RECORDS 501 



the summit, while toward the periphery, nephehne appears as a 

 constituent, and a true foyaite is developed. The mass is also 

 cut by dikes, both camptonitic and syenitic. The region is to 

 form the subject of a petrographic study by the two geologists 

 in the near future. 



. Professor Martin described a visit which he paid during 

 the summer to the noted mineral locality at Haddam, Maine, and 

 the manner in which the choicest specimens occur there, in veins 

 of albitic pegmatite, with tourmaline, muscovite, and quartz along 

 the contact with the wall of gneiss. The mica plates along the 

 contact are often two feet in diameter. 



Dr. Julien briefly reviewed the observations and opinions 

 of Mitchell, Davis, Shaler, and others on the geology of Cape 

 Ann, with especial reference to the district from Chatham to 

 Yarmouth. In the stratified deposits of sands and gravels which 

 underlie the plain south of the morainal "backbone" of the 

 cape, the more frequent intercallation of clays was pointed out, 

 and their occasional disturbance and flexure. Striated pebbles, 

 although much water worn, are quite largely interspersed. The 

 discovery of true glacial silt at some depth, in one locality, in- 

 dicates that the ice sheet rested there, instead of floating. The 

 kettle- shaped hollows and pond basins were shown by the 

 speaker to be largely connected with the damming of surface 

 streams, and some observations on the pre-glacial drainage 

 valleys and topography were discussed. The identification 

 of certain transported fragments of quartz-porphyry with out- 

 crops of the same near Marblehead indicate a pre-glacial move- 

 ment from N.N.W. to S.S.E. To the fifteen changes of level 

 which have been recorded, a final small elevation probably should 

 be added, judging from the low terrace along this part of the 

 coast. Examples of the faceted pebbles were exhibited and pro- 

 voked considerable discussion among those present, as to the 

 origin of such pebbles. 



Professor Dodge recounted his pleasure in visiting the region 

 of the Grand Canon, in company with a party during the past 

 summer, and in finding the physiography so graphically illus- 

 trated in the drawings in Powell's reports to be a most faithful 



