), which may possibly be the northward 



continuation of those occurring along the Mt, Washington carriage-road, 



amply illustrated upon Plate VII and page 116, There are also the Pine 



Hill rocks (p, 113), which are suggestive of the slate series. On the 



south it crops out between the Pinkham notch and Crystal falls. To 



the south in Jackson and west of the Ellis river is a large district that 



none of us have traversed, where this rock may be found, as along New 



and Cutler's rivers. A specimen collected for us by Prof. Vose, four miles 



above Jackson falls, is placed with these slates in our museum, and may 



possibly represent such an extension. The few ledges cropping out 



along Ellis river are referred to the Montalban series. 



An examination of the dips along the Mt, Washington carriage-road 

 VOL. II. 30 



