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])art of .small and well-rounded pebbles, chieHv of different 

 varieties of felsite and <^ranite. It is a typifid puddingstone, 

 becoming a breccia only wiiere the basal conglomerate rests 

 directly upon the granite. lacing less intimately associated 

 with melaphyr than the Nantasket conglomerate, it is, as a 

 whole, less indm-ated, possessing less, })robably, of a distinctly 

 siliceous cement. This is es[)ecially noticeable, also, in the 

 arenaceous layers, which in Nantasket have the flinty hardness 

 of red quartzite, but in Ilingham are more like normal sand- 

 stone. The well-rounded and assorted pebbles are usually less 

 than an inch and i-arely more than two or three inches in 

 diameter. But at one locality, on the eastern shore of Huit's 

 Cove, the conglomerate is exceptionally coarse and irregular 

 in structure, containing rounded pebbles or bowlders of granite, 

 etc., of all sizes u]) to a yard in diameter. It is interesting to 

 note also that some of the pebbles at this point are an im[)ure 

 gray limestone, and that limited portions of the rock have a 

 distinctly calcareous cement. The finer portions of the con- 

 glomerate frequently become gradually but distinctly arenaceous ; 

 and most of the beds show repeated alternations of true 

 conglomerate with coarse, pebbly sandstone, so that it is quite 

 impossible to map the two rocks separately. Although the 

 conglomerate series is so largely arenaceous, there is compara- 

 tively little pure or t3qiical sandstone ; the most important 

 occurrence of this kind being the bed of gray or brownish gray 

 sandstone over a hundred feet thick in the Ilerscy Street 

 section. The sandstone is usually gray to light brown in color, 

 rarely distinctly ferruginous, and, as stated, rarely a good 

 quartzite. The brown color is probably due more to the 

 admixture of grains of red felsite than to a ferruginous cement. 

 The argillaceous rocks of Hinghain are quite varied. The 

 more limited I)eds of slate included in the conglomerate series are 

 usually of some shade of red, brown, or purple ; but the tiiicker 

 beds are in large j)art of a greenish or a gn^enish gray color, the 

 iron, evidently, being less highly oxidized. It is difficult, in the 



