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New York State Museum 



a mixture; it may be clay or of a calcareous nature or 

 a mixture of these substances with iron oxides The 

 conglomerates often receive their names from the charac- 

 ter of the matrix and we therefore have quartz-sand 

 conglomerates, calcareous conglomerates, argillaceous 

 (clayey) conglomerates and ferruginous (iron) conglom- 



ZT- u h u Ve arC " f6W ° ther ^ es of conglomerates 

 that might be mentioned. Sometimes, through the disin- 

 tegration of certain kinds of rocks as basalt among igne- 

 ous rocks, boulders of disintegration or residual boulders 

 are formed which with the sand formed through decom- 

 position forms a conglomerate rock which is known as a 

 residual boulder conglomerate. Arkose is a special kind 

 of sandstone (page 35) which often grades into con- 

 glomerates and breccias and these are arkose conglomer- 

 ates and breccias. Again pebbles of conglomerates may 

 be worn organic structures, as coral, shells etc. and we 

 then have coral conglomerates, shell conglomerates etc 

 Glacial conglomerates are produced from glacial deposits 

 such as moraines and outwash materials where the peb- 

 bles and boulders are commonly well worn. 



Conglomerates are quite common rocks, everywhere 

 distributed m sedimentary series. Thev are normally de- 

 posited by swiftly moving currents of water, such as 

 rapid rivers and estuarine currents, and are likewise 

 formed of the coarser material, gravel or shingle, thrown 

 by the waves toward the upper part of beaches. They 

 are, therefore, the first deposits laid down on new sea 

 bottoms when the sea is encroaching upon a sinking land 

 (page 44), since a beach formation necessarily sweeps 

 over the land at the front of the advancing sea as the 

 initial stage to later deposits. A conglomerate or coarse 

 sandstone is often the first or lowest member of a sedi- 



