GEOLOGY OF THE WHITE MOUNTAIN DISTRICT. 141 



locality in 1870, and brought back an abundance of notes and specimens, 

 which enabled me at that time to "refer the assemblage to this period. 

 Harvard brook is about three miles long, rising on the south-east side of 

 Mt. Kinsman in Bog pond. Less than a mile from its source a small 

 tributary enters from the north. Upon this and near the main stream 

 there is a vein of quartz three feet thick, dipping 80° E., imbedded in 

 the gneiss. Below the junction of the stream is the "Bog Eddy," an 

 extensive marsh. Between the bog and the upper fall occurred the fol- 

 lowing: Gray granite, with two kinds of mica; irregular, very coarse 

 granite, with masses of feldspar and quartz frequently eighteen inches 

 long; the ordinary gneiss with black mica, much jointed; coarse granite 

 eighteen inches wide, with the course N. N. E. ; similar rocks for ten 

 rods ; a coarse granite bed one foot wide dipping, like all above it, 60° 

 south-easterly; fine-grained granite eighteen inches wide, dipping sixty 

 to seventy degrees north-westerly, in which particular the rocks below 

 resemble it ; coarse granitic rocks for ten feet. The gneiss at the upper 

 Georgianna falls resembles somewhat the prevailing rock of Woodstock, 

 which has been referred to the porphyritic gneiss. The main falls are 

 situated upon the Franconia rock traversed by a two-feet dyke of coarse 

 granite. [See Fig. 41, Vol. I.] The banks of the stream between the 

 falls and its junction with the Pemigewasset have not been explored. 



It is probable that the Franconia breccia is a local deposit, though it 

 indicates a great disturbance among the more ancient formations. There 

 must have been a violent action to break up the older ledges into such 

 large pieces, and transport them to their present bed. If you believe 

 in the transformation of the original sediments by metamorphism into 

 the crystalline aggregates from which the pebbles were broken, it follows 

 that the porphyritic and perhaps other gneisses underwent their changes 

 prior to the Franconia period, since the fragments have experienced no 

 modification in mineral character after leaving their original situation. 

 It is hoped that some traces of this period will be found elsewhere in the 

 state before our explorations are finally brought to a close. Perhaps it 

 is represented upon Cascade brook above Beecher's falls. 



