XIII. QUARTZITE BOWLDER QUARRIES, DISTRICT OF 



COLUMBIA 



THE tribes of the Middle and Xortliern Atlantic States were 

 unfortunate in not having plentiful supplies of stone of good 

 quality for the manufacture of chipped implements. Had 

 such flints as those of the Ohio A\alley or the obsidians of California 

 been available, the deposits of quartzite bowlders and 

 MateHais^ o t e ^|^g coarsc-graiued rhyolites and argillites would cer- 

 tainly have remained unworked except perhaps for 

 making the heavy hammers, picks, and axes, for which purpose these 

 nuiterials are Avell suited. 



In the l^otomac and adjacent valleys water-worn stones are found 

 in vast numbei's where weathered out of the bluffs 

 Qimrik's '''"^^ and hillsides, and these were utilized for the manu- 

 facture of all classes of implements. So far as shown 

 by exploration, however, they were not extensively (luarried except 

 in what is now the District of Columbia, where deposits of cretaceous 

 bowlders, maiuly of quartzite and (juartz, outcrop along what was 

 once the shore line of the ancient cretaceous sea, and at points of 

 greatest utilization beneath heavy deposits of cretaceous (Potomac 

 formation) sands and gravels. On Piney Branch of Rock Creek, in 

 the northern section of Washington (fig. 43). the 

 posits °^ ^^ ^"^ local tribes must have found the bowlders of superior 

 quality for their purpose, for here they carried on 

 quarrying and blade-making operations of astonishing magnitude. 

 The bluffs and gentler slopes facing the creek and its tributaries in 

 the lower half mile of its course rise to the height of 100 feet or 

 more, but are nuich lowei- upstream. The Gneissic surface of the 

 ancient ocean bed and the Potomac strata which rest upon it 

 (fig. 44) slope gently toward the east, so that the bowlder deposits 

 which cap the terraced hills next Rock Creek pass beneath the level 

 of the branch east of Sixteenth Street.^ 



1 Tt is cause for lament that this beautiful valley, the resort for generntions of the 

 landscape painters of Washington, is fast being reduced (1910) by deep cutting and 

 filling to the monotonous condition of tlie ordinary suburb, and the charming rock- 

 bordered stream is becoming a deeply buried sewer. In the future it will bo known only 

 through incidental references in literature, as here made : and the interesting traces of 

 aboriginal occupation and enterprise will be forever obliterated. In 1892, when the 

 quarries were investigated by the writer, only two dwellings were located within the area 

 of the map (flg. 4:'.), there was but one bridge, and the stream itself had not been 

 molested in any way. 



38657°— 19— Bull. GO, pt i 12 159 



