PHOTOGRAPHING AND COLLECTING. 



J. Edmund Woodman. 



Thibe are few regions in wliich such opportunities are offered for 

 collecting representative specimens in variety, and for photograph- 

 ing forms, as in the vicinity of Boston. We are especially rich in 

 petrographic material illustrating rare rocks or structural varieties 

 and development, interesting to the petrographer more than to the 

 general geologist. It is impossible without undue expansion of 

 space to enumerate these opportunities, with the localities where 

 they are offered. The following list, however, made for the use of 

 one of the classes of the Summer School of Harvard University, 

 will give some idea of the richness of the region. The excursions 

 upon the basis of which this list was made are most of those in- 

 cluded in this guide. Objects unmarked can be both photographed 

 and collected ; those marked *can only be photographed. 



*Monadnocks ; veins ; *roches moutonnees ; *marine-benche8 ; 

 •eroded igneous sea-cliffs, with characteristic outlines ; flow struc- 

 ture in lavas ; aporhyolites ; *swinging sand-spits ; "partially sub- 

 merged and eroded drumlins ; *swamping in quiet areas ; marine 

 pebbles ; marine sand of different varieties ^ breccias ; weathered 

 diabase in all stages ; concentric weathering of diabase ; *talu8 

 cones of weathered material ; 'glacial striation ; *river gorge ; 

 •pot-holes ; 'glacial interference with drainage ; *cro8s-section 

 and outline of drumlins ; glacial till ; *dike chasms ; *till and sedi- 

 mentary rocks in process of erosion by waves ; "stacks ; "natural 

 bridges ; "complicated faulting and intersections of dikes ; igneous 

 rocks — granite, diabase, diorite, quartz porphyry, etc. ; "pocket 

 beaches ; "wall beaches ; algae protecting rocks ; barnacles pro- 

 tecting rocks ; "ripple-marks ; "rill-marks, often with deltas ; 

 "wave-marks ; "trails of organisms ; porphyritic structure ; "spout- 

 ing horn ; "cross- section of eskers ; esker gravel of various sizes ; 

 6 (66) 



